Screw press for coal. Coal briquetting technology. Testing of raw materials and binders for coal briquettes

Content

Affordable price compared to other types of energy resources, no problems with purchase, good heat transfer are the main reasons why many users prefer to use coal briquettes for heating. The price of more conventional energy sources is constantly increasing, which forces us to look for alternative heat sources. Coal dust is an accessible type of fuel, but its use in its pure form is unprofitable: half of the raw material falls into ash through the grate bars, and the other half is sintered, which leads to clogging of the firebox.

Coal briquettes

One of the options for using coal dust, which allows you to get maximum heat from it, is to pour the fraction on firewood, which is used to pre-heat the boiler. But this is very troublesome, since it needs to be poured often in small portions. Adding a large amount of fines will lead to the fact that it will still spill into the ash pan, turning into waste. And the part that still remains on the wood will fill the gaps between them, blocking the air circulation and causing the firebox to fade.

The solution is to produce briquettes from dust with the addition of auxiliary substances by pressing. The fine fraction processed in this way burns well with high heat transfer.

More about briquetting technology

At the beginning of the last century, Russian researcher A.P. Veshnyakov proposed pressing the fine fraction into elements of a certain shape and size, which in terms of heat transfer were not inferior to the coal itself. The idea has found wide application both in everyday life and in industry.

Coal briquettes on a screening belt

Today, pressed coal is classified depending on the material, environmental friendliness, security, shape and type of packaging. But the two main types are:

For production with the addition of binding components.
For home use without additives.

It is important to know that industrial briquettes should absolutely not be used in everyday life. When they burn, a large amount of toxic substances are released, for which special equipment is responsible for removing them under production conditions. Previously, additives in the form of molasses or starch were used in the production of household briquettes. But this technology is a thing of the past.

Industrial production

Distinctive features of dust and fine coal fraction: low specific calorie content and density. But these materials are considered as cheap raw materials that make it possible to organize the production of coal briquettes. The products will have good density and heat transfer at low cost.

To produce briquettes in a factory, a special production line is used, consisting of a crusher, dryer, and press. The movement of semi-finished products between machines is ensured by a conveyor belt.

Pressed coal without additives is produced in several stages:

Grinding raw materials to a particle size of 6 mm and smaller.
Drying the mixture to 15% humidity using steam and gas dryers.
Next, the dust is cooled and fed to a stamp-type press, which acts on the mixture under a pressure of 20-150 MPa (depending on what technology is used). After this processing, the finished briquettes are sent to the finished product warehouse for storage.

The purpose of the fuel and the equipment used are the main factors influencing the size of the particles, the level of humidity and the amount of pressure under which they are turned into briquettes. At the same time, the energy intensity of the finished product directly depends on the quality of the raw materials. It is important to use the fine fraction of anthracite, and not brown or other types of coal. For strength, it is permissible to add mineral or organic additives.

Coal briquetting press

Coal briquettes can be compressed in two ways depending on what briquetting equipment is used:

Stamp press. The heated coal mixture is filled into special molds, in which it is compressed with a force of 100-120 MPa. After cooling, the briquettes are packaged. The finished product looks like bricks or cylinders with holes, and may look like “tablets” or “pads.” This manufacturing method is suitable for the production of briquettes in large quantities due to the high energy and financial costs.
Extrusion machine. In this case, the plastic coal mass is pressed through the matrix by a press. A screw-pressed briquette (pini-key) made from coal dust has a cylindrical shape, resembling a “sausage”, with a calibrated hole in the middle. The technology is less expensive, but also less productive.

The technology for producing briquettes for industrial use involves the addition of cement, oil-bitumen mixture, liquid glass and others. The use of these substances in metallurgy is permitted. But you cannot buy coal briquettes with oil bitumen for heating a living space according to the requirements of the SES.

