Ceramic brick shop

Contents

Contents

Introduction

1 Process Part

1.1 Product nomenclature

1.2 Raw Materials

1.3 Selection and justification of production method and process diagram

1.4 Operating mode and working time fund

1.5 Production Program Calculation

1.6 Equipment calculation and selection

1.7 Calculation of warehouses and silos

1.8 Calculation of power demand

1.9 Calculation of manpower requirements

1.10 Product and Process Quality Control

2 Occupational and environmental protection

List of sources used

Summary

The course design includes an explanatory note consisting of 41 pages, including 2 drawings, 6 tables, 10 sources, Appendix A, and a graphic part of the format A1 on which the plan and sections of the molding mass preparation department are made.

In this course project, the main calculations required for the design of the plant were made, the nomenclature of products, raw materials were described, the state of development of this industry was highlighted, as well as the main provisions on safety and environmental friendliness of the project.

Introduction

One of the most common materials traditionally used in the construction of buildings and structures is brick. More than a thousand years of brick practice makes it possible to unambiguously classify it as the most durable building materials. The production of construction ceramics is an important branch of the national economy. In the overall balance of production and use of wall materials, ceramic bricks occupy more than 30%.

The ceramic facing brick market is a sub-market of the brick market as a whole. When acquiring it, the buyer is driven by other motives than when buying an ordinary brick - to give the object under construction a more aesthetic appearance, to get satisfaction from a beautifully built house.

At the moment, in the production of construction ceramic bricks, attention is focused on improving technology, improving the quality of products and expanding the range. During the construction of new enterprises, it is envisaged to establish automated and highly mechanized technological lines based on modern domestic and imported equipment.

The production of effective hollow products is being mastered, which should gradually replace the traditional full-bodied brick. This will not only save raw materials, but also reduce the thickness and mass of the outer walls without reducing their thermal protective properties, as well as create lightweight panel structures for industrializing construction.

The main raw materials for the production of construction ceramics are clays. Clays are called earthy debris rocks that can form plastic dough with water, which, after drying, retains its shape and, after firing, acquires the hardness of the stone. Clays were formed as a result of weathering of field-stepped rocks, and weathering is both physical and chemical in nature. During physical (mechanical) weathering, monolithic rocks are destroyed into individual blocks, pieces and particles as a result of water, temperature and wind . Water penetrates into rock cracks and destroys them due to proppant action and dissolution of rock components. Under the influence of temperature changes , rocks are deformed, leading to their cracking and destruction. The temperature effect is exacerbated by the presence of water, which at negative temperatures turns into ice that breaks rocks. The wind blows out and carries away particles of destroyed rocks, contributing to their further destruction.

Until recently, most bricks were produced by plastic molding. The disadvantages of this method include the fact that molded bricks need to be dried. And to obtain a high-quality brick surface, the drying process must be slow. As a result, drying takes from 3 days to several weeks, and, despite the fact that many factories introduce a whole range of additives into clay to reduce brick cracking during the drying process (such as chamotte, sawdust, coal, shale, etc.), it is still possible to ensure that the brick does not crack, not many. Today, every head of a plastic molding plant faces a choice. Or try to produce more or less high-quality bricks. And for this, it is necessary to increase the drying time of the brick and increase the amount of additives in the mixture. The first increases energy consumption by 1.52 times, the second also leads to an increase in the cost of finished bricks, since any additive costs much more than clay. Or produce cheaper, but low-quality bricks. A second disadvantage of the plastic molding method is that in order to obtain high-quality bricks, clay needs to be qualitatively processed, which requires high energy costs. Therefore, most domestic enterprises use a minimum set of processing equipment, which does not contribute to the quality of bricks produced. I especially want to say about the use of a fleet of drying and roasting cars. So, for a brick factory with a capacity of 10 million pieces of brick per year, about 100 roasting cars, 500800 drying cars and about 20,000 drying frames are required. Given that both cars operate in aggressive environments, their useful life is short, and as a result, the cost of repairing and renewing the fleet of cars occupies a significant place in the cost of brick. Another method of producing bricks is a semi-dry forming method. This method is widespread in the Rostov region and the Krasnodar Territory, where almost half of the large brick factories work using this technology. Semi-dry brick factories also operate in the Belgorod, Voronezh, Nizhny Novgorod, Moscow regions and the Urals. The semi-dry forming method involves drying clay in a drying drum for 1015 minutes, after which the clay is ground with a rod mixer into powder with a fraction of 0.55 mm and formed into brick with knee-lever presses. [4]

