Production of work Production of work should begin with determining the dimensions of the fireplace foundation. First of all, you need to draw a plan of the fireplace at the level of the basement and combine it with the plan at the level of the firebox and chimney. The width of the foundation must match the width of the front

Production of reinforced concrete products The technological process for the production of precast concrete and reinforced concrete products consists of a number of independent operations, combined into separate processes. Operations are conventionally divided into main, auxiliary and transport operations.

General information and classification of asbestos-cement products The main raw materials for the production of asbestos-cement products are chrysotile asbestos and Portland cement. Depending on the type of products, as well as the quality of the asbestos used, its content in the products is

Materials for the production of asbestos-cement products Portland cement is used as a binder for the production of asbestos-cement products. It should hydrate quickly, but set relatively slowly. For the transition of a semi-finished product to a finished product

The main properties of asbestos-cement productsThe properties of asbestos-cement products are determined by the following factors: the quality of cement, the brand of asbestos, their quantitative ratio by weight, the degree of asbestos fluff, the location of asbestos fibers in the product, the degree

Production of metal products and structures In the manufacture of metal products, molten iron or steel is poured into special forms, the so-called molds, and then metal ingots from 500 kg to several (sometimes tens) tons are subjected to

Production and storage of seed mycelium In the early stages of the development of mushroom growing, wild mushrooms were used to grow mushrooms, but soon a number of disadvantages associated with this method were discovered. The most important was that the mycelium

3.6. Foundry Smelting is the transformation of solid metal, metal (cast iron) ingots and charge materials into liquid metal. Casting molds are filled with metal in liquid form, which, after solidification of the liquid metal, give it a certain

The technological scheme for the production of asbestos-cement products includes: reception, storage and supply of cement and asbestos to production; accumulation of process water, its recovery; preparation of a mixture, crumpling and fluffing of asbestos, preparation of asbestos-cement mass with its accumulation in an intermediate container; molding of sheet blanks (rolls) or pipes from asbestos-cement mass; cutting sheet blanks into formats and giving them a given shape; thermal and moisture treatment of asbestos-cement products during their hardening; mechanical processing of hardened products and quality control of products to supply raw materials to production - cement, asbestos of various brands, water. Then make a mixture of asbestos of various brands, knead and fluff, and then prepare a portion of the asbestos-cement mass from the asbestos mixture, cement and water and issue it into an intermediate container - a storage device for feeding the molding machines. The technological scheme for the preparation of asbestos-cement mass is given in Figure 4.19.

Fig 4.19.

• 1 - receiving hopper of asbestos; 2 - water dispenser; 3 - asbestos feeder;
• 4 - asbestos dispenser; 5 - runners; 6 - receiving hopper for runners; 7 - feeder of crumpled asbestos; 8 - batcher of crumpled asbestos; 9 - stirrer; 10 - disintegrator; 11 - turbo mixer; 12 - cement batcher; 13 - cement bin; 14 - dosing tank of water; 15 - collection of clarified water; 16 - recuperator

According to this scheme, asbestos is fed into the receiving hopper. 1 and further - into the hopper of the feeders 3. Asbestos is periodically dispensed from bunkers into dispensers 4 for weight composition of the mixture. The prepared portion of the mixture goes to 5 runners, where from the dispensers 2 water is supplied. Crumpled portion of asbestos through the receiving hopper 6 enters for intermediate storage in the hopper of one of the feeders 7. The feeder periodically delivers asbestos to the weighing batcher 8. A weighed portion of crushed asbestos and water in a predetermined amount are fed alternately into one of the mixers 9 for the preparation of an aqueous suspension of asbestos. From the mixers, a portion of the suspension passes through the disintegrator 10 into one of the turbo mixers 11, where from the bunker 13 with a dispenser 12 a weight portion of cement is fed, and from the tank 14 - portion of water. The asbestos-cement mass prepared in the turbomixer is periodically discharged into the bucket mixer (not shown in the diagram).

The schemes are applied without intermediate accumulation and storage of asbestos. Asbestos of different grades in a given weight quantity is poured into the receiving hopper of the mixer, mixed, and a portion of the mixture is fed to the runners for crimping, where water is supplied to moisten the asbestos.

The crumpled portion of asbestos is discharged from the runners into the mixer, and water is supplied there in the specified amount. A water suspension of asbestos prepared in a mixer is pumped into a gollender, where a weight portion of cement is fed from a batcher.

The prepared portion of the asbestos-cement mass is discharged into a bucket mixer for intermediate accumulation and continuous supply to sheet-forming machines.

Weight batcher CM-593 is used for weight dosage of asbestos. The dispenser (fig.4.20) has a frame 1 with a weighing mechanism installed on it, to which the hopper is suspended 2. Bunker straight

Rice. 4.20.

rectangular section, with a bottom in the form of a double-leaf gate 3, closed and opened by a mechanism 4. The shutter mechanism is controlled by a pneumatic cylinder 5 through a spool 9. Asbestos is fed into the hopper by a belt conveyor. The hopper itself with a shutter mechanism and a pneumatic cylinder is suspended from a system of levers 6.7, Jun 11 weighing mechanism. To ensure free movement of the hopper with the weighing system, air from the spool 9 fed into the pneumatic cylinder 5 on flexible hoses 8. Under the influence of the weight of the loaded asbestos, the hopper is lowered and through the system of levers and rods of the weighing mechanism acts on the pull 13 dial pointer 14 weighing device. Upon reaching the target weight, the thrust 13, when moving, switches off the limit switch 12, which stops the conveyor feeding the asbestos into the bunker.

The two-shaft mixer CM-923 is used to prepare a mixture of asbestos (Fig.4.21), has a trough 6 with two vane shafts 9 and 10, rotating in opposite directions. Shaft 9 driven by an electric motor 1 through the clutch 3 and reducer 2. From the gear 8, mounted on a shaft, rotation is transmitted through a gear 4 shaft 10.

Rice. 4.21.

Blades 11 are located at an angle to the axes of the shafts, which ensures the movement of asbestos along the mixer while mixing it. When changing the angle of the polo

As the blades move, the speed of asbestos passing through the mixer changes. Asbestos is fed into the hopper 5 and unloaded through the hatch 7.

Fluffing stages. The fluffing of asbestos is carried out in two stages. It is a cylinder with a conical bottom, in which a propeller fluffing device is installed. In addition, the hydraulic extinguisher is equipped with a pumping unit, with the help of which the asbestos suspension is repeatedly pumped through the pipeline and hitting the ribbed plates under pressure, which accelerates the fluffing of asbestos.