Briquetting coal at home

Industrial technology is not suitable for briquetting coal at home. The high price of equipment for the production of coal briquettes, high energy costs, and the need to obtain a huge number of permits from government agencies significantly increase the cost of the finished product. But for the purpose of heating a small private house, there is no need to organize large-scale production. To make 3-4 tons of briquettes (winter stock), it is quite possible to make do with improvised means.

Equipment for briquetting at home

The simplest method, which was well known to our great-grandfathers:

Coal dust is mixed with clay in a ratio of 10:1 with the addition of a small amount of water to form a thick mass. Clay is a safe binding component that will prevent the briquettes from falling apart. It is important to thoroughly mix all the components of the mixture. A construction mixer is often used for this purpose.
Next, the solution is poured into molds. These can be either special containers or used equipment (old pots, buckets, boxes). If there are no containers, coal cakes can be formed by hand, as our ancestors did.
After complete drying, the briquetted coal can be sent for storage.

Despite the fact that, according to production technology, the mixture is dried, during the home preparation of briquettes the mixture is moistened. In this case, homemade coal briquettes have the following distinctive features:

Imperfect shape.
Different levels of humidity and, therefore, heat transfer.
Low strength, which does not allow briquettes to be transported.

Homemade coal briquette

But these properties do not prevent low-cost products from burning well, especially compared to sintered dust. This option is much more convenient and practical.

And if you still want to automate the process somehow, then you can follow the example of home craftsmen and independently make equipment similar to production equipment:

A machine that allows you to make briquettes manually. Instructions on how to make a machine can be easily found on the Internet. A unit designed for home brick production is well suited for manual pressing. The materials that allow welding the frame are a profile pipe and a 40*40 mm corner. A receiving hopper is mounted on top. A manual mechanism is attached to the side for briquetting the mixture into rectangular or cylindrical products. Technology:
- The raw materials are crushed as much as possible. The fine fraction ensures the strength and quality of the briquette.
- Adding water will create a sticky mixture. It is acceptable to add clay in small quantities to slightly increase the ash content of the fuel.
- Next, the mixture is poured into a hopper, from where the mold is filled. The briquette is extruded by pressing a lever.
- The reverse movement of the lever causes the briquette to be pushed out of the mold. It is removed and placed in the sun to dry.
Screw press, where products are briquetted by extrusion. In this case, the financial costs of assembling the machine, as well as its productivity, will be greater. You will need:
- Thick-walled steel pipe for making the body. It is machined inside according to the desired screw size.
- Auger made from high-strength carbon steel.
- A matrix with one or more holes made of the same material.
- Electric motor with a power of 4 kW.
- Belt drive (minimum 3 belts).
- Reception bunker.

Technology for producing coal briquettes without a binder

It is better to entrust the manufacture of the body, matrix, and auger to a good turner. It is important that the pulley diameters ensure a screw rotation speed of no more than 200 rpm. The motor must be grounded before connecting it to the household electrical network.

Production technology:

The raw materials are crushed and mixed with water.
With the engine running, the mixture is loaded into the hopper.
The emerging “sausages” are cut into pieces of the desired length and laid out on a rack to dry.

It is important to know that the presence of through holes in finished briquettes promotes better combustion and greater heat transfer.

conclusions

If you believe the manufacturers of coal briquettes, the calorific value of this type of solid fuel is even greater than that of other varieties. Theoretically, this statement may be quite realistic due to the fact that only by burning 1 kg of anthracite can 7.7-8 kW be obtained. In terms of specific heat, firewood and wood briquettes lag significantly behind, releasing only 5 kW/kg.

However, an analysis of reviews from owners of solid fuel boilers on thematic forums shows that the demand for coal dust briquettes is lower than for wood for several reasons:

With their help, it is difficult to light a boiler and when burned, coal gives off little heat.
Before and during combustion, an unpleasant odor remains in the room.
Briquettes lose their shape and crumble heavily during transportation.
Lots of ash.

Combustion of coal fuel in briquettes

A large number of negative reviews (about 70% of the total) can be explained by the fact that manufacturers use low-quality raw materials in order to make more profit. They briquet charge, sludge and other types of coal that are unsuitable for heating premises, and add extra substances to the mass. Briquettes truly made from anthracite are difficult to find. The main feature is the deep black color of the products.

