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.
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.
Requirements for environmental conditions at the installation site
| Installation height | up to 1000 m |
| Design for operation | indoors |
| Temperature | |
| On mechanical equipment | min. 5 °C |
| On control cabinets | min. 5 °C, max 40 °C |
| Air humidity | Max. 75% |
| Electrics | |
| Execution | DIN/IEC |
| Low voltage | |
| Nom. voltage | 400 V, ± 5% |
| Network frequency | 50 Hz, ± 5% |
| Control voltage | |
| Rated voltage | 24V DC current/110V |
| Network frequency | 50 Hz |
| Raw materials data: | |
| Feed material: | Coke breeze |
| Bulk density | 0.9 g/cm³ |
| Particle size Temperature |
up to 6 mm Environment |
| Max. permissible water content | 4% |
| Binder | Bentonite approx. 5% Starch approx. 2% |
Received product:
Description of equipment. Specifications
Frame
The press frame is a welded structure, manufactured in such a way that pressing forces are absorbed inside the frame and are not transferred to the foundation.
To facilitate the replacement of rolls, the end cheeks of the frame are connected to the upper/lower chords with hinge bolts. When the upper bolt is loosened, they (the cheeks) can be tilted to a horizontal position; they are used to remove the rolls.
Rolls
The rollers with axial journals are made of forged steel.
Press forms
Molds made of wear-resistant material are used, the molds are mounted on the roll body.
Setting the roll gap
The distance and clearance of the rollers is adjusted through intermediate parts inserted between the rolling bearing housing.
If desired, the gap can be controlled with an inductive displacement sensor by monitoring the parameters on the control panel.
Lubricated support
The rolls are mounted on ball bearings with bushings, the housings of which are sealed with labyrinth seals and rings. The bearings are filled with lubricant during installation.
Hydraulic pressing system
The roller is supported by the bearing housing on a hydraulic pressing device, which is necessary for uniform pressing force, as well as for uniform distribution of the load on the frame and protects the press from overload.
Includes:
- Pressure cylinder
- Nitrogen battery
- Pressure gauge
- Remote pressure sensor
- Safety valves
- Oil tank with pump
- Drive motor 3 kW
- Armature
- Fill level controller
- Thermometer
The hydraulic system maintains the set pressure and ensures constant pressing force.
Roll casing
To prevent dust, the rollers are surrounded by a casing, which is sealed in the rotating parts with labyrinth seals. The casing has a flange at the end for connection to the tray. Holes are provided for connection to the dust removal device.
Material supply
The gravity feed device is mounted on the press frame and consists of:
- Floor slab with loading funnel
- Hopper
main drive
The drive consists of:
- Gearbox with two outlet pins
- Safety coupling between motor and gearbox
- Two double gear couplings between the gearbox and the press roll
Instrumentation and A
Instrumentation devices are connected in terminal boxes (transfer point) with metric cable glands on terminal panels. The cable to the press is laid in flexible hoses. Cable designation according to DIN/IEC.
The following devices are installed on the press:
- proximity sensor with speed change relay on the main drive motor, 24V DC signal. current
- pressure sensor on the hydraulic pressing system for measuring oil pressure passive signal 4 - 20 mA
- Oil pressure solenoid valve
- Pressure gauge for monitoring hydraulic system pressure
On-site control panel (wall mounting)
To service the roller press during the production process, a control panel is installed next to the press.
The remote control is equipped with the following devices:
Painting- standard
Miscellaneous
1 set of tools for installing roller supports
1 set for checking and filling the hydraulic system
Material execution
All parts in contact with the product are made of structural steel unless otherwise specified.
The scope of supply includes the above equipment, except where specifically marked. Also included are drawings, necessary documentation for startup, operation, and a list of spare parts.
Optional
- Organization of the installation site, including cleaning and leveling, topographic studies, soil analysis, infrastructure organization
- Permits required by state and government authorities
- Construction and supply of buildings and internal construction of platforms for operation and maintenance
- Manufacturing and supply of mechanical connections to the Customer’s equipment in the installation
- Dust removal of pipelines
- Insulation and measures for its installation
- Consumables such as oils and lubricants
- Spare and wearing parts
- Transportation and storage of raw materials
- Materials, auxiliary devices (tools, cranes) and personnel for installation and commissioning
- Programming device
- Electrical equipment between low voltage distributors, control panels and electrical units, instrumentation, safety devices (fire protection, etc.)
- Departmental acceptance and start-up
- Transportation, storage and packaging of other finished products
- Other services and equipment not specified in the offer
Drying unit to ensure the required moisture content of raw materials before feeding it to the briquetting plant
While various wood wastes in the form of sawdust and wood chips are quite easy to burn in long-burning boilers specially adapted for this, the situation is different with fine coal and dust. Anyone who has ever tried to fire a stove or boiler with small fractions of coal knows that half of the fuel is wasted, spilling through the grate into the ash pan, and the other half is sintered and blocks the access of air to the firebox. Because of this, the intensity of combustion is sharply reduced. At the same time, it is stupid to throw away such fuel, because it contains a lot of thermal energy. In such a situation, coal briquetting can help, which will be discussed in this article.
About coal briquetting technology
One of the ways to burn coal fines is to light the boiler with wood, and then pour the dusty fraction of fuel on top of the burning logs. But this is too troublesome, since coal dust must be added in small portions, and therefore often.
If you load a large portion, then some of the fuel will definitely spill into the ash pan and go to waste, and the rest of the fuel will fill the cracks between the wood. Air will stop flowing into the combustion zone and, as a result, the firebox will begin to fade.
The best way is to use the pressing method to form briquettes from the fine fraction, which then burn very well, releasing a large amount of heat. Such a solution as coal briquetting was proposed at the beginning of the century before last in Russia by the inventor A.P. Veshnyakov is still successfully used both for industrial purposes and in everyday life. Its essence is that the compaction of fine coal using high pressure on special equipment makes it possible to obtain fuel whose calorific value is no less than that of high-quality coal.
Without going deeply into the intricacies of the technological process and the classification of different brands of fuel, we note that such briquettes are produced in two types:
- with binders for industrial purposes;
- without binders, intended for combustion in domestic boiler systems.
Note. Briquettes pressed with binders cannot be used in everyday life. When burned, these substances form harmful or toxic compounds, which are captured in industry in various ways. Previously, starches or molasses were also added to household fuel as binders, but this technology is outdated.
Since we are interested in the technology for producing coal briquettes without any additives for household purposes, it is worth considering this. So, the sequence of the process is as follows:
- first, the coal undergoes a grinding operation, with a maximum fraction size of 6 mm allowed;
- the next operation is drying in order to achieve an optimal humidity of 15%. For this purpose, special equipment is used for the production of coal briquettes - steam or gas dryers;
- After drying, the composition is cooled and supplied for pressing. The operation takes place at a pressure of 100-150 MPa in the so-called stamp press;
- final cooling and shipment to the warehouse.
Note. The traditional technological process is described here, but the requirements for the fraction size and moisture content of the raw materials may vary depending on the equipment used. For example, a modern mini-plant of the Russian company UNITEK requires particle sizes of up to 0.25 mm with a moisture content of 6 to 16%. That is, in this case, the coal briquetting technology should provide for better grinding, but the pressing pressure is applied much lower.
The output is a coal briquette whose ash content does not exceed 15-20%, the maximum permissible mechanical load is 3 kg/cm2, and when dropped from a height of up to 2 m, the product loses no more than 15% of its mass as a result of impact. The heat of combustion depends on the grades of coal from which the briquette is pressed.
Making coal briquettes at home
It is clear that industrial equipment for coal briquetting is inaccessible to the average homeowner due to its high cost. However, our grandfathers also knew how to make briquettes without any equipment. To do this, coal dust and crumbs were mixed with water in such a ratio that a thick mass was obtained, and then cakes were molded from it by hand. After drying, such products were successfully burned in a home stove. That is, contrary to production technology, the mixture for the production of coal briquettes is not dried, but, on the contrary, moistened.
At home, briquettes are made in 2 ways:
- using a hand press;
- on a homemade screw extruder.
The first method is good because you can buy a pressing machine inexpensively or make it yourself. Its disadvantage is low productivity; in order to make yourself a fuel briquette for the whole season, you will have to work very hard. In the second case, briquetting of coal dust occurs quite quickly, since the entire process is mechanized. But here the cost of the unit comes to the fore; even a homemade installation will require significant costs. You will need to purchase a powerful electric motor, gearbox and other parts.
The algorithm according to which you can make coal briquettes yourself is as follows:
- You must try to grind the coal chips in any available way. The smaller the fraction, the better the quality of the product;
- mix the resulting composition with water. It is not possible to indicate exact proportions, since they depend on the dust content. The main thing is that the mixture is very thick and molded by hand. There is no need to add clay, this will only increase the ash content;
- fill the mold with the composition and operate the manual mechanism;
- Remove the briquetted coal from the mold and leave to air dry.
As a result, we get fragile products that are unsuitable for transportation, but burn well in the stove. One of the ways to briquet coal at home can be found by watching the video:
When a screw press is available, production is greatly simplified and accelerated. Turning on the electric motor, the above mixture is loaded with a shovel into the receiving hopper of the extruder. The output is cylindrical “sausages” of excellent quality. It is worth noting that such briquettes made from coal dust have good strength and can even be transported.
For more information about the operation of the extruder, watch the video:
Conclusion
Of course, home-made briquettes are far from ideal. They have low density and high humidity, and therefore provide less heat than factory products. However, in a stove or boiler they burn well, it’s not like burning coal dust that bakes into a cake. And in terms of cost, homemade coal briquettes will be cheaper.