Asbestos is mixed with cement in a gollender or turbo mixer. The turbomixer is a cylindrical container with a conical bottom. It has a vertical propeller-mixing device. If the turbo mixer is installed above the bucket mixer, then the asbestos-cement mass enters it by gravity, if it is below the mixer, then with the help of a pump.

The bucket mixer serves to create a stock of asbestos-cement mass, which ensures uninterrupted power supply to the molding machines.

Bucket mixer СМА-82 (Fig. 4.25) is a metal body 5, in which a bucket wheel is located 9 and mixing device 8.

Rice. 4.25.

1 - drive; 2 - bearing; 3 - branch pipe; 4 - crosses; 5 - case;

B - blades; 7 - shaft; 8 - mixing device; 9 - bucket wheel; 10 - inspection hatch; 11 - bucket; 12 - receiving box; 13 - bracket;

The agitator body has the shape of a truncated cone, passing into a cylinder at a large diameter. Pipe branch 3 serves for feeding asbestos-cement mass into the mixer, hatch 14 - for descent, if necessary, of asbestos-cement mass. Receiving box 12 serves to supply the asbestos-cement mass to the forming machine. Mixing device 8 consists of three crosses 4 with

two rows of blades 6, arranged in a spiral. In the cylindrical part of the body there is a bucket wheel 9 with buckets 11.

In the production of asbestos-cement products by extrusion, it is necessary to prepare a plasticized asbestos-cement mass. Asbestos fluffing is carried out in two stages; the first is usually carried out in runners, the second in a disintegrator for dry fluff.

An aqueous solution of plasticizing additives (when using methylcellulose) is prepared in a reactor using hot and cold water.

Weighed portions of fluffed asbestos and cement are fed into a working mixer of dry components SLU-2000 (Fig. 4.26). The mixture is stirred in it for 4-5 minutes. To prevent the dry mixture from heating up, the mixer body is continuously cooled with water.

Rice. 4.26.

1 - rack; 2 - cover; 3 - plug; 4, 9 - hatches; 5 - case; 6 - stirrer; 7 - engine; 8 - reducer

The prepared portion of the dry asbestos-cement mixture is fed by the elevator to the mixer. In 2.5-3 minutes after the beginning of the supply of the dry asbestos-cement mixture, a portion of the solution of plasticizing additives is fed into the mixer.

Asbestos-cement products are made mainly by the wet molding process. Semi-dry and dry molding methods are used much less frequently. The latter is used in the manufacture of only flat sheets and tiles.

The wet method of technology begins with the preparation of a mixture of asbestos of several grades in order to ensure high filtration capacity, density and water retention during molding. After that, the asbestos fibers are fluffed up. Fluffed asbestos is thoroughly mixed with cement in water until a homogeneous mass is obtained. The latter is diluted with an additional amount of water, as a result of which an asbestos-cement suspension is obtained, into which, if required, additional substances (additives) can be added. In asbestos-cement slurry, the mass of water is more than 10 times the mass of cement. The finished suspension is sent to the molding of asbestos-cement products - sheets or pipes. In this case, most (over 96%) of free water is filtered and removed. The sheets are given the required size and shape. The cladding sheets and roof tiles are additionally pressed. The hardening of the binding part, under the influence of which asbestos-cement products acquire the required mechanical strength, occurs in warehouses or in autoclaves (with sandy Portland cement). Finished products can be given the required external surface by coloring and front processing.

To date, more or less definite compositions (mixtures) of asbestos of different deposits have been established in the production of asbestos-cement products. They are standardized by special technological maps.

The operation of asbestos fluffing largely determines the quality of the product. At the first stage of mechanical processing on runners, the bond between the finest asbestos fibers weakens within 12-15 minutes. At the second stage, in a gollender-pusher or other apparatus (6-8 minutes), asbestos is separated into the finest fibers. Generally, fluffing is preferred when wet, i.e. on runners in the presence of water. Gollender, that is, a metal tank inside which a drum equipped with knives rotates, is always a hydraulic pusher, since the separation of asbestos, crushed by the runners, into the finest fibers occurs in the pockets between the knives of the drum as a result of the action of rapid vortex movements of water jets. In the same apparatus, the mixing of fluffed asbestos with cement in an aqueous medium is usually carried out. Water is added simultaneously with cement loading from the bottom of the recuperator (waste water collector).

The asbestos-cement mass relatively quickly (in 8-10 minutes) acquires sufficient homogeneity, since the smallest grains of cement, carrying a high negative electric charge on the surface, quickly settle and firmly hold on the developed surface of fine-fiber asbestos, which also carries a high but positive charge in aqueous and alkaline environment. If sandy cement is used, then the smallest particles of dispersed sand also settle on the asbestos fibers, albeit with a longer mixing of the suspension (12-13 minutes). To obtain a mobile suspension requires 1 wt.h. dry asbestos-cement mixture add at least 4-5 wt.h. water, which is specified by calculation depending on the types of asbestos in the mixture.

The produced asbestos-cement mass is fed into a bucket mixer to obtain a certain mass reserve in order to maintain the continuous operation of the molding machine. From the mixer, the mass is directed along a chute into metal tanks, which are part of the sheet-forming machine. At the same time, recuperative water is continuously supplied to the chute, taken from the lower part of the recuperator, which allows maintaining the required consistency of the mass. The asbestos-cement slurry entering the baths of the mesh cylinders of the sheet-forming machine usually consists of 8-10% dry matter and 90-92% water. But there are other sheet-forming machines that use an asbestos-cement suspension of a higher concentration, for example, up to 40-45% dry matter (it contains up to 15% asbestos, up to 85% cement).

Wet molding of sheets and other asbestos-cement products is carried out on a cylindrical mesh molding machine (or semi-dry - on a filter belt). The principle of molding products consists in filtering water from layers of asbestos-cement mass under the influence of hydrostatic pressure until the required compaction (Fig. 9.30). For this purpose, a hollow frame-type cylinder 2 covered with a metal mesh (mesh drum) is located in a metal bath U filled with an asbestos-cement suspension. On the mesh, the mass is deposited in a thin layer and is partially dehydrated by filtering water through the mesh. The water from the drum is discharged first into thickeners (recuperators) to separate and return to production the non-settled part of asbestos, and then it is used for washing the mesh and cloth and liquefying

Rice. 9.30.