The conclusions are obvious:

It is better to make coal briquettes yourself.
For production it is necessary to buy high-quality raw materials.
If it is possible to purchase only low-calorie grades of coal, pressing is not economically feasible. Although burning low-quality briquettes along with firewood will reduce heating costs.

Yes, home-made coal briquettes are very different from their factory-made counterparts: they crumble during transportation, are wet, and produce less heat. But this way you can control the quality of the raw materials used, the presence and quantity of additives. Both in a boiler and a stove, “homemade” briquettes burn well, much better than dust, which is simply baked into a cake. In addition, in terms of price, homemade cylinders, bricks or “sausages” are much more profitable.

Approximately 25% of mined coal has a fine and pulverized fraction. This type of fuel is not in demand among consumers due to low thermal output. It is also inconvenient for heating private houses: it spills through the grate and therefore has low efficiency; often a large amount of fine or pulverized fuel blocks the access of oxygen, which causes the stove to die out. For these reasons, a lot of dust and coal of small fractions (up to 6 mm in size) accumulate in warehouses, in fuel sheds on private farmsteads. The problem is solved by producing briquetted coal. This technology makes it possible to produce fuel briquettes from coal dust at high pressure. What are the benefits of coal briquettes? They tolerate transportation and storage well, have a high calorific value compared to the starting materials (at least 6000 kcal/kg), do not emit smoke or gases, burn completely, without caking, but disintegrating into ash (the ash content of a high-quality coal briquette is no more than 10% depending on volume, but usually much less).

Coal briquetting technologies

Coal briquettes are made from brown coal, chips and dust of anthracite and hard coal, semi-coke and coke breeze. Depending on the type of feedstock, binders are added or not.

The formation of briquettes from brown coal occurs without the addition of binders, since the material itself contains up to 20% bitumen. During processing, the raw materials are crushed, heated and dried, bringing the humidity to 18-20%. After cooling, the resulting crumbs are fed into a high-pressure press, where lump fuel is formed. After cooling, they can be used or improved quality characteristics in semi-coking plants.

Briquetting of fine coals can also occur either with or without binders. During industrial production, the following substances are added as a binding element:

petroleum bitumen;
lignosulfonates;
molasses;
liquid glass;
cement.

Liquid glass and cement are used in the processing of certain types of coal and fine coke. Such briquettes are used in metallurgy in those processes where the presence of such components is acceptable. Coal tar and petroleum bitumen are also used to produce fuels for industrial applications. Such briquettes are not suitable for heating houses: during combustion, benzopyrene and other harmful substances are released, so they are prohibited by the SES and the demand for them is very limited.

For briquettes for household use, starches are most often used as a binding element, which are added to the crumbs until a viscous mass is obtained. Sometimes sugar, cellulose, and molasses are added. Clay, gypsum and lime are used less frequently, as they increase the ash content and reduce the specific heat capacity of the fuel. The type and quantity of the binding component is selected based on the qualities of the coal raw material during the production process. The mechanical characteristics of the briquette serve as a guide, but the energy value of the resulting fuel is also important.

The production of coal briquettes for household use consists of the following steps:

Drying. The less moisture in the raw material, the stronger the briquettes will be.
Removal of volatile components. This stage is necessary when processing low grade coal containing a large amount of volatile substances. A coke oven or distillation apparatus is used for this.
Grinding.
Adding binders and mixing it with coal chips. This composition is called the charge.
The mixture is fed to a press, where briquettes are formed under pressure.
In some cases (depending on the binder used), heating in an oven to 300 o C is required.
Cooling.

Developments in recent years have made it possible to form coal briquettes without the use of binders from any waste from the coal industry. Briquetting in such installations takes place in two stages. First, the crushed coal undergoes initial compaction by removing the voids between the particles. Then, by increasing the pressure to 100-200 Mn/m2, the particles themselves are deformed and compacted.