Since the moulding takes place at 810% powder humidity, the molded brick does not require drying and is fed immediately after moulding into the furnace. Therefore, no energy cost is required for drying, no addition to clay is required to improve the drying properties of brick, even if there are salts in clay, they do not protrude on the surface of brick, the technological equipment is simpler and consumes significantly less electricity. At the same time, the costs of building the plant are reduced, since: semi-dry pressing equipment costs several times cheaper, the size of the building is much smaller, there is no brick drying compartment, which usually occupies a rather large space. Comparative analyses of the work of brick factories show that the cost of brick ori in a semi-dry method is 2 times lower, which allows you to consistently earn high profits in modern conditions. With regard to new construction, I would like to note that the semi-dry molding plant occupies 2 times less area than a similar plastic molding plant, and its construction costs 22.5 times cheaper. At the same time, I would like to talk about furnaces with a removable vault that have been widely used in the Rostov Region. These furnaces combine the advantages of annular and tunnel furnaces. That is, on the one hand they are completely mechanized, on the other hand, they do not require a fleet of roasting cars. The brick is loaded into these furnaces and unloaded through the arches in packages of 300600 pieces. After loading, the roof is covered with plates of refractory material, and firing is carried out as in a conventional annular furnace. The advantages of this furnace include the dispersed extraction of flue gases, which makes it possible to obtain bricks of a guaranteed higher grade than in a tunnel furnace.

In the current conditions, it is possible to satisfy the demands of builders and architects on the production volumes, nomenclature and quality of ceramic bricks, focusing on the production of construction ceramic bricks on improving technology, improving the quality of products and expanding the range.

During the construction of new enterprises, it is necessary to establish automated and highly mechanized technological lines based on modern domestic and imported equipment. Develop the production of effective hollow products, which should gradually replace the traditional full-bodied brick. This will not only save raw materials, but also reduce the thickness and mass of the outer walls without reducing their thermal protective properties, as well as create lightweight structures of panels for the industrialization of construction. [3]

Process Part

1.1 Product nomenclature

The nomenclature of the designed plant was selected in accordance with the task: ceramic brick format 1NF void 25% with cylindrical voids - 60%; brick of solid format 1,3NF - 40%. Productivity - 50 million pieces of conditional brick per year.

Solid brick and hollow brick are manufactured in accordance with GOST 5302012.

The main technical requirements related to the brick to be produced include the following:

The brick shall be in the form of a rectangular parallelepiped with even faces on the faces. The surface of the bricks may be corrugated. Bricks with rounded corners with radius of rounding up to 15 mm are allowed

The voids in the brick must be perpendicular or parallel to the bed and can be through or through.

Width of through slot-like voids must be not more than 12 mm.

The thickness of the outer walls of the brick shall not be less than 12 mm.

Deviations from the specified dimensions and parameters of brick appearance shall not exceed the following values on one article:

Limit deviations from nominal dimensions in millimeters shall not exceed (for plastic molded articles)

Lime inclusions that cause destruction of surfaces and breakdowns with a depth of more than 6 mm after steaming are not allowed.

On the surface of the articles, it is allowed to have breakaways by the largest measurement from 3 to 6 mm with a number of not more than 3  pcs.

Specific effective activity of natural radionuclides (Aeff) in articles should not be more than 370 Bq/kg.

Each batch of delivered products shall be accompanied by a quality document indicating:

- name of the manufacturer and (or) its trademark;

- name and symbol of articles; 

- document number and date of issue ;

- batch number and quantity of items to be shipped; 

- mass of bricks and stones ;

- water absorption;

- brick and stone grade in terms of strength and frost resistance;

- specific effective activity of natural radionuclides;

- thermal conductivity of articles ;

- designation of this standard [2]

1.2 Raw Materials

The name of the clay rock is clay of the 4H subgroup. The recommended purpose of the rock is brick grade 100 or more with a weed. Content of particles with size less than 10 μm - 40-60%, less than 1 μm - 25-35%.