1 - bath; 2 - full drums with a mesh surface; 3 - asbestos-cement mass; 4 - pressure roller; 5 - endless cloth tape; 6 - vacuum box; 7 - format drum; 8 - support shaft; 9 - press shaft; 10 - washing device; 11 - squeezing rollers

asbestos-cement mass in the gutter. From the surface of the drum, a layer of asbestos-cement mass is removed with an endless cloth belt 5. Having passed the vacuum box on the belt b(with a vacuum of about 300 mm Hg), the previously dewatered asbestos-cement mass is transferred to a metal format drum 7, which removes the mass from the felt belt and winds it onto its surface in concentric layers, while it is compacted between rotating metal cylinders. When the asbestos-cement layer on the drum reaches the required thickness, it is cut along the generatrix of the cylinder, and the green sheet is removed. The pressure of the press section of the sheet-forming machine is usually 0.2-0.4 MPa, for the second bale roll 10.0-12.0 MPa, for the press roll - up to 40.0 MPa. As a result of compressions, the moisture content in the sheet is significantly reduced and reaches 25%.

In the manufacture of flat small products, the sheet is additionally cut into tiles, which are pressed in stacks under high pressure (up to 40 MPa) on a hydraulic press. If fibrous sheets are made, then undulating is carried out on special rolling-type machines of periodic action. There are continuous machines that are used in all automated lines.

Products harden in steaming chambers at a temperature of 50-60 ° C, a relative humidity of 90-95% for 10-14 hours, and then 5-7 days in an insulated warehouse. The hardening occurs faster in an autoclave under the action of steam with a pressure of 0.8 MPa, which allows the use of sandy cement and excludes the holding of products in the warehouse of the plant.

In the production of pipes, the principles of forming remain the same, but special pipe-forming machines with removable format drums (rolling pins) are used. The pipe and sheet forming machines do not have fundamental differences in the design of the baths of mesh cylinders, vacuum dewatering devices and devices for cleaning cloth.

At the end of the process of winding asbestos-cement layers, the format rolling pin is removed and a new one is installed. To make it easy to remove the rolling pin, the pipe diameter is slightly increased. For this purpose, the mesh at the ends is slightly stretched using metal wedges and the pipe is expanded on a special calender.

The dry method of forming asbestos-cement sheets involves fluffing up asbestos and mixing it with cement and sand in a dry form. For subsequent moistening, add 12-15% water, and compact the mass on a conveyor belt with rollers or under a press. Products, which mainly include floor tiles and tiles, harden in autoclaves. The dry method allows the use of short-fiber asbestos mainly of the 6th grade.

The textbook provides information on the properties of the main raw material for the production of asbestos cement - chrysotile asbestos and Portland cement.

The conditions of maximum use of the reinforcing properties of asbestos fibers in asbestos cement, the influence of the quality of Portland cement on the physical and mechanical parameters of asbestos-cement products are considered. Methods for calculating the optimal ratio of asbestos and cement in products are presented.

Technological methods of asbestos processing used by the industry and methods of forming various types of asbestos-cement sheet products and pipes are described. The physical-mechanical and chemical properties of products are given depending on the quality of the raw materials used and the method of their processing. The areas of application of the main types of asbestos-cement building products are indicated. The necessary technical and economic data are provided.

Tables 28, figures 90, bibliography - 60 titles.

Introduction

Asbestos cement, as the name itself indicates, consists of asbestos and cement, the weight ratio of which, depending on the type of product, ranges from 10/90 to 20/80.

Cement resists compressive loads well, but its tensile strength averages only 7-8% of the compressive strength. Therefore, in order to obtain a material with high compressive and tensile strength from cement, asbestos is introduced into it. Asbestos fibers, with a diameter of about 30 microns, uniformly penetrating the mass of cement, like metal reinforcement in reinforced concrete, increase the resistance of the material to tensile loads. The introduction of a small amount (10-20%) of asbestos into cement completely changes the physical and mechanical properties of cement stone: resistance to tensile and shock loads increases sharply, thermal conductivity drops significantly. It is punctured with nails and is easy to handle.

Freshly formed sheets of asbestos cement can be given a complex shape (wavy, semi-wavy, or other), which sharply increases their resistance to bending loads. All this makes asbestos cement a valuable building material from which lightweight, strong, fireproof and durable structures can be created.

The asbestos-cement industry is one of the most rapidly developing sectors of the national economy of the USSR. This is facilitated by the presence in our country of powerful deposits of chrysotile-asbestos, the reserves of which significantly exceed the deposits of Canada, the main supplier of this material to the capitalist countries. In addition to the main source of chrysotile asbestos - the world's largest Bazhenovskoye - since 1965 two powerful deposits have been put into operation - Dzhetygarinskoye and Ak-Dovurakskoye, and by 1970 two more powerful deposits - Kiembaevskoye and Molodezhnoye - will be commissioned.

Directives of the XXIII Congress of the CPSU are planned to increase the production of asbestos-cement products in 1966-1970. almost doubled.

During this period, the range of asbestos-cement products will also change significantly. If until now the bulk of products were roofing sheets for covering residential and public buildings, then by the end of the five-year period the output of structural asbestos-cement products, large-size flat facing sheets, asbestos-cement pipes for gas and oil pipelines, pipes for casing boreholes, large-sized profiled sheets for roofs and walls.

The workers of the asbestos-cement industry will be able to fulfill this huge program only through the rapid introduction of the latest high-performance equipment, maximum automation and mechanization of production. To do this, you need to know well the asbestos-cement production and skillfully use new equipment.

This textbook serves this purpose. In the seven years that have passed since its third edition, the theoretical understanding of the processes occurring in the asbestos-cement system has deepened, new machines have been created, which are successfully used in industry. These are devices for fluffing asbestos, for obtaining a homogeneous aqueous asbestos-cement mass and molding products. Automated technological lines are being introduced. The author tried to reflect all these changes in the fourth edition of this tutorial.

Since students of technical schools of the building materials industry take special courses on the equipment of asbestos-cement plants, on safety, maintenance and methods of monitoring technological processes, these issues are not considered in the textbook; the designs of the machines and apparatus used are also not considered; those schemes, which are given in the book, contribute to the understanding and better assimilation of the described technological processes.

