HU213316B - Method for producing water-proof briquette - Google Patents

Description

The present invention relates to a process for producing waterproof briquettes. The term "briquettes" means any physical form of fine-grained, easy-to-use fuel for domestic or industrial use. Examples include egg briquettes, briquettes, pellets.

The particulate fuel of the present invention can be any carbonaceous material such as lignite or coal powder, charcoal, coke, petroleum coke or a mixture of these products. These materials, especially crushed coal and coal dust, are produced in large quantities by modern mining and coal washing processes.

Among the applications of these materials are the briquettes.

Various methods of cutting granules or powders are known, which generally use additives or binders to ensure proper cohesion.

Among the additives and binders most frequently used are coal pitch, black pitch, petroleum pitch, bitumen, lignin sulphonates, clay, polysaccharides, in particular starches and starch derivatives.

The most commonly used binder is undoubtedly coal pitch, but due to increasingly stringent environmental requirements, its use is declining.

Its use requires the briquettes thus produced to be heat treated or smoked to reduce the concentration of phenolic compounds. However, this treatment does not involve minor atmospheric pollution. In addition, since the de-smoke is incomplete, the combustion of the briquette when used causes harmful gas formation to the person.

These inconveniences have led to a ban on use in some countries.

The disadvantages of using a pitch also occur when using bitumen as a binder.

To overcome the disadvantages, it has been proposed to use lignin sulfonates, especially ammonium, as binders.

The scientific literature on the use of these products is very abundant, for example, in the case of Soviet 983.147,1.010.146,1.137.103, European Patent No. 0,097,486, European Patent 3,227,395. German Patents Nos. 224,331, 4,666,522 and 4,666,522.

The lignin sulfonate cleavage process is complicated and requires very high skill to execute. On the one hand, it is necessary to dry the grits to the exact moisture content so that the lignin sulfonate grits mixture can be crushed, since excess water or lack of water makes the operation impossible. On the other hand, during the polymerization of lignin sulfonates and thus heat treatment to make the briquettes waterproof, a harmful sulfuric acid-rich flue gas is produced, which is one of the negligible causes of environmental pollution.

In order to solve this pollution problem, it has been proposed to equip the equipment in question with various equipment, including the condensation of flue gas. However, the use of such equipment has led to the pollution problem becoming a corrosion problem, which is known to be very difficult to overcome, especially when treating sulfuric acid-rich condensates, even if special steels are used for the milling equipment.

In any case, whatever the planned solutions, the disadvantages of using lignin sulfonates make the process expensive.

In addition, the briquettes produced by this process have the disadvantage that upon combustion they produce sulfur residues which are found in the smoke.

Methods have been proposed which do not show the aforementioned disadvantages of pitch, tar and lignin sulfonates, and in which these binders are replaced by clay, namely bentonite (U.S. Patent 4,025,596 and German Patent No. 1,671,365). However, the briquettes produced by these processes do not have all the required physical properties, in particular their strength is poor and their water resistance is medium. Therefore, these procedures are not widespread in practice.

The use of starch as a binder has also been found, which, when used alone or in combination with other binders, has several advantages, as disclosed, for example, in U.S. Patent No. 3,726,652, Federal Patent Specification 3,227,395 and European Patent No. 0,097,486.

A 1982 comparative study of pelleting at Berkeley University (K.V.S. Sastry and D.V. Fuerstenau) showed that starch had better results than asphalt emulsion or bentonite:

- mechanical pressure resistance,

- wear resistance,

- in the field of impact resistance.

In addition, starch can be used without limitation in industrial equipment originally designed for the most commonly used binders, pitches or bitumen, so its use does not involve any additional investment; and maintenance of equipment is cheaper.

Finally, the burning of starch-bound briquettes does not produce toxic and / or contaminating flue gas.

A major disadvantage, however, is that starch-based briquettes, like bentonite-based briquettes, are very sensitive to water, which makes it impossible to store them in the open air.

To overcome this disadvantage, it has been suggested that starch be combined with pitch, asphalt or bitumen or rendered insoluble with urea-formaldehyde, phenol-formaldehyde, melamine-formaldehyde, ketone-formaldehyde resins or a mixture thereof.

