MXPA98002789A - Formation of briquetas de finos de mine - Google Patents

Abstract

Thin or fine, for example fine minerals such as carbon often are agglomerated as briquette or tablet structures by a cold roll pressing operation using as a binder a resinous resin of alkaline phenol cured together with an oxyanion, to improve strength or resistance in cru

Description

FORMATION OF MINERAL FINE BRIQUETTES DESCRIPTION OF THE INVENTION This invention relates to the formation of briquettes of fine material, for example, mineral fines, particularly coal fines, which we will often call carbon. The giblets are agglomerated into tablets or briquettes by a cold roll pressing operation, using as a binder, a resin resin of alkaline phenol formaldehyde cured with ester together with an oxyanion to improve the green strength. A variety of techniques are known to produce agglomerated structures, such as briquettes or often carbon tablets, the most popular method is to form ovoid forms by a cold roll pressing operation. In this case, the carbon lumps blended with a binder or binder are crushed at pressures up to 2.1 x 106 kg / m2 (3000 psi), between two metal rollers having ovoid depressions. The briquettes thus formed, fall from the press into a transformer band to be taken to storage and subsequent packing. Several types of binder have been used in this process with different sides of success. For example, sodium silicate gives moderately strong briquettes, but it has poor water resistance and due to the increase in ash content reduces the value as coal fuel. Binders such as bitumen sulfite bleach, result in the emission of vapors and smoke from the burning briquette, which is clearly undesirable. The use of resole phenol-formaldehyde resin cured with ester is known to give moderately strong briquettes with good burning properties and US Patent 4,802,890 is an example. However, a raw strength additive commonly cotton should be used to provide a very premature strength or resistance, so that the finished ovoid can fall intact to the conveyor belt. Starch is susceptible to bacterial and fungal attack, and therefore, must be used with a biocide or fungicide. In addition, the starch inlay can decrease the force achievable from the phenolic resin, from the point of view of the mechanics of the invention, this system is complex due to the need of four components. There is therefore a need for a binder or binder for charcoal giblets which substantially avoids these disadvantages. In addition, the problem is often not confined to coal, since there is also a need to agglomerate fines from a variety of minerals, either in the form of particles or fibers. According to the invention, in one embodiment, a curing binder at room temperature for agglomerating mineral fines comprises, a phenol formaldehyde resin alkaline resin a co-reactant ester and an oxyanion to improve the strength and strength in the raw, also according to the invention, there is provided a method for agglomerating often such as the small one is bound in larger agglomerates by a binder comprising an alkaline formaldehyde phenol, a co-reactant ester and an oxyanion, to improve the green strength. Thus, we have found that the inclusion of certain oxyanions, in particular borates, as a third component rapidly increases the resin resin viscosity, and thus improves the strength of the system. This allows the briquette to fall intact on a conveyor belt. The rapid increase in viscosity is believed to be the result of a decrease in pH, of the resin coupled with the ionic crosslink between the methylol groups in the phenolic resin and the oxyanion. For example, the addition of 3% by weight of tetraborate resin can increase viscosity up to four times. The binder can be supplied as a briquette binder system for bonding giblets such as mineral giblets and particularly carbon giblets at ambient temperatures, comprising a separate component: a) a phenol formaldehyde resin alkaline resin; b) an ester co-reactant; c) an oxyanion to improve the strength of the resultant resulting crude to mix together with the petite and form a mixture to be formed in briquettes. This system may have an indication that the resulting bond is useful for fine briquettes, particularly mineral fines such as coal. It can be supplied with the components in separate containers that can be of a relative size, so that many of the contents of the containers with the giblets provide a resulting mixture where the components are in desired proportions, unlike previous systems that include an organic material such as cotton, the resulting briquettes of the invention, are not susceptible to decay and growth of bacteria. Therefore, they do not need to include a fungicidal bactericide and remain bright and free of decay during storage. The phenol formaldehyde resin alkaline resin can be, for example, prepared by reacting a monohydric phenol such as phenol or cresol or a dihydric phenol such as resorcinol with formaldehyde under alkaline conditions. The molar ratio of the monohydric or dihydric phenol to the formaldehyde can be from 1: 1 to 1: 3, but the preferred range is 1: 1.6 to 1: 2.0. To this reactant mixture an alkaline material is added as a solid or in an aqueous solution. Sodium and potassium calcium hydroxides can be used, but the latter is preferred, the amount of solid base added can be between 8 to 18%, more preferably 12 to 18% by weight of resin although the preferred range is 11 to 15. % by weight of the resin. The co-reactant ester (curing agent) may be the acetic acid esters of ethylene glycol, propylene glycol, cutylene glycol and glycerol, lactones, such as propriolactone, gamma-butyrolactone and carbonate esters, such as propylene carbonate and mixtures thereof. ethylene / propylene carbonate. Mixtures of these can also be used. Suitable oxyanions are borate, aluminate tin, although borate is preferred, also the oxyanion may be present in the form of a salt, such as the potassium salt, or sodium salt. The amount of alkaline phenolformaldehyde resin to be added to the giblets such as those of charcoal, will normally be from 1 to 6% by weight of the petite, the amount of the curing agent being from 15 to 25% by weight based on the weight of the resin. The oxyanion that can be conveniently added as a 5% solution will usually be added in an amount of 1 to 6% by weight based on the small amount. These amounts are generally greater than the amounts that would be needed for particles of larger size than the giblets.

The preferred order of addition of the mineral giblets, is to add the oxyanion first, then the ester and finally the resin, giving time between each addition to disperse the component in the mixture. The agglutination will take place at room temperature and no separate heating of the components is required. Thus, in the case of forming briquettes or briquettes of coal giblets, little or no change is required for the cold roller pressing operation except the use of a binder or binder according to the invention, instead of traditional binders such as Sodium silicate and normally the carbon giblets will be in the form of a wet mixture to avoid dust problems. In addition, of the coal mints, the agglomeration process of the present one, can be used with other types of giblets, for example coal and graphite, with giblets or fine minerals, for example quartz, calcium silicate, and aluminum silicate; and other fine ones. Mixtures of fines, for example mixtures of various fines based on carbon and silicon fines are also possible. The coal and other fines will normally have a maximum size, so that they will pass a mesh of an opening of 5mm square, and preferably a mesh of an opening of 3mm square. The fines will therefore contain, a margin of particle size that reaches up to 10 of the maximum indicated above. More preferably, the fines are from a maximum size range of 150 to 200 mesh. In some circumstances it may be desirable to add a silane to aid agglomeration between the binder and the mineral, and an example is quartz. The silane if present is preferably added in an amount of 0.1 to 1.0% by weight of the resin. Example, the invention can be shown by the following example: A resin of phenol formaldehyde resin is prepared by reacting under mild alkaline conditions 450g of phenol and 270g of 91% paraformaldehyde, in the presence of 351g of water for 15min. at 100 degrees C, after cooling to 80 * C, 93g of potassium hydroxide (45% pp / p aqueous solution), is added and the reaction is continued at 80 ° C until the viscosity has increased to 17A, The Paint Research Association Bubble Tube C25 C). After cooling the reaction mass 325 g of potassium hydroxide (45% w / w aqueous solution), they were added. Finally 4g of gamma amino propyl ethoxy silane was added, the final resin has a viscosity of 350 c.p. (Brookfield EPV-8 C20 ° C / spindle 4/100 rpm) and a solids content of 53% (3h C20 ° C). A mixture of coal often comprising 70% anthrasite, 20% petrochemical, and 10% bituminous material with a moisture content in general of 8.5% was mixed with 3% by weight of a 5% aqueous solution of tetra sodium borate followed by 1% by weight of an ester comprising equal parts of triacetin and gamma-butyl lactone. The resin was prepared as above by adding 4% by weight based on the giblets and dispersing for one minute. This mixture was formed into briquettes by the roller pressing technique, the ovoids thus formed remained intact when falling from the press. The measurement of the resistance or force in crude at 30sec. of the molding, gave values of approximately 2.46 x 10 * to 2.16 x 10 * kg / M2 (35 to 45 lb / in.). After 24 hours, the briquettes had good scrap hardness having increased the compressive strength to approximately 9.84 x 10 * to 1.12 x 105 kg / m2 (140 to 160 psi), and the immersion tests showed that they were resistant to water. The burn tests showed that the briquettes had excellent heat resistance and produced very little smoke or vapors. The previous exercise of forming briquettes was repeated with the 5% aqueous solution of sodium tetra borate, replaced on a weight-to-weight basis by 3% water alone. 70% of the ovoids disintegrated when falling from the roll press showing little evidence of any measurable oil resistance.

Claims (12)

R E I V I N D I CAC I O N S

1. - A binder or binder for curing at ambient temperature and agglomerating fines of material, for example, fines or ore fines, comprising a phenol formaldehyde resin alkaline resin, an ester co-reactant and an oxyanion to improve the green strength. 2.- A briquette binder system for agglomerating fines at room temperature, comprising as separate components: a) a phenol formaldehyde resin alkaline resin? b) an ester co-reactant; and c) an oxyanion to improve the green strength of the resulting binder which is to be mixed together with the giblets to form a mixture to be formed into briquettes. 3. A binder or binder according to claim 1, or a system according to claim 2, wherein the resin is one that has been formed by reacting a monohydric or dihydric phenol with formaldehyde under alkaline conditions, and wherein the molar rates of the monohydric or dihydric phenol with respect to the formaldehyde are preferably 1: 1 to 1: 34. - A binder or a system according to claim 3, wherein calcium hydroxide, sodium or potassium, provides the necessary alkaline conditions and is present in an amount of 0 to 18% by weight of the resin. 5. A binder or system according to any of the preceding claims, wherein the co-reactant ester is an acetic acid ester, a lactone or a carbonate ester and wherein the amount of ester co-reactant is preferably 15 to 25% by weight of the weight of the resin. 6. A binder or system according to any of the preceding claims wherein the oxyanion is a borate, aluminate or stannate. 7. A binder according to any of the preceding claims wherein it further includes a silane preferably an amount of 0.1 to 1.0% by weight of the resin. 8. A binder according to any of the preceding claims wherein the binder is bound in larger agglomerates by a binder comprising an alkaline formaldehyde phenol, an ester co-reactant and an oxyanion to improve the strength or strength in the raw . 9. A method for agglomerating fines or giblets wherein the fine is bound in larger agglomerates by a binder or system according to any of claims 1 to 7. 10. A method according to claim 8 and 9, where the fine is coal and the larger agglomerates are ovoid briquettes formed by a cold pressing operation. 11. A method according to claims 8 to 10, wherein the resin is added to the petite in an amount of 1 to 6% by weight of the petite and the oxyanion in an amount of 0.05 to 0.03% by weight of the petite. 1

2. A method according to any of claims 8 to 11, in which the oxyanion is first added to the fines or giblets, then the ester co-reactant and finally the resin is added, allowing the aggregate component to be added. Disperse in the mix before another component is added again. SUMMARY Thin or fine, for example fine minerals such as carbon fines are agglomerated as briquette or tablet structures by a cold roll pressing operation using as a binder a resole resin of alkaline phenol cured with ester in conjunction with an oxyanion, to improve the strength or resistance in raw.