This releases phenols and resins, which, when water is added, form a natural binding component. The entire process is controlled by a microprocessor. The briquettes obtained in this way burn without smoke and do not emit harmful substances. Needless to say, such a coal briquetting press costs a lot? Hence the high cost of the final product. But coal of any brand is processed, the briquettes are strong, with a high calorific value, burn without smoke or any significant emissions into the atmosphere.

There are several other technologies that make it possible to make coal briquettes without binders. For this purpose, special roller presses are used, but not all brands are processed in this way. In some developments, some raw materials with a high tar content (caking coals) are added to the high-grade coal crumbs. The resulting mixture is heated to the plasticization temperature of sintered coals, after which the mixture is cooled slightly and then briquettes are formed.

Briquetting coal at home

Since the equipment for the production of coal briquettes cannot be called cheap, it is unprofitable to buy it for home use. But folk craftsmen found a way out of the situation here too. There is a way to make acceptable fuel from coal dust:

Take clay 5-10% by weight of the available coal raw materials, dilute it to a mushy state and mix with coal chips.
Place the composition tightly into the prepared forms.
Turn the formed briquette out onto plastic wrap and leave it to dry. After a few days they become strong enough to be stored in low stacks.

This type of fuel is suitable for heating a private home. But it is impossible to transport such briquettes - they crumble. They burn better than dust and produce more heat, but have a fairly high ash content - clay is added to the “own” ash.

There is also a mechanical method for briquetting fine coal and its dust. Using such a press you will not achieve industrial volumes and the resulting product will not survive transportation, but you can form fuel from the dust that is quite suitable for your furnace.

This is how these briquettes burn.

Agree, the installation looks quite workable, and if you have your hands, it’s not that difficult to do.

Charcoal briquetting

When producing charcoal, about a quarter of it turns out to be substandard - small pieces and dust. To turn this waste into income, you can make briquettes from them. Charcoal briquettes can also be made at home, if necessary, you can make raw materials for this (). The principle of briquetting charcoal is no different from the formation of the same fuel from coal:

Substandard coal is crushed.
Mix with binder. In this case, a regular starch paste will do the job well. The output should be a slightly moist mass. Some of the dust rolls into small lumps.
The resulting mixture is fed into a press, where briquettes are formed.

This video clearly shows the entire technology of charcoal briquetting, but the guys created a form specifically for the customer (church tablets made from charcoal for incense were ordered). Similarly, you can make a mold of any configuration.

conclusions. Briquettes from coal crumbs and dust (stone and wood) can be made at home. It is difficult to achieve commercial results (only through automation, and therefore expensive equipment), but for home use it is possible to make a simple installation.

Charcoal is a solid, porous, high-carbon product obtained from wood by heating without air (or with little air) in retorts, ovens or heaps. Many companies producing charcoal are faced with the problem of large waste of charcoal in the form of dust and small pieces (dropouts) due to the excessive fragility of the material.

Our company has found a REVOLUTIONARY solution to this problem and introduced to the market a NEW product - equipment for the production of charcoal briquettes in the form of an extruder-briquetting press with a thermoactive output die, PRODUCTIVITY from 500 to 1500 kg/hour!!! Special production technology allows us to achieve high quality and environmentally friendly finished products. Charcoal briquettes are produced by pressing a mixture of screenings, crushed into dust, with a binder on an extruder press, thanks to high pressure in the conical compression chamber (about 2000 kg/cm2) and heat treatment at the outlet. This allows us to produce high-quality briquettes of various shapes:
1. Round type “Nestro”, with a diameter from 40 to 60 mm - at the request of the customer.
2. Octagonal or square Pini-Key type “from 50X50 to 63X63 with a hole in the center.

Charcoal briquette (briquetted coal) is an environmentally friendly product that is used for grilling, barbecuing, etc., and it is also an ideal fuel for barbecues, stoves, fireplaces, all types of fireboxes, for heating tents, greenhouses. Charcoal briquettes are an indispensable tool for creating comfort while camping, on a picnic, fishing, or hunting.