None of these solutions is entirely satisfactory, as each raises the problem of producing toxic and polluting flue gases when the briquettes are produced.

U.S. Patent No. 1,507,673 discloses a solution for making carbohydrate-based briquettes waterproof, adding a significant amount of a strong acid, particularly phosphoric acid, and treating it at a temperature of 200-540 ° C.

This solution is also unsatisfactory since, like lignin sulfonates, the treatment produces corrosive flue gas. In addition, treating the strong acid is a delicate operation.

It has also been suggested that the briquettes are coated with a water repellent film or film obtained using emulsified wax. Although this is an original but costly solution, the amount of wax used and the protection against moisture can change if the protective film is damaged due to impact during transportation.

Finally, European Patent 89 400071 discloses waterproof briquettes which contain a carbohydrate as a binder and an organic silicon containing water as a water repellent.

Such briquettes, although suitably weather resistant, have the disadvantage that their surface is relatively fragile when wet. It is known that during their treatment their appearance is damaged and a significant amount of dust is formed.

Consequently, none of the present processes can produce briquettes with satisfactory mechanical properties and water resistance under economically and environmentally acceptable conditions.

Therefore, it is an object of the present invention to overcome the disadvantages of the prior art and to produce briquettes which better meet the various practical requirements than those which already exist.

It has been found that this can be achieved by compressing the particulate fuel with an organic binder and an oxidizing agent and drying the resulting briquette.

Thus, the process for producing the waterproof briquette of the present invention comprises:

- use of fine-grained fuels, organic binders and oxidants,

- mixing the oxidant with either a fuel or an organic binder or both, or a mixture thereof,

- compressing the mixture thus obtained,

- drying the briquettes obtained by cutting.

In a preferred embodiment of the process according to the invention, the organic binder used is molasses, cellulose, hemicellulose, flour, protein, starch, derivatives or mixtures thereof, preferably starch and starch derivatives.

In another preferred embodiment, the oxidizing agent is a water-soluble oxidizing agent, such as hypochlorite, perborate, persulfate, percarbonate, bromate, peroxide or a mixture thereof, preferably persulfate, more preferably ammonium persulfate.

It is desirable to combine the action of the oxidizing agent with the action of appropriately selected metal ions which exhibit catalytic activity in the oxidation process. Examples include the ions of copper, zinc, iron and other divalent metals.

When the organic binder used in the process of the invention is a starch or a starch derivative, these terms include:

- starch of any origin, natural or hybrid, native starch, such as potatoes, manioc, maize, waxy maize, high amylose maize, wheat and milling products thereof, barley or sorghum;

- the term starch derivative means starches physically and / or chemically modified.

The organic binder is preferably native starch, which may be solubilized in cold water by drum-drying and / or gelatinizing treatment.

Relative to the weight of the fine-grained fuels in the process of the invention

0.2 to 25% by weight, preferably 1 to 15% by weight, more preferably 2 to 7% by weight of organic binder,

0.01 to 10% by weight, preferably 0.025 to 5% by weight, more preferably 0.05 to 3% by weight of the oxidizing agent is used.

In a preferred embodiment of the process according to the invention, the water-soluble oxidant can be added in powder form to the fine fuel and / or the organic binder and / or a mixture of the two.

In another preferred embodiment, the oxidant is added in the form of an aqueous solution to the fuel and / or to a mixture of fuel and organic binder.

The crushing technique used in the process of the present invention is selected from pelletizing, compression, extrusion and molding; these techniques are already known and are described, for example, in European Patent Application No. 0,017,486.

In the process according to the invention, the briquette obtained by the chopping treatment is dried, generally at a temperature of 150-500 ° C, preferably 170-300 ° C, more preferably 190-250 ° C.

In a preferred embodiment, at least one organic silicon-containing water-repellent agent is added to the fine particulate fuel, the organic binder, the oxidizing agent, or a mixture thereof to reduce the risk of re-uptake due to capillaryity of the fuel obtained by the process of the invention. exposure.

Preferably, the organic silicon-containing water repellent is a compound having the structural structure represented by formula (I). In the formulas, R and R 1, which may be the same or different, are organic radicals and, as the compound, preferably non-reactive silicone oil, silicone resin, reactive, namely hydroxylated, alkylated, arylated, hydroalkylated, hydroarylated silicone oil or mixtures thereof may be used.

A water-repellent agent can also be used for the silicone of formula II, wherein

- R? is alkyl, alkenyl or aryl,

X is an alkali metal or alkaline earth metal atom and

- 1 <n <10, and most preferably potassium silicone.

In this preferred embodiment of the process according to the invention, the mixture of materials used in this particular application forms a new industrial product, as well as the briquettes thus obtained.

In another embodiment of the invention, the briquette may also contain other ingredients such as carbonates, unleavened or slaked lime, dolomite, alkaline silicates, clay, latex, borax, polyphosphates, phosphates, concentrated milk and / or lactose, cement, vinyl alcohol) and thermosetting resins. The proportion of such ingredients may be up to 15% by weight relative to the weight of the fine particulate material; their particle size should preferably be close to that of the fine particle.

The present invention will be further illustrated by the following examples of preferred embodiments.

/. example

Charcoal based briquettes (Control product)

Weigh into a mixing machine 50 kg of charcoal with a grain size of less than 1 mm and 3 kg of native wheat starch. This mixture was heated to 50 ° C at this time

4.5 L of water is added. The resulting mixture was stirred for half an hour while raising the temperature to 90 ° C; the final humidity measured with a device known as CENCO is then 8.5%. The mixture is compressed by compaction on a SAHUT CONREUR press; of the process characteristics, the temperature of the blend at the time of cutting is approx. 70 ° C, the control pressure is 16.7 x 10 ⁵ N / m (1 Pa = 1 Nm ^-2 ; ΙΝ / m = 1 Newton / meter, where IN = 1 kgxm / s ² , so 1 N / m = 1 kg / s ² ); the speed of the press rolls is 5 rpm and the power of the press is 6 kW.

Thus, we obtain a briquette which, raw, has sufficient cohesion to withstand transport.

The strength of the briquettes, measured with a counter pressure gauge supplied by SAHUT CONREUR, shows the following values:

- crude 294.3 N

- 686.7 N after 24 hours drying at room temperature

- 1 hour at 100 ° C and 1 hour

After drying at 130 ° C, 1765.8 N.

The briquettes are then immersed in cold water. It can be stated that they disintegrate very quickly. In a few minutes, the briquette no longer shows cohesion.

These results show that using only one starch-based binder can produce briquettes with good mechanical properties but not waterproof lump carbon.

Example 2

The present invention is a charcoal based briquette

In a mixer, 50 kg of charcoal, which has the same characteristics as that of Example 1, and 2.5 kg of native wheat starch are well blended. The resulting mixture was heated to 50 ° C with stirring. Add 25 g of ammonium persulfate diluted in 2.5 L of water. The mixture was stirred for half an hour while raising the temperature to 90 ° C; the final moisture is then 8%. The mixture is then compressed by compaction under the conditions described in Example 1.

Thus, we obtain briquettes that have raw enough cohesion to withstand transport. The product was dried at 220 ° C for 2 hours.

The strength of the briquettes, measured according to Example 1, shows the following values:

- crude 200 N

- 1300 N after drying for two hours at 220 ° C

The briquettes are then immersed in cold water. There is no collapse even after months of diving.

The strength of the briquette remains unchanged after soaking in water and no surface damage is observed even after soaking.

This example demonstrates that the addition of 5% native starch and 0.05% ammonium persulfate relative to the dry weight of the fuel block makes it possible to produce briquettes that meet the technical requirements for strength and water resistance.

Example 3

The present invention is a charcoal based briquette

To a mixture of lignite and starch identical to Example 2, 50 g of sodium perborate is added under the same conditions and the mixture is subjected to the same treatment as in Example 2. The final moisture of the mixture is the same as in Example 2.

Thus, we obtain briquettes that have raw enough cohesion to withstand transport. The briquette is then dried for 2 hours at 200 ° C.