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://www.allbest.ru/

Plan

Introduction

1. Technological process for the production of asbestos-cement products

1.1 Characteristics of the resulting product

1.2 Characteristics of the raw materials used

1.3 Characteristics of the technology for the production of asbestos-cement products

2. The structure of the technological process for the production of asbestos-cement products

2.1 Block diagram of the technological process for the production of asbestos-cement products

2.2 Operational structure of the technological process for the production of asbestos-cement products

2.3 Structure of the operation of asbestos-cement products

2.4 Technological transition structure

3. Dynamics of labor costs

4. The level of technology of the technological process for the production of asbestos-cement products

5. System of technological processes for the production of asbestos-cement products

Conclusion

Bibliography

Introduction

The asbestos-cement industry is a branch of the building materials industry that produces products that are used in the construction of buildings and pipelines for various purposes.

The first deposit of asbestos ores in Russia was discovered on the Tagil River in 1720 by the peasant Safran Sogra. At the same time, the manual mining of asbestos and the manufacture of asbestos fabrics began. The emergence of the asbestos industry dates back to the end of the 19th century, when in 1885 80 km. from Sverdlovsk, one of the world's largest asbestos deposits was discovered, which began to be named after the name of the nearest village of Baisenovskoye.

The first commercial Portland cement plant in Russia was built in 1856 in the town of Gradziec.

The presence of asbestos and cement served as a prerequisite for the emergence of asbestos-cement production.

The first industrial production of asbestos-cement products dates back to 1900. The inventor of the production method for these products is the Czech Ludwig Hashchek.

In the 20s of the 20th century in Italy, and then in other countries, the production of asbestos-cement pipes began to develop rapidly.

The asbestos-cement industry has become one of the leading industries in the production of building materials. In 1984, about 9 billion conv. Tiles of asbestos-cement sheet products and 76 thousand km. conv. pipes.

1. Manufacturing process

1.1 Haracharacteristics of the received products

The asbestos-cement industry produces sheet products - corrugated and flat sheets, including colored ones; pipes and couplings; electrical insulating boards; cement slabs; ventilation ducts.

Corrugated sheets are produced of the following types: VO - ordinary profile; VU - reinforced profile; UV - unified profile; SV - medium profile; CE - Central European profile.

VO sheets have a six-wave profile. Sheet dimensions 1200x686 mm, thickness 5.5 mm, wave pitch 115 mm, wave height 28 mm. The weight of one sheet is 9.8 kg. These sheets are used to cover residential and civil roofs; parts (ridge) for them are intended for laying at the intersection of roof slopes.

Sheets of the reinforced profile VU are intended for installation without attic roofs (VU-K) and wall fences (VU-S) of industrial buildings and structures. Roofing sheets are produced in lengths of 1750, 2000, 2300 and 2800 mm, wall sheets are 2500 mm long.

For housing and civil construction, sheets of a unified profile of hydrocarbons with a thickness of 6 mm are produced, and for industrial and agricultural - 7.5 mm. UV-sheets: used for attic roofs, residential and public buildings, as well as for the installation of insulated coatings of industrial premises.

Sheets of medium profile CB are made with a length of 1750-2500 mm. Sheets 1750 and 2000 mm. are intended for roofing of residential and civil buildings, as well as for roofing of buildings for agricultural production purposes, 2500 mm - for the installation of selenium fences of industrial buildings.

Sheets of the CE Central European profile have a wave pitch of 177 mm and a wave height of 51 mm. The length of the sheets is 1750, 2000, 2500 mm. They are used both as roofing and wall materials.

Flat pressed and unpressed sheets are produced in sizes from 700 x 900 to 3600 x 1500 mm. Pressed sheets have higher bulk density and mechanical strength. This ensures the reduction of water absorption and warpage of the sheets, which is very important when using sheets as facing. Flat unpressed sheets 1200x800 mm in size are used in non-critical structures and for cladding balcony railings. They are used for interior and exterior cladding of premises, the manufacture of sanitary cabins.

Pressure pipes are released at a pressure of 6, 9, 12 and 15 kgf / cm 2 with a diameter of 100 to 500 mm. Pipes up to 1000 mm in diameter are manufactured on request. The length of the pipes is 3, 4, 5 and 6 m. Asbestos-cement pressure pipes are used for pressure water pipelines at various pressures. It is known to use asbestos-cement pipes for transporting gas, various liquids and for chimneys.

Non-pressure pipes are produced with a diameter of 100-400 mm and a length of 3-4 m. The pipes must withstand a pressure test of 4 kgf / cm 2. Free-flow pipes are used for laying gravity sewer collectors, in agriculture for land reclamation and for cable ducts, especially when laying telephone cables.

Various types of couplings are used to connect pipes: Sshinlex, Zhibo and self-sealing asbestos-cement coupling (CAM), etc.

The main properties of asbestos-cement sheet products are assessed by a set of indicators such as density, statistical and impact strength, frost resistance, temperature and humidity deformations and warpage, as well as bearing capacity. The properties of asbestos-cement pipes are characterized by tensile strength, crushing and bending strength, water and gas tightness, as well as corrosion resistance when exposed to aggressive media found in a number of soils.

Hardened asbestos cement consists of several components, differing in density: cement clinker grains, hydrated from the surface; cement stone; asbestos fibers; particles of asbestos-containing rock in the form of hali dust. The density of asbestos cement will depend on the density and relative content of these components. In addition to the hydration of cement, an increase in the mass of asbestos cement over time causes the carbonization of lime in the hardening cement stone due to the addition of carbon dioxide and air.

The density of asbestos cement depends on the amount of porosity. The porosity of asbestos cement is 35-40% for unpressed sheet products, and 25-30% for pressed ones. The presence of porosity explains the ability of asbestos cement to absorb a significant amount of moisture, which is characterized by the amount of water absorption.

The static strength of asbestos-cement products is estimated by the ultimate strength in bending (R outg) in kgf / cm 2. VO corrugated sheets have a tensile strength of at least 160 kgf / cm 2, UV and SV-40 - 160-190 kgf / cm 2, flat sheets - 180-230 kgf / cm 2, ACEID boards - 350-500 kgf / cm 2.

The resistance of the pipe to internal pressure on the wall from liquid and gas is characterized by its ultimate strength at rupture (R break). Pipes designed to work under pressure must have a breaking strength of at least 225 kgf / cm 2, free-flow pipes - 160-180 kgf / cm 2.

Bearing capacity - the amount of load that an asbestos-cement product must withstand without permission.

Impact strength (or impact strength) is an indicator that characterizes the brittleness of a material and is estimated by the amount of work that needs to be spent on breaking the material. For asbestos cement, this indicator ranges from 1.5-2 to 4-5 kgf / cm 2.

Frost resistance is the ability of a material saturated with water to withstand alternating freezing and thawing without destruction and loss of strength. As studies by I.I.Berney, G.S. Blokh and others have shown, the strength of asbestos cement after freezing decreases on average by 10% at an average density of 1.57 g / cm 3 after 25 cycles, 1.65 g / cm 3 - after 50 cycles, 1.8 g / cm 3 - after 100 cycles.

The amount of warpage decreases with an increase in the density, thickness of the product, and an increase in the content of asbestos in it. The absolute values ​​of the deflection boom, depending on the indicated factors, range from 0.125 to 0.52 mm. Moisture deformations, in which the hardened asbestos cement swells when moistened and shrinks when dried, decrease significantly with an increase in the density of asbestos cement.

Water and gas tightness characterizes the ability of a material to pass gas and water through itself under pressure. Since asbestos-cement pressure pipes are designed to transport water and gas, they must be sufficiently water and gas tight. Both indicators largely depend on the density of the pipe, asbestos-cement pipes with a bulk density of 1.7-1.8 g / cm 3 are practically waterproof even at significant pressures (9-15 kgf / cm 2).

Gas has a higher ability than water to penetrate through small pores. Therefore, gas-piped asbestos-cement pipes must have a higher density than water pipes.

Resistance of asbestos cement in aggressive environments. Gases and liquids that are supersonic in relation to asbestos and cement stone are also corrosive to asbestos cement. Acids are dangerous for asbestos cement, including the acidic medium formed in the pores when the material is exposed to gases containing SO 3, supersive media are less dangerous for high density asbestos cement.

1.2 Harcharacteristics of the raw materials used

For the production of asbestos-cement products, Portland cement asbestos is used as the main raw material. The asbestos content in products depends on the type of product being produced, as well as the quality (grade) of the asbestos used. Usually, by weight, it is not less than 10 and more than 20%. The content of Portland cement in products is 80-90%, respectively.

Asbestos is the name for varieties of fibrous minerals belonging to the serpentinite and amphibole mineralogical groups. These minerals, consisting of filamentary crystalline aggregates, are capable of breaking down into very thin fibers, in cross-section down to molecular sizes.

According to the technical composition, asbestos minerals are hydrous silicates of magnesium, iron and sodium. The industrial value of asbestos minerals is determined, first of all, by their fibrous structure, as well as by such properties of asbestos fibers such as elasticity, high tensile strength, the ability to split into thinnest fibers under mechanical action, withstand high temperatures without significant changes in physical properties, and chemical resistance. For a number of industries, the high adsorption activity of dissolved asbestos, their good wettability with water and the ability to form homogeneous asbestos-water suspensions in the expanded state are of great importance.

All naturally occurring types of asbestos can be divided into two groups: non-acid-resistant and acid-resistant.

The group of non-acid-resistant asbestos includes one type - chrysotile asbestos. There are five types of acid-resistant asbestos: procidalite, amosite, anthophyllite- antinolite- and tremolite-asbestos ..

Chrysotile asbestos is of the greatest industrial importance. Its share in the world asbestos production is about 96%.

Chrysotile asbestos is located in serpentinite parods in the form of veins, and asbestos fibers are located perpendicular to the walls of the serpentinite rock. The highest quality asbestos - cross-fibrous asbestos - is extracted from such veins. In the course of mountain educational tectonic processes, some of the veins were compressed and the fibers in them were located at a slight angle to the walls of the enclosing rock. Longitudinal fibrous chrysotile asbestos is mined from such veins, the fibers of which are weaker, more rigid, and harder to crack.

Asbestos processing factories supply seven grades of asbestos, of which only four grades are used in the asbestos-cement industry: 3, 4, 5 and 6 ..

Portland cement for the production of asbestos-cement products is made by joint grinding of standardized clinker and the required amount of gypsum. The clinker is obtained as a result of firing before sintering the raw mixture of the proper composition, ensuring the predominance of highly basic calcium silicates in it. In the composition of cement, no more than 3% of additives that improve the properties of cement are allowed, and when grinding cement, with the consent of the consumer, it is allowed to introduce special additives as no more than 0.5% by weight of cement, which do not worsen its quality, but facilitate the process of grinding clinker ...

Portland cement for the production of asbestos-cement products is produced in two grades: 400 and 500. The grade of cement is established by determining the ultimate strength in bending of 4x4x16 cm beams and by compressing their halves made of plastic cement mortar of 1: 3 composition with normal sand and tested through 28 days (Table 1).

Table 1. Strength properties of cements.

The clinker used to make these cements must be of high quality. It is allowed to contain CaO free no more than 1% by mass, MgO - no more than 6% by mass, sulfuric anhydride - 1.5 ... 3.5% by mass. The amount of C 3 S in the clinker should be at least 51% by weight, and C 3 A - within 3 ... 8% by weight. An undesirable high content of alkalis Na 2 O and K 2 O, as well as ferrous iron FeO ..

Sandy Portland cement is also used, which is obtained by grinding Portland cement clinker together with quartz sand in a ball mill, and the sand content in such cement is in the range of 35-45% ..

1 .3 Characteristics of production technologyof asbestos-cement products

Consider the technology for the production of asbestos cement by the wet method.

The enterprises of the asbestos-cement industry produce two main types of products: sheet products and pipes. In the production of sheet products, asbestos supplied by conveyors is dosed according to brands by batchers (by weight) and delivered to the runners by a collecting conveyor. On the runners, and then in the hydraulic extinguisher, the first technological operation is carried out - the splitting (fluffing) of asbestos. To facilitate fluffing, a small amount of water is fed to the runners through a dispenser. Water is poured into a hydraulic extinguisher, where asbestos is processed in the form of a water-asbestos mixture (suspension) containing 50 g of asbestos per liter. water.

The asbestos slurry with fluffed asbestos is pumped from the hydraulic dryer to the turbo mixer, where cement is fed from the feed hopper through the batcher. After mixing the asbestos slurry with cement, the resulting asbestos-cement slurry is fed from the turbo mixer to the bucket mixer. Preparation of asbestos-cement slurry is the second technological production step.

From the bucket mixer, the asbestos-cement slurry is fed into a chute, where water flows through the pipeline to dilute the slurry. A diluted suspension containing about 100 g of asbestos cement in 1 liter along the chute. water flows into the baths of the sheet-forming machine.

Filtration of asbestos-cement slurry is carried out on three-mesh cylinders of the machine. Filtered water enters the sump, and from there it is pumped to the cooper. Wet layer of asbestos cement with a thickness of about 1 mm. by a conveyor felt it is fed to the sizing drum. Moving with the branch between the sizing drum and the press rolls, the layer is compacted, dewatered and transferred from the felt to the surface of the sizing drum. Filtration of asbestos-cement slurry, vacuum dewatering and compaction of filtered asbestos-cement on a forming machine are the most important technological operations on which the productivity of the machine and product quality depend.

After 5-7 layers of asbestos cement are wound onto the surface of the format drum and a roll corresponding to a given sheet thickness is formed, the roll is cut by a mechanical cutter along the drum generatrix and removed onto a conveyor. The latter feeds the reel to the mechanism, where the edges are cut off and the reel is cut to the sheets of the required sizes. Trims of raw sheets are fed by a conveyor to the mixer, where they are mixed with water, turning into an asbestos-cement suspension, which is returned to the bucket mixer.

After the cutting mechanism, flat sheets are stacked with metal spacers and sent to presses for additional compaction. If the plant produces corrugated sheets, then after the cutting mechanism, flat, freshly formed sheets go to the corrugating unit to give them a wavy shape. The sheets are removed from the corrugating unit by the stacker and stacked in small stacks on the conveyor of the heat treatment chamber, where the temperature is maintained at about 60 ° C.

After heat treatment, stacks of sheets on pallets are sent to a warm warehouse for ripening. After 5-7 days. from the moment of manufacture, the sheets are sent to the consumer.

Dosing and processing of raw materials in the production of asbestos-cement pipes is carried out in the same way as in the production of sheets. Pipes are formed on pipe-forming machines operating on the same principle as sheet-forming machines. The difference is that instead of the formatting drum, the pipe-forming machines are equipped with removable rolling pins, the diameter of which corresponds to the inner diameter of the formatted pipes. The pipes removed from the rolling pins undergo preliminary hardening on conveyors, and during the movement of the conveyor, the pipes rotate around their own axis and, as a result, acquire a strictly cylindrical shape. Curing of the pipes continues in water-filled basins or on water-hardened conveyors and then in stacks in a warm warehouse.

The production of pipes ends with cutting and turning of their ends after 7-10 days. after molding.

Asbestos treatment in runners. Runners have two cast-iron rollers with a diameter of 1400 mm., A width of 400 mm., Weighing 2800 kg., The axes of which are connected with a vertical shaft rotating at a speed of 12-16 rpm. To mix asbestos in the bowl of the runners, scrapers are installed on their vertical shaft. The height of the scrapers and the angle of their inclination to the direction of travel can be adjusted. Only the splitting of needles is a useful operation in the processing of asbestos in runners, and other “side” effects: the formation of non-chewed bundles, “breaking” of chewed fibers, the formation of fine fractions - deteriorate the quality of asbestos and the more so, the longer the treatment. Therefore, the duration of asbestos treatment in runners should be the minimum necessary.

Fluffing in water-dryers. The second stage of wet asbestos fluffing is carried out in hydraulic extinguishers. The hydraulic extinguisher has a cylindrical tank with a volume of 4.1 m 3 (working volume 3.6 m 3), in which a vertical mixer with a propeller with a diameter of 500 mm is installed, rotating at a speed of 480 rpm. The propeller is enclosed in a cylindrical diffuser. The mixer is driven by a V-belt transmission from a 40 kW electric motor. Suspension from the tank is supplied to the pump through a pipeline.

In order to periodically receive portions of the suspension with a volume of 3.2-3.8 m 3 and continuously supply the molding machine with the suspension, a bucket mixer is installed between the machine and the mixer, which is both a suspension accumulator and a feeder that feeds the suspension into the baths of the machine.

The turbomixer is designed to mix asbestos slurry with cement and obtain a homogeneous asbestos-cement slurry. The design of the turbomixer is similar to that of the hydraulic extinguisher. The difference lies in the absence of a fluffing unit. The turbomixer is a cylindrical container with a conical bottom. It has a vertical propeller-mixing device. The asbestos slurry enters a turbo mixer, where cement is then fed through a funnel. A portion of cement for one batch is 800-900 kg. As the cement is loaded into the turbo mixer, an additional amount of water is supplied to the full working volume. The duration of mixing with a pump of asbestos suspension with cement from the beginning of cement loading is 8-10 minutes.

The recuperator is designed to separate the maximum amount of solid particles from the waste water stream. This occurs as a result of a change in the direction of the water and a sharp decrease in the flow rate. The water, divided into two streams, one of which (cleaner) is intended for washing felts and nets, and the second, for thinning the asbestos-cement slurry, is returned to production.

The recuperator is a welded cylindrical tank with a conical bottom. In the center of the recuperator, a tapered pipe is fixed on screeds, gradually expanding from below. The upper part of the recuperator has an annular groove. The top of the recuperator body is closed with removable safety grilles. The conical bottom of the recuperator ends with a branch pipe to which a tee with a straight-through valve and a butterfly valve is attached. Another straight-through valve is installed at the bottom of the cylindrical part. The speed of water movement up the cylindrical part of the recuperator should not exceed 3 mm / s. At this rate, cement particles and asbestos fibers settle. Technical characteristics of the SM-922 recuperator: Capacity - 54.8 m 3; dimensions of the cylindrical part: diameter - 3850 mm, height - 3500 mm .; weight - 7555 kg.

In the asbestos-cement industry, CM-943 sheet-forming machines are used for the production of CB and CM-942 sheets, modernized HC sheets. Lines CM-1155 are equipped with machines CM-943A, lines for the production of HC sheets - machines CM-942A.

The unified cylinder mold is the main unit of technological lines producing asbestos-cement sheet products. The machine has two modifications, allowing it to be used in the production of sheet products of various types. The first modification of the SM-942A machine is wide, designed for the production of corrugated VO sheets, as well as flat ones. It is a three-cylinder machine that produces reel with a usable width of up to 1640 mm. (after trimming the edges). The second modification of the SM-943A machine is narrow, designed for the production of corrugated sheets of the UV and SV type. It differs from the wide, smaller width of the format drum, felt, tubs and mesh cylinders, pipe rollers, etc. and allows you to get reel with a useful width of up to 1340 mm.

Three mesh cylinders are installed on the SM-942A and CM-943A sheet-forming machines, which increases the layer thickness on the sizing drum and thereby increases the productivity of the place-forming machines.

The asbestos slurry enters the baths through openings in the end walls. Filtered from the mesh cylinders, asbestos-cement films are squeezed out by couch rolls and sequentially removed from the surface of the cylinders with felt, overlapping one another. As a result, an endless asbestos-cement tape with a thickness of 0.6-1.1 mm is formed.

Transferred to the top of the felt, the tape is dewatered by passing over the high vacuum box. Then it is compacted on a format drum with two additional press rolls and a main press roll. Then the cloth is directed to the accelerating roller, and the asbestos-cement tape begins to wind onto the format drum, forming a roll. Upon reaching the required thickness, the roll is removed from the drum with a cutter. The cloth is straightened with a spreader roller, cleaned with a swatter beater and washed from both sides from sclinker tubes, after which it is dehydrated, passing over a low vacuum box.

The format drum consists of two end discs and a cast iron shell, fixed to the discs by means of pins. One of the two discs is connected to the axle by a key. The sizing drum axis is mounted on two radial spherical bearings. The bearing housings are fixed to the bed.

The press shaft is a cast-iron tubular shell, pressed in the middle part onto the shaft, which has a cylindrical shape in a small area in the middle and tapers towards the ends.

The mesh cylinder is placed in the tub. The body of the bath consists of a welded body and cast tanks. The bottom of the bath has a slide profile with two depressions on the sides. In these depressions, on either side of the slide, there are two three-blade stirrers. Their purpose is to prevent the mass from settling on the bottom of the bath. At the same time, they should not wash off the layer of asbestos-cement mass deposited on the mesh cylinder.

Rice. 1.1. Scheme of the baths of the mesh cylinder.

1 - mesh cylinder. 2 - paddle mixers. 3 - screening tubes. 4 - cut-off rubberized rollers. 5 - vacuum box. 6 - press shaft. 7 - format drum.

Rice. 1.2. Diagram of a sheet forming machine.

1 - mesh cylinder. 2 - bath. 3 - technical cloth

2. The structure of the technological process of productionof asbestos-cement products

2.1 Block-process flow diagram

Posted on http://www.allbest.ru/

Posted on http://www.allbest.ru/

Block diagram of the technological process for the production of asbestos-cement products.

1 - splitting (fluffing) of asbestos into thin fibers;

2 - preparation of asbestos-cement mixture;

3 - molding of products;

4 - hardening of molded products in steaming chambers, water basins, autoclaves and keeping them in insulated warehouses until the desired strength is obtained.

2.2 The operational structure of the technologicalthe production process of asbestos-cement products.

Posted on http://www.allbest.ru/

Posted on http://www.allbest.ru/

Operational structure of the technological process for the production of asbestos-cement products.

Subject links -

Temporary connections -

2.3 The structure of theeration of asbestos-cement products

Posted on http://www.allbest.ru/

Posted on http://www.allbest.ru/

The structure of the operation of asbestos-cement products.

Subject links -

Temporary connections -

2.4 The structure of the technological transition of asbestos-cementproducts

Posted on http://www.allbest.ru/

Posted on http://www.allbest.ru/

The structure of the technological transition of asbestos-cement products.

Subject links -

Temporary connections -

3. Dynamics of labor costs

For a given technological process of production of asbestos-cement products, T l (t) = 2500 / (57t 2 +5700), and T p (t) = 0.003t 2 +0.3. Let's build a table and calculate the values ​​of T w, T p, T c at t equal to from 0 to 10.

Here is a graphical representation of the dynamics of labor costs in coordinates T-t.

Let us establish the point in time until which development is expedient. Graphically, this will be the point, the value of t, at which T cov (t) will take the smallest value. We denote this point by t c. The graph shows that 4

T "cov (t) = T" n (t) + T "w (t) = 0;

T "w (t) = (- 28500t) / (57t 2 +5700) 2; T" p (t) = 0.006t;

T "ow (t) = (-28500t) / (57t 2 +5700) 2 + 0.006t = 0;

Hence, t = 0 or 0.006 = 285000 / (57t 2 +5700) 2;

Let a = (57t 2 +5700);

Zn. 0.006a 2 = 285000;

(57t 2 +5700) = 6892.02;

Thus, we got that t c = 4.573.

Let us now determine the type of return on the additional costs of past labor.

To do this, we first express t in terms of T n.

T p (t) = 0.003t 2 +0.3; t 2 = (T p -0.3) / 0.003;

Let's substitute.

T w (T p) = 2500 / (57 (T p -0.3) / 0.003 + 5700) = 25 / 190T p;

Find T "W (T p)

T "w (T p) = (- 4750) / 36100T 2 p = (- 95) / 722 T 2 p;

Since as T n increases, the modulus T "x (T n) decreases, we can conclude that the type of recoil is decreasing.

Thus, until the moment of time t c = 6.137, rationalistic development is advisable, at which there will be a decrease in T sov. However, at t> 4 × 537, a further decrease in T ov will be possible only with the implementation of the heuristic variant of development.

4. Process technology levelproductionof asbestos-cement products

Consider T and T p for time t = 3 years.

T w (t) = 2500 / (573 2 +5700) = 0.402;

T p (t) = 0.0033 2 + 0.3 = 0.327;

Let's calculate the parameters of the technological process: the productivity of living labor (L), technological equipment (B), the level of technology (Y).

L = 1 / T w = 1 / 0.402 = 2.49;

B = T p / T w = 0.327 / 0.402 = 0.813;

Y = 1 / T w * 1 / T p = 2.49 * 3.06 = 7.62;

In order to determine whether the rationalistic development of a given technology is advisable, we calculate the relative level of technology (Y *) and compare it with the productivity of living labor (L).

Y * = Y / L = 1 / T p = 3.0581039;

Since Y *> L, then rationalistic development is expedient.

5. Technological process systemproductionof asbestos-cement products

There are two types of technological links in the system of technological processes: sequential and parallel. In accordance with the type of connections, some systems of technological processes allow the exchange of experience between the elements and are aimed at the development of the constituent elements, while others are aimed at increasing the output of products.

Let's graphically represent the structure of the building complex.

- sequential system

- parallel system

1 - Technology for the production of ceramic bricks by plastic method.

2 - Technology for the production of sheet glass.

3 - Technology for the production of Portland cement by dry method.

4 - Lime production technology / lump /.

5 - Silicate brick production technology.

6 - Technology for the production of asbestos-cement products.

7 - Technology for the production of precast concrete and reinforced concrete products.

8 - Technology for the construction of monolithic foundations.

9 - Technology for erecting brick walls.

10 - Technology of production of assembly works from prefabricated reinforced concrete structures.

Let's calculate for each structural element L (productivity of living labor), B (technological equipment), Y (technology level) for a period of 3 years. To do this, we need values ​​and for each structural element (Table 4.).

Table 4. Values ​​and for each structural element

Let's start by calculating L, B, Y.

L = 1 / (RUB (production) / RUB (human labor costs))

1.35; =1,42; =1,52; =1,52 =1,18;

2,49; =1,32; =1,43; =1,29; =2,24;

B = / (RUB (costs of past labor) / RUB (costs of living labor))

0,57; =0,697; =0,85; =0,95;

0,51; =0,81; =0,204; =0,23; =0,18; =0,63;

3,21; =2,898; =2,71; =2,41;

2,70; =7,61; =8,57; =8,77; =8,896; =8;

Let's calculate the volumetric labor costs:

= + N, where N is the ordinal number of the system.

11,04; =12,09; =13,14; =14,19;

15,24; =16,29; =17,34; =18,39; =19,44; =20,48;

Determine the volumetric indicators Q, F.

14,904; = 17,17; =19,97; =21,57;

17,98; =40,56; =22,89; =26,29; =25,08; =45,88;

35,44; =35,04; = 35,61; =34,19;

41,15; =123,97; =148,6; =161,28; =172,94; =163,84;

6,29; =8,43; =11,17; =13,48;

7,77; =13,19; =3,54; =4,23; =3,49; =12,9;

Let's define the total funds in the system:

Let's define the total output in the system. In a real system, the total output is determined by the limiting link:

14,904+217,17+321,57+217,98=149,914;

Let's define the real volumetric level of the system technology:

Let's find the technology level of the system:

Comparing the level of technology of the system with the level of technology for the production of asbestos-cement products and conclude that the element inhibits the development of the system (since<).

Let's calculate the system level of the technology in the optimal mode, i.e. when there are no limiting links. For this, we use the principle of “rolling up the system”, i.e. trying to find a level when there are no limiting links:

2(1/35,04+1/35,61)=70,17;

2(1/34,19+1/41,15+1/123,97)=129,039;

2(1/148,6+1/161,28+1/172,94+1/163,84)=640;

70,17+129,039+640=839,209;

Because there is a limiting link in the system, the system is not optimal.

Let's define the system output in the optimal mode:

Comparing the obtained result with the value of the total output in the system (= 149.914), we come to the conclusion that after optimization, the output decreased slightly. Let's calculate by how many% the production output in the system has decreased after its optimization:

Production output in the system decreased by 0.01% after its optimization.

For clarity, all the data obtained will be summarized in a table.

Calculation results

Conclusion

asbestos-cement product technology production

Experts believe that with the wet method of asbestos fluffing, the length of the fiber is preserved and the technological scheme of asbestos cement production is simplified. This method is less energy intensive in comparison with others, but it is associated with the consumption of large amounts of water. Also, the main advantage of the wet method of manufacturing asbestos-cement products using low-concentrated suspensions is that it provides high-quality asbestos-cement products.

As a disadvantage of the wet method for the production of asbestos-cement products, it should be noted the need to use at the initial stage of the technological process a large amount of water for fluffing asbestos, preparation of asbestos-cement mass.

Semi-dry method. A characteristic feature of the semi-dry method is that the molding of articles is not accompanied by the removal of excess water.

Extrusion method. The extrusion method can be used to manufacture products of complex configuration that cannot be obtained by other methods. This method can be used to manufacture products up to 3 m long and more, such as hollow slabs and panels for enclosing structures, suspended ceilings of buildings and structures.

Bibliography

Berney I.I., Kolbasov V.M. Technology of asbestos-cement products. M .: "High school". 1985.-p. 85.

Ioramashvili I. N. Asbestos-cement products. M .: "High school". 1977-from 50.

Meshkov GV, Volchek IZ “Production of asbestos-cement products”. M .: "High school". 1976-from 192.

Sivolobov IV Mechanical equipment for the production of asbestos-cement products. M .: "Mechanical engineering". 1983-s 200.

Sokolov P. N. “Production of asbestos-cement products”. M .: "High school". 1977-s 70.

Posted on Allbest.ru

Similar documents

The concept of asbestos-cement sheets, the properties of raw materials for their production. Specificity of technology, basic operations. Types of finished products, areas of their application. Technical and economic indicators. Analysis of the activities of JSC "Belgorodasbestcement".

term paper, added 11/02/2009


The use of glove products in the field of production or consumption, their classification features and consumer properties. Glove production technology and their technical and economic assessment, quality indicators, product standards.

test, added 03/05/2012


Description of the theoretical foundations of the technological process of manufacturing knitwear. Raw materials used in the production process. Information about the equipment used in the production of knitwear. Requirements for the quality of the finished product

term paper, added 04/23/2007


Characteristics of raw materials and finished products. The choice of packaging material for containers and packaging. Technology for the production of long pasta and instant pasta. Designing an enterprise for the production of pasta.

term paper added 09/11/2012


A review of the literature on the production technology of rubber products. Improving technology to reduce environmental stress. Material calculations of equipment, the specifics of measures for the safe conduct of the technological process.

thesis, added 08/16/2009


Substantiation of the method of production of bread products. Calculation of the acquisition of equipment for this technological process. Determination of the area of ​​production auxiliary premises. Water consumption. Sanitary measures in the production of bakery products.

term paper, added 12/22/2013


Basic materials for jewelry making. Precious, semi-precious and ornamental stones. Features of jewelry production. The essence of the polishing process. Washing jewelry. Embossing, engraving and enameling.

abstract, added 11/17/2011


General characteristics and purpose of gas silicate blocks, their classification and range. Raw materials for production, manufacturing technology. Basic properties, nomenclature, technical requirements. Drawing up a technological map of aerated concrete production.

term paper, added 04/13/2012


Activities and products of the plant for asbestos-vermiculite molded heat-insulating products. Scope and production technology of asbestos-vermiculite products, as well as quality control. Safety regulations when working with asbestos.

term paper added 09/29/2009


The current state of the bakery industry in Ryazan and the region. Characteristics of raw materials used for the production of bread "Darnitskiy", the technology of its production. Assessment of the quality of raw materials and finished products, their nutritional and energy value.