The burning time of coal briquettes is 4-5 hours, unlike regular charcoal, which burns for 1-2 hours.

The constant temperature during combustion for 4-5 hours distinguishes briquettes from ordinary charcoal.

The ability to reuse charcoal briquettes - after use, they can be filled with water; under the influence of sunlight and wind, the briquettes dry out and are ready for use again.

Charcoal briquettes burn without smoke, do not spark, and during combustion practically do not emit any volatile substances, which eliminates the possibility of the spread of an unpleasant odor.

Sooner or later, every enterprise engaged in work related to the sale or processing of any type of coal is faced with the problem of accumulation of fine coal and dust. The dust fraction from 0 to 6 mm constitutes on average at least 25% of the total mass of incoming raw materials and, as a rule, entails difficulties in selling this volume or a significant reduction in the cost of its sale.

One of the most effective methods to solve this problem is to use the accumulated coal dust to produce coal briquettes. The production of fuel briquettes, despite all the attractiveness of this idea, does not have such a long history. Real interest in this issue has become acute and relevant only recently, due to a significant rise in fuel prices, including coal products.

Most attempts to organize the production of coal briquettes were frustrated either by the high cost of the technology or by the unsatisfactory quality and characteristics of the resulting briquettes associated with the use of cheap but poorly flammable binders, which repeatedly increased the ash content and minimized sales performance.
Our company offers an exclusive set of equipment that allows, using a fairly simple technology, to avoid the use of binders and other foreign impurities in the production of briquettes, with the exception of simple water.

This allows you to ultimately obtain a briquette in composition and characteristics that is in no way inferior to the original graded coal and avoids the usual disadvantages (foreign odor, high ash content, low calorie content, etc.) The main working unit of the proposed equipment is extruder presses, which are specially designed for briquetting rocks, anthracite pellets, coal slurries, brown coal crumbs, peat, etc. The pressing technology is based on adhesive-chemical processes occurring in visco-chemical systems formed by finely dispersed particles of fossil coals, which themselves act as binders. Simply put, during the operation of the press, such physical and chemical conditions are created that force the fossil organic components already included in the coal (phenols, resins, wax, etc.) with the participation of water to polarize on the surface of the particles, causing them to bind to each other. When cooled and dried, the briquette hardens and becomes fixed. Briquetted fuel has high thermal power properties, in particular sufficient mechanical strength, water resistance and heat resistance. When burned, the layer of such fuel has good gas permeability, which ensures a complete degree of combustion even with a relatively high ash content. To achieve maximum productivity of briquetting presses, our company has developed storage hoppers with screw pre-pressers, which ensure uninterrupted supply of the charge under the required pressure and at the designed speed. In addition, the briquetting line includes box conveyors with air coolers and a thermal grotto. To obtain the required moisture content of the mixture, mixing drums with a capacity of up to one ton of finished raw materials have been developed.
Due to the simplicity of the technological process, the equipment does not have complex technological components, does not require highly qualified maintenance personnel during operation and repair, and operates reliably in any conditions.

1. Briquetting line 16 tons per shift (shift 8 working hours). The following configuration:

Equipment	Productivity t/h	Number of units	Energy consumption kW/h
Hammer crusher	2-10	1	15
Forced mixer	2-3	1	3
Extruder press	2	1	18
Conveyor dryer (level 2)	2	1	20
Belt conveyor	2	3	1,5
Cooling conveyor	2	1	2,5

2. Briquetting line 40 tons per shift (shift 8 working hours). The following configuration:

Equipment	Productivity t/h	Number of units	Energy consumption kW/h
Hammer crusher	5	1	22
Forced mixer	5	1	3
Extruder press	5	1	40
Conveyor dryer (level 3)	5	1	30
Belt conveyor	5	3	3
Cooling conveyor	5	1	3

Ordinary sawdust and wood chips can be burned in boilers made for this purpose, but with coal dust it is not so simple.