The strength of the briquettes, measured according to Example 1, shows the following values:

- 350 N crude

- 1100 N for 2 hours after drying at 220 ° C

The briquettes are then immersed in cold water. There is no collapse even after months of diving.

The strength of the briquette remains unchanged after soaking in water and simple draining. No surface damage is detected.

This example demonstrates that the addition of 5% native starch and 0.1% sodium perborate relative to the dry weight of the fuel block makes it possible to produce briquettes that meet the technical requirements for strength and water resistance.

Example 4

- The lignite briquettes according to the invention

100 g of RHODORSIL SILICONATE 51 T water repellant (potassium silicone, sold by Rhone-Poulenc, with a dry weight content of about 49%) are added to a mixture of crushed coal, starch and ammonium persulfate as in Example 2. This mixture was treated as in Example 2. This gives a briquette which has a raw enough cohesion

HU213 316B to withstand shipping. The briquette is then dried for 2 hours at 230 ° C.

The strength of the briquettes, measured according to Example 1, shows the following values:

- crude 200 N

- 1400 N for 2 hours after drying at 230 ° C

The briquettes are then immersed in cold water for 1 hour. During this time, their water re-uptake is only 1.6%.

The strength of the briquette remains unchanged after soaking in water and no surface damage is observed even after soaking.

This example shows that the addition of 5% native starch, 0.05% ammonium persulfate and 0.1% potassium silicone relative to the dry weight of the fuel block allows the production of briquettes that meet the technical requirements for strength and water resistance, and severely limits the undesirable water reuptake of the briquettes.

Claims (9)

PATENT CLAIMS A process for producing a waterproof briquette comprising: - fine particulate fuel, from 0.2 to 25% by weight, preferably from 1 to 15% and more preferably from 2 to 7% by weight of organic binder, and from 0.01 to 10% by weight, preferably from 0.025 to 10% by weight of this fine fuel. 5% by weight and more preferably 0.05% to 3% by weight of oxidizing agent, - mixing the oxidizing agent with either fuel or organic binder or both or a mixture of both, compressing the resulting mixture, and - drying the briquettes obtained by cutting. Process according to claim 1, characterized in that the organic binder used is molasses, cellulose, hemicellulose flour, protein, starch, derivatives or mixtures thereof, preferably starch and starch derivatives. Process according to claim 1 or 2, characterized in that the oxidizing agent is a water-soluble oxidizing agent, for example hypochlorite, perborate, persulfate, percarbonate, bromate, peroxide or a mixture thereof, preferably persulfate, more preferably ammonium persulfate. 4. A process according to any one of claims 1 to 3, characterized in that the compaction process is pelletization, compression compression, extrusion or foundry molding. 5. Process according to any one of claims 1 to 3, characterized in that the drying process uses a temperature of 150-500 ° C, preferably 170-300 ° C, more preferably 190-250 ° C. 6. A process according to claim 2, characterized in that it is an organic binder - use native starch, natural or hybrid, of any origin, such as potatoes, manioc, maize, waxy maize, high amylose maize, wheat and milling products thereof, barley or sorghum, or - use of a physically and / or chemically modified starch derivative. 7. The process according to claim 6, wherein the organic binder is native starch, optionally rendered soluble in cold water by drum-drying and / or gelatinizing treatment. 8. A process according to any one of claims 1 to 3, characterized in that at least one organic silicon-containing water repellent is added to the fine-grain fuel, the organic binder, the oxidizing agent or a mixture thereof. 9. The process of claim 8, wherein the organic silicon-containing water repellant is a compound of formula (I) wherein R and R 1, which may be the same or different, are organic radicals, which compound is preferably a non-reactive silicone oil, silicone resin, reactive, namely, hydroxylated, alkylated, arylated, hydroalkylated, hydroarylated silicone oil, or mixtures thereof, or emulsions thereof; or a silicone of formula (II) wherein - R ₂ is alkyl, alkenyl or aryl, X is an alkali metal or alkaline earth metal atom and - 1 <n <10, preferably potassium silicone.