The chemical content,% by weight, shall be as follows:

- SiO2 - not more than 85, including free quartz not more than 60;

- Al2O3+TiO2 - not less than 7;

- CaO+MgO - not more than 20;

- sulphur compounds in terms of SO3 not more than 2, including sulphide not more than 0.8 (at SO3 not more than 0.5%, including sulfide not more than 0.3%, during tests of clay rock, methods of eliminating heights and fading on burnt products by converting soluble salts to insoluble ones should be determined);

- FeO+Fe2O3 not more than 14;

- K2O + Na2O is not more than 7.

The water absorption of the burnt tile (without signs of burnout), characterizing sintering, should be no more than 6%.

Content in clay rock of fine fraction less than 1 mcm should be more than 15%, fraction less than 10 mcm more than 30% by weight, content of fraction 0.010.5 mm is determined, but not regulated.

The content in the clay rock of coarse grains (particle size over 0.5 mm) of inclusions larger than 5 mm shall not exceed 5% by weight. [2]

Quartz sand is used as a sweetening additive. The amount of sand added as additive should be 10%. Sand shall be given a radiation and hygienic assessment. It shall not exceed Aeff≤ 370 Bq/kg. During acceptance inspection, the following is determined:

- grain composition;

- content of pulverized and clay particles;

- clay content in lumps. [3]

1.3 Selection and justification of production method and process diagram

The process of making articles by semi-dry pressing method includes the following groups of operations: quarrying, preparation of powder, pressing, drying and roasting of articles.

Quarrying in this case does not have any specifics and is carried out according to the mining conditions of the clay deposit.

Raw materials are subjected to coarse crushing on stone-separating crushers, where separation of foreign coarse inclusions takes place. Drying is carried out in drying drums arranged on the principle of direct flow, since with countercurrent there is a danger of strong overheating of clay, its partial dehydration and a large loss of plastic properties. The temperature of the gases entering the drum is usually 600800 ° C. The normal temperature of the exhaust gases should be 110120° C, a sharp increase in this temperature indicates overweight of the clay. The temperature of the clay discharged from the drying drum is 6080 ° C, the humidity is 911%. When clay passes through the drum, its particle size distribution changes. Small fractions, drying quickly, abrade to a pulverized state, and large pieces, sawing, stick together and roll into large comas. This causes a large humidity inhomogeneity of dried clay, which complicates the operation of grinding machines. Increased uniformity of drying is achieved by device of chain curtains, which partially grind clay. Then a large fraction (more than 6 mm) is separated through the mesh, which is returned to the drying drum for re-drying. During the preparation of the press powder, it is not always possible to obtain a powder with the moisture necessary and sufficient for pressing after grinding. Such humidification is carried out in a blade  mixer.

The beginning of the pressing of the ceramic powder is accompanied by its compaction due to the displacement of the particles relative to each other and their approach. This is the first stage of compaction. The air is partially removed from the system. The next stage of compaction is characterized by plastic irreversible deformation of particles. This increases the contact surface between the particles. At the same time, the compaction of each elementary particle is accompanied by the squeezing of moisture from its depth layers onto the contact surface of the particle. In the third stage of compaction, elastic deformation of particles occurs. Such deformations are most likely for thin elongated particles in the form of needles and plates, which can bend according to the scheme of a clamped cantilever or beam resting on two supports. The last stage of compaction is accompanied by brittle destruction of particles, in which the compaction receives the greatest compaction and the greatest adhesion due to strong further development of the contact surface. Brittle deformations require a very high pressure, which is practically not achieved by semi-dry pressing of most ceramic articles. 

Compacted raw material is dried in tunnel dryers on furnace cars. Drying time 1624 h. Final humidity 46%. Heat carriers are hot air drawn from the cooling zone of tunnel furnaces, as well as their exhaust gases. Heat carriers are hot air drawn from the cooling zone of tunnel furnaces, as well as their exhaust gases. Initial coolant temperature is 120150 ° С.

The semi-dry pressing firing process is as follows. The "massif" of raw material is formed by mechanical convergence of individual grains of ceramic powder, in which each grain has a structure similar to plastic dough, and in the raw material there remain interfaces between them, despite the apparent strong interaction between the grains of powder during its pressing. In the semi-dry pressing crude, the role of the colloidal fraction is significantly changed. It acts mainly not on the contact surfaces of the particles, but inside the particles themselves and aggregates the primary grains of minerals into the clay particle, rather than cementing the compressed particles with each other. With this arrangement of the colloidal fraction, the liquid phase during firing develops primarily not on the contact surfaces of clay aggregates, but inside them. A relatively small amount of liquid phase occurs on the contact surfaces of the clay aggregates. It does not provide continuous cementation of contact surfaces. Cementation is in this case a contact sintering character similar to "spot welding." This explains the reduced resistance of the semi-dry pressing articles to bending.

After firing, finished products go to the warehouse.

The advantages of the semi-dry pressing technique are that the pressed raw brick is laid directly on the furnace cars and dried on them in tunnel dryers, or, bypassing pre-drying, is directly fired. Complex mechanization of production is easier than with the method of plastic molding. However, semi-dry pressing technology requires a more advanced aspiration system in the preparation and transportation paths of powder, the use of more high-performance presses.

2 Occupational and environmental protection

Safety requirements for technological processes (types of works).

The following measures shall be provided during design, organization and implementation of technological processes to ensure safety:

- removal of direct contact of workers with raw materials, blanks, semi-finished products, components (units, elements), finished products and production wastes, which have dangerous and harmful effects;

- replacement of technological processes and operations associated with the occurrence of hazardous and harmful production factors, processes and operations in which these factors are absent or do not exceed the maximum permissible concentrations and levels;

- integrated mechanization, automation, application of remote control of technological processes and operations in the presence of hazardous and harmful production factors;

- hermetization of the equipment or creation of increased or reduced pressure in the equipment (fixed by the device) (compared to atmospheric);

- application of protection means for workers;

- development of safety control and control systems of the production process, including their automation of external and internal diagnostics on the basis of computers;

- application of measures aimed at preventing the occurrence of hazardous and harmful production factors in the event of an accident;

- application of waste-free technologies of the closed production cycle, and if this is not possible, then timely disposal, neutralization and disposal of wastes, which are the source of harmful production factors; the use of a recirculated water supply system;

- application of rational work and rest modes in order to prevent monotony, hypodynamics, excessive physical and neuropsychiatric overload;

- protection against possible negative impacts of natural nature and weather conditions. [8]

Bunkers. Hopper hatches shall have folding covers which are locked. On the side of loading by road transport, bunkers should have a baffle bar with a height of at least 600 mm. The hoppers shall be equipped with devices to prevent rake-up and hanging of materials (electric vibrators, steam-electric heaters, pneumatic pumps, agitators, etc.).

Before descending into the bunker, it is necessary to:

- exclude the possibility of loading the bunker by transport for the duration of the work, for which purpose set the traffic observer on the above-bunker platform, include traffic lights or light signals prohibiting loading;

- disconnect and brake loading and unloading devices;

- remove fuses from electrical switchboards of drives of loading and unloading devices and display the prohibition safety sign;

- provide the workers with the necessary boom cranes, winches, runners, flooring and personal protective equipment.

Before repair, the hopper shall be free of the material in it. [9]

Do not:

- is located on the bin grille during inspections and maintenance (removal of rubble, hangings, rakes, wedges of material, etc.);

- descend people into bunkers for elimination of arch-formations and hangings.

The poppet feeder shall be covered with metal shelters.

Before repairing the poppet feeders, the following conditions must be met: material is produced from the receiving bin; the possibility of its loading is excluded; gate valves on feeder receiving holes are closed; electric motors are disconnected from the power supply network; fuses from electrical switchgears are removed, and a prohibition safety sign with an explanatory inscription is posted on the launchers.

It is forbidden to remove protective fences, push and remove stuck pieces of material, metal, boards and other objects, clean silos, dispensers, feeders from stuck material during operation of dispensers and feeders.

Belt conveyors. Safety precautions shall be ensured by following:

- frames of inclined conveyors shall be equipped with platforms with railings along the entire conveyor line;

- to pass through the conveyor, every 2550 m transition bridges shall be provided with railings;

-A pull cable shall be placed along the entire conveyor line to enable the drive to be turned off from any point on the line;

-The conveyor control circuit shall be provided with interlock preventing the possibility of the drive re-actuation until the emergency situation is eliminated;

-the conveyor design shall provide easy safe access to components, units and control devices requiring periodic inspection, as well as control, loading and unloading devices, manholes controlled manually or mechanically;

- spontaneous movement in the reverse direction of the load-carrying element with the load is not allowed when the drive is disconnected in conveyors having inclined or vertical sections of the route;

- Conveyor load tensioners shall have end stops to limit the travel of the tension trolley and limit switches to turn off the conveyor drive when the tension trolley reaches the extreme positions;

- moving parts of conveyors (drive, tensioning and deflecting drums, tensioning devices, ropes and blocks of tensioning devices, belt and other transmissions, couplings, etc., as well as support rollers and rollers of the lower branch of the belt) shall be enclosed in areas of permanent process-related workplaces on the conveyor or along the entire conveyor track if there is free access or constant passage near the conveyor of non-conveyor-related persons;

-protective barriers shall be equipped with devices for their reliable holding in closed (working) position and, if necessary, be blocked with conveyor drive for its disconnection at removal (opening) of the barrier.

Drying drum. Control of start-up, operation and stop of dryers shall be centralized and brought to the board installed at the driver's workplace.

Dryers shall be automatically interlocked with their accessories and devices and shall be equipped with sound and light alarm.

Each drying drum shall be equipped with the following instrumentation:

- for measurement and accounting of fuel consumption and dried product output;

- to measure the temperature of the gases before entering the mixing chamber and the drum;

- to measure the temperature of the gases leaving the drum and behind the electrofilter, as well as the temperature of the dried material at the outlet of the drum;

- to measure the vacuum upstream of the drum, dust collecting device and smoke pump;

- to measure the air pressure supplied to the furnace by the blast fan;

- to measure the pressure of the fuel (liquid and gaseous) supplied to the furnace;

- for alarm about reaching the upper limit of temperature in the coal dust hopper, about reaching the upper and lower limits of heating temperature of fuel oil, about overheating of the most important bearings, about emptying and overflowing of hoppers of raw and dried materials, coal dust hopper or fuel oil tank; excess of gas temperature downstream the drum and downstream the electrofilter;

- unit operating time counters.

An electric clock shall be installed in the dryer room.

Monitoring of compliance with IPA (IPA)

Enterprises for which IPA (IPA) are installed shall organize a system for monitoring compliance with IPA (IPA), approved in accordance with the established procedure.

When monitoring compliance with IPA (IPA), the main methods should be direct methods using measurements of the concentration of harmful substances and volumes of gas-air mixture after gas treatment plants or at places of direct release of substances into the atmosphere.

Balance, process and other methods are used to improve the reliability of MPA (VES) control, as well as when direct methods cannot be applied (see reference annex 4).

When monitoring compliance with IPA (IPA), emissions of harmful substances are determined over a period of 20 minutes, to which the maximum single MPC belong, as well as on average per day, month and year.

If the duration of release of harmful substances into the atmosphere is less than 20 minutes, control is carried out on the complete release of harmful substances during this time.

Under adverse meteorological conditions, during short periods of pollution of the atmosphere dangerous to public health, enterprises must ensure a reduction in emissions of harmful substances, up to a partial or complete shutdown of the enterprise.

If the MPA (VES) is exceeded as a result of an accident, the enterprise must, in accordance with the established procedure, inform the authorities exercising state control over the protection of the atmosphere and take measures to reduce the emission of harmful substances into the atmosphere until the plant stops and eliminates the consequences of atmospheric pollution, as well as transmit information about the accident and measures taken.

Efficiency of step-by-step reduction of emissions of harmful substances is estimated by the degree of actual reduction of air pollution determined in accordance with regulatory documents approved in the established procedure. [10]