Those who have already tried to heat their boiler with such fuel understood that half of it simply disappears, falling between the grate rods into the ash, while the second half is sintered into stone and prevents the burnt fuel from getting into the ash. All these reasons lead to a decrease in the quality of combustion, and therefore heat transfer.

But on the other hand, throwing away coal dust is, to say the least, stupid; it contains a large amount of energy. And here the problem can be solved by turning coal into briquettes, which we will talk about below.

More about briquetting technology

A number of parameters are used to classify fuel briquettes:

material from which the briquette is made;
form;
security;
environmental friendliness;
type of packaging.

You can, of course, burn such dust by first heating the boiler with wood, and then pour the fine fraction on it. But this approach is not a solution; it is very troublesome, because you need to add coal dust little by little, which means often.

If you immediately put a large amount of coal dust on the firewood, it will still spill into the grate and thus, the problem of partial combustion of fuel will not go away, besides, the rest of the dust will fall between the firewood, block the flow of air and the combustion will be significantly weakened.

To circumvent all of the above inconveniences, you need to press coal dust into briquettes, which in this form will burn perfectly, releasing all their energy.

Russian developments

The solution for pressing the fine fuel fraction was invented at the beginning of the last century by Russian researcher A.P. Veshnyakov.

His idea is still used in industry and everyday life. The essence of the idea is to press wood powder into solid elements that can burn and give off heat no worse than coal itself.

Without talking about detailed technology and without listing their types, it can be noted that they come in two main types:

using binding components, industrial combustion;
without them, for home use.

It is important to know: briquettes made using technology that involves the use of matching elements cannot be used in everyday life. When they burn, many toxic substances are released, which are removed by special equipment during production.

We are talking about the technology of producing briquettes without the use of binding components. Production proceeds as follows:

Initially, coal dust and small pebbles are crushed, the largest particle at the exit should not be larger than 6 mm;
Then the mixture is dried to a moisture content of 15%. For this purpose, steam and gas type dryers are used;
Then the dust is cooled and transferred to the press. Its effect on the fine fraction occurs with a pressure of 100 to 150 MPa, in a special stamp-type press;
after which the finished products are sent for storage.

Requirements for particle size and compaction pressure may vary depending on the equipment used and the purpose of the fuel. For example, the UNITEK production line works with particles up to 0.25 mm and their humidity from 6 to 16%.

As a result, we obtain a product with an ash content of 15-20%, capable of withstanding a pressure of -3 kg/cm, and when dropped from a two-meter height, the loss of weight from the impact will be insignificant. The energy intensity of briquettes will depend directly on the coal dust from which they are made.

Industrial production

For the production of industrial briquettes, the following binders are used:

oil bitumen mixture;
cement;
lignosulfonate additives;
liquid glass;
molasses.

To process small particles of coke and some other types of coal, cement and also liquid glass are often used. Such materials are used mainly in metallurgy, where the use of these substances is permitted.

Coal tar with petroleum bitumen is also used for the production of industrial coal briquettes. They cannot be used to heat residential buildings, as they release large amounts of benzopyrene and other toxic elements prohibited by the SES.

Home production

In order to make coal briquettes with your own hands, you need to have coal dust itself and clay, a safe binding element. By adding a little water, the dust and clay are mixed 10:1, so the solution acquires the desired consistency. It is very important to mix the substances thoroughly.

To create briquettes, you can use either a regular construction mixer or special equipment, such as the Weber brand. If you decide to make briquettes by hand, you can use any containers, boxes, pans, etc. as a form. At the end of production, the fuel briquettes must be dried.

Note: using equipment to create briquettes at home will be unprofitable.

Naturally, briquettes made at home are not ideal. Their strength is not as great as that of industrial analogues, they have different humidity and heat transfer.

But be that as it may, they burn perfectly in the boiler, much better than coal dust that bakes and falls through. And the cost will certainly please them. The positive reviews left about this technology speak for themselves.

How to produce coal briquettes, see the following video: