CS227902B1 - A method for producing non-agglomerating powder and / or crystalline products - Google Patents

Abstract

Method for producing non-agglomerating powder and crystalline products using water-insoluble or sparingly soluble anti-caking additives based on condensates of urea with formaldehyde under the catalytic effect of strong acids (HNO-). Their essence is mixtures of trimethylenetetraurea to hexamethylenehapturea and cyclic condensates, e.g. 2-keto-5-carboxamide-1,3>5-perhydrotrilazine. These anti-caking additives are applied in an amount of 0.001 to 15 (0.2 to 3) parts by weight per 100 parts by weight of powder products.

Description

227902 2

BACKGROUND OF THE INVENTION The present invention relates to a process for the production of non-agglomerating powdered crystals or crystalline products used as extinguishers, fertilizers and intermediates for the production of explosives using anti-caking agents.

The formation of agglomerates is an unpleasant property of some of the substances used in the production of explosives, artificial fertilizers and powdered extinguishers, which occurs during storage as well as mechanical operations with these substances.

The amount of lumps, as well as the strength, is determined by various factors, most often by the size of the crystals, by the shape, the moisture content, the pressure under which it is stored, the storage time, the temperature fluctuations, the electrical moisture, or the shelf life. the possibility of creating a static charge and so on.

The most frequent agglomeration of particles, resp. "sintering" makes the crystal crystals moisture, the solution formed in a direct manner evaporates and combines the primary powder or crystalline substance with a solid recrystallized solid phase layer.

The mechanism of the agglomeration can be explained by the fact that the adsorbed moisture forms a saturated solution on the surface of the crystals which accumulates in the places of contact of the crystals due to capillary forces. The fluid blisters thus formed, the abundance of capillary forces, attract further crystals to each other, thereby creating larger clusters. Under the influence of the external conditions advantageous for the crystallization of a number of substances from saturated liquid-liquid-forming solutions, recrystallization and thus agglomeration, respectively, occur. "sintering" of the agglomerates formed. The cause of the primary moisture of the substance is generally its insufficient drying. The secondary humidification is in turn the result of the hygroscopicity of the product, due to the moisture content of the air and temperature fluctuations. At elevated humidity, the water is adsorbed on the surface of the crystals, and there is no evaporation and sintering of the crystals, i.e., clumping of the substance, when the air humidity drops. The "sintering" speed depends on the water absorption rate, which is caused by the quality of the material, the moisture and the surface of the crystals, the diffusion and adsorption processes, the air exchange of the system and the like. One possible method of avoiding sintering would be to pack good dried crystals in a dry atmosphere and prevent external air from accessing the storage time.

However, this situation is almost impossible from operational sources. Another method that can be manipulated by the process is to dry the hot product and quickly pre-cool it. The chiller can be used for cooling, but cold air is used.

A less effective method for avoiding caking is to reduce the number of intercrystalline contacts, which can be achieved by producing crystals of approximately the same size and shape.

Their absolute size is not the primary concern but the shape. In this way, relatively few points of contact between the crystals are obtained, as the interstices between the crystals are discharged, for example, by a dust fraction. In addition, well-developed and equally well developed crystals are also better rinsed and dried, have better creep characteristics and, last but not least, the product is also aesthetically pleasing.

To a great extent, additions of other substances have been used to prevent the clumping of substances, and have been paying close attention to the suitability of using cutting ingredients. In principle, these additives can be divided into substances which are capable of absorbing or absorbing moisture even more than the crystalline or powdered product and on the substances which produce a hydrophobic film on the crystals which prevents water from entering the crystalline material. It is generally known to use inorganic alkali metal salts as anti-caking additives, in particular sodium carbonate and bicarbonate, bicarbonate and potassium carbonate, as halides, sulphates, dichromates, phosphates and the like as extinguishing powders which need to be protected from agglomeration. This is accomplished by combining the individual active ingredients, e.g., by using a burnt clay (auto-certified USSR 275,562), a mixture of sodium bicarbonate mixed with disodium carbonate (U.S. Pat. No. 4,488,621) and phthalocyanines (U.S. Pat. No. 3,531,407). Urea is also applied to these (U.S. Pat. No. 3,484,372). Further known (U.S. Pat. Nos. 3,536,620, 3,607,744 and 3,776,843) are the preparation of the extinguishing agent empirical formula MCgNgH10Oi wherein M is an alkali metal obtained by reaction of urea with compounds of alkaline nature such as hydroxides , alkali metal carbonates and bicarbonates. It is also known (U.S. Pat. No. 3,464,921) to use calcium lignosulfonate, ferric oxide, sodium tetraborate, dry sodium chloride, potassium chloride, chloridubarate, as well as tricalcium phosphate, sodium bicarbonate, and talcum powder. Also of interest is the use of cresol-formaldehyde resin in a mixture with asbestos flour (U.S. Pat. No. 146,521) as well as powdered polyvinyl chloride against caking of inorganic dusts (auto-certificated USSR 258 042 and 379 212). Anti-caking agents also include cellulose ethers (U.S. Pat. No. 3,613,088) and hydrophobizing agents such as stearic acid addition salts. synthetic resins, paraffin, etc. [jeremenko N. E., Svetlov B. J .: Theory and Technologist! izdat, Moscow (1957) 3 · In the case of industrial explosives containing ammonium nitrate, sodium nitrate, nitrate and potassium chloride, which may also have taken up moisture, thereby exacerbating explosive properties (threatening to harden the charge, reduce detonation capability, etc.) the problem is solved by packaging the ingredients in a water-impermeable material (U.S. Pat. No. 737,255; French Pat. No. 1,001,335; German Pat. Nos. 938,594 and 940,693).

Most often, paraffinizing of cartridges of explosives is used. However, the less laborious use of plastic packs for packaging cartridges or a combination of paper and plastic foils, possibly water impermeable coatings, is increasing. However, the disadvantage is the high quality, especially the compactness of the coatings, as well as the fact that the fabrics are coating the surfaces with impurities.

Similar disadvantages of "contamination" are also applications in water-swellable substances such as casein, dextrin, polyvinyl alcohol, gelatin and the like. (NSR Pat. 932 595 and 939 440) as well as water soluble dyes such as fuchsin and 1,4-diaminoatrantrachinone-2-sulfonate [jvhetstone J.:Ind. Chem. 401 (1949): ii, 2663 (1952)]. Coloring agents do not color the product.

Water-adsorbents such as silica (V. Brit par. 1 014 904), alkaline earth oxides, mineral acid salts and alkaline earths, especially sulphates and phosphates [jap. pat. 74 20 200 (1974)], boron-containing substances such as boron oxide, boric acid, borates and the like. The disadvantage of these inorganic admixtures is the ash content of the final product.

It is also known to use an emulsion of stearic acid and a non-ionic surfactant (U.S. Pat. No. 121,974) as anti-caking additives of hexamethylenetetramine, benzoic acid acylate and its derivatives (French Pat. No. 1,382,816; U.S. Pat. No. 2,912,435; Pat. 810 765), calcium stearate and magnesium stearate (Pat. V. Brit. 1 014 904 and French Pat. No. 1,382,815).

High molecular weight, at least partially water-soluble or at least water-swellable substances have considerable advantages. aut. Certificate No. 205 440 and 205 611)]. However, their application is substantially limited to hexamethylenetetramine. However, in spite of their evident advantages and the particular application of hexamethylenetetramine, the non-toxic and available anti-caking additives may not be optimally optimized. In contrast, the production of neaglomer-227902 powdered and / or crystalline products and the use of relatively versatile anti-sintering additives can be accomplished according to the present invention.

According to the present invention, a process for the preparation of non-agglomerated powder and / or crystalline products by crystallization associated with the separation and / or treatment of these products by modification of anti-caking additives in the reaction solution and / or in the subsequent stages of manufacture, optionally also by refining, is carried out as anti-caking agents single or sequentially water-soluble and / or insoluble products of acid or acid-catalysed condensation of urea with formaldehyde, preferably trimethylenetraurea, up to hexamethyleneheptamea and / or 2-keto-5-carboxamide-1,3,5-parhydrotriazine, in an amount of 0.001. to 15 parts by weight of the solid phase, followed by homogenization. The advantage of the process according to the invention is, on the one hand, the technical availability of antiseptics, their universal use. The method of production does not require technically more sophisticated auxiliaries and products are obtained only with mild ash content. The increase in the case of hexamethylenetetramine, even from the point of view of special applications, is virtually non-polluting due to its chemical composition and reactivity with hexamethylenetetramine. The combination with other anti-caking additives is not excluded by the mechanisms described in the preceding section.

According to the invention, the subsequent stages of production are understood to be drying, thickening, crystallization, recrystallization, refining, drying, drying, before packing, filling, before dispatch.

According to the invention, the anti-caking additives added are the product! the reaction of urea and formaldehyde in an acidic environment. Thus, they are predominantly mixtures of triethylenetetramurea and hexamethylenepeptamurea, respectively. cyclic polycondensates. They do not derive from the starting homogeneous ratio of urea to formaldehyde of 0.8 to 1.8, preferably of 1.0 to 1.3 in the presence of 0.001 to 0.010 mol of mineral acid per mole of urea, preferably in the presence of 0.004 to 0.005. mole of mineral acid per mole of urea and reaction temperatures up to 70 ° C.

The most effective form of isolation of these condensers (from their application according to the invention) is the drying of the reaction mixture in a nebulizer. This gives a very fine product (a product with a fine grain size), that is to say with a large surface area, practically insoluble in water and only slightly soluble in conventional organic solvents. the more violent details of the method of manufacture of the present invention, as well as the advantages are exemplified. Example 1

The urea condensation product with formaldehyde I is prepared so that 800 wt. the moieties (e.g., 12.320 moles) are dissolved in 1800 wt. parts of water. To this solution, 900 wt. part of an aqueous formaldehyde solution containing 40.7 wt. of formaldehyde (e.g., 12,198 moles of formaldehyde). To the obtained mixture is added 27.93 parts by weight of nitric acid with conc. 20.3 wt. (e.g., 0.072 moles of nitric acid). After a reaction time of 18 minutes, the reaction mixture reaches the highest temperature of 68 ° C.

The mixture was then cooled to 50 ° C, adjusted to pH 4.5 with aqueous sodium hydroxide solution conc. 20 56 wt. The neutralized reaction mixture was further added to the dryer scrubber with an inlet temperature of 200 ° C; dosing of the mixture is made such that the temperature of the outlet gases is 85-90 ° C. 920 wt. parts of the product in the form of a fine powder with an additional 25 wt.%, the portions are collected from the stream of leaving gases from the dryer. 5 227902

By means of differential thermal analysis (DTA), operating at weighs of about 0.1 g and a linear temperature rise rate of 60 ° C / min, the product has these values; initial solid phase endothermic change at 114.4 ° C and peak at 125.0 ° C; solid phase initendermal decomposition at 240.0 ° C with peak at 253.9 ° C. Example 2

The urea-formaldehyde II condensation product is prepared so that 800 wt. parts of urea (e.g. 13.320 moles of urea) are dissolved in 1800 wt. of water and 780 wt. parts of an aqueous formaldehyde solution specified in Example 1 (e.g., 10.571 moles of formaldehyde). To the solution mixture at 17 ° C was then added 22.3 wt. 20.3 wt. (e.g., 0.057 mol of nitric acid).

After a reaction time of 45 min, the mixture reached a maximum temperature, i.e. 56 ° C. After cooling to 32 ° C, the liquid was removed to give 1 407.1 wt. parts of a filter cake with a content of 48.6 wt. water. Drying the filter cake at 70-74 ° C for 48 h (in a thin layer) yields a product in the form of lumps of Tahko sa rozpadsjúcichne fine powder.

With DTA as in Example 1, the following values were also determined for this condensate: the initial solid phase endothermic change at 104.4 ° C and its peak at 110.0 ° C; early second, little pronounced elongated endothermic change in solid phase at 115.5 ° C and its peak at 124.6 ° C and the onset of solid phase endothermic decomposition at 234.5 ° C. Example 3

To 10 kg of 55-60 ° C dried MaHCO 3 powder, add an anti-caking agent of 100 g of urea-formaldehyde condensate I prepared according to Example 1. Mix dry at 15-25 ° C dry at 15-20 ° C. The sample and the time of 6 months show a tendency to form lumps in the enclosed box and boxes to bond. In the comparative sample without the addition of an anti-caking agent, a soft layer is formed during the aesea and is firmly attached to the bottom of the box. EXAMPLE 4 20 kg of granulated ammonium nitrate with a grain diameter of 2.5 mm is divided into two parts. 300 g of urea condensate with formaldehyde in the acidic environment II prepared according to Example 2 are mixed into the first part and stored for 3 months in polyethylene bags at a temperature not exceeding 25 ° C. Only in the second part, without the addition of anti-caking agent, the agglomerates will show after 3 months. A DAP explosive consisting of 94.5 wt. ammonium nitrate and 5.5% fuel oil L. At the same time of homogenization in the mixer, the explosive heat is reduced in the ammonium nitrate explosive without the addition of anti-caking agent compared to the explosive with the addition of 3.75 MJ / kg to 3.55 MJ / kg. Example 5

Weigh 500 g of trisodium phosphate for 60 h at 55 to 60 ° C. The plurality of shells are packed in a polyethylene bag after cooling, the other half being stored on filter paper. In both storage cases, agglomerated trisodium phosphate lumps are observed after several hours. 227902 Example 6

The procedure is similar to Example 5, except that the condensate I prepared according to the example is added to the trisodium phosphate crystals in an amount of 2 wt. parts. There is no clumping and no leakage for 4 months in the stored samples. Example 7

Similar results to Examples 5 and 6 are also obtained with sodium nitrate. EXAMPLE 8 25 g of crude technical hexamethylenetetramine containing 1.31% by weight of moisture are adjusted by adding 2% by weight of the urea condensate with the formaldehyde of Example 2. The resulting mixture is dried at 100 DEG to 109 DEG C. and wrapped in polyethylene at room temperature. -new bags. The 4 snuff-sealed bags thus prepared are placed on top of each other and stored. No hexamethylenetetramine sintering occurs within 5 months. Example 9 To an aqueous suspension! hot 60 ° C by conc. 90% by weight of the hexamethylenetetramine from the concentration of the reaction mixture after ammoniacalization of the formaldehyde solution is added to every 900 parts by weight of a suspension of 7.7% by weight of the urea-formaldehyde condensate filter cake prepared by Example 2. Centrifuging the "mother" liquors and washing the filter cake with saturated a solution of hexamethylenetetramine (urotropin) followed by drying in an oven with a flow of air of 69 to 70 ° C yields a product containing 1.9% urea-formaldehyde condensate II.

In fact, the urea-formaldehyde condensate filter cake is first mixed in a small amount of suspension before it is added to the container trough before the centrifuge. centrifugation is obtained by "mother liquor" turbid by the presence of condensate passing through the filter cloth. Example 10 To 1000 kg of hexamethylenetetramine in a homogenizer, 3% by weight of trimethylene tetramurea are added. The mixture is then homogenized for 1.9 h. Then, 900 kg of product is passed through the sieve to automatic packing weight and the packaged product is placed on a pallet. The rest is ground in the mill. The milled hexamethylenetetramine is carried from the mill by a stream of docyclone, where the hexamethylenetetramine is separated from the mill and automatically packaged and the packaged product is placed on a pallet. The product on pallets 3a does not sinter even for 9 months of storage Example 11

Weigh out 100 g of hexamethylenetetramine and add different types and amounts of urea derivatives as anti-caking agents (phlegmatizers), respectively. urea products with formaldehyde in acidic medium, in the form of aqueous solutions. Sample processing is similar to Example 8. The results are summarized in Table 1. 7 227902

Reaction products of urea with formaldehyde for the catalytic effect of mineral acids Added amount (% by weight / hexamethylenetetramine) Time to start agglomeration ("sintering") hexamethylene etramine - (without additive - reference) after 10 days the agglomeration begins to condense product I 1, 31 did not start for 5 months condensation product II 3.00 did not start for 5 months trimethylenetetramurea 1.10 did not start for 5 months hexamethylenepepteamea 2.00 did not start for 5 months 2-keto-5-carboxamide - 1,3,5- Perhydrazine 1.5 did not begin for 5 months Example 12

Samples of 500 g of phosphate were weighed and condensate I (foam type) was added to the individual samples in different amounts. The results obtained are summarized in Table 2. T and b'u I k and 2

Phosphates species Added amount (% w / w phosphate) Time to start agglomeration ("sintering" phosphinate) phosphate without additive - after 5 days began disodium - reference agglomeration phosphate without additive - after 5 days started dibasic - reference agglomeration disodium phosphate 2 , 00 did not start during the two months, dipotassium phosphate 2.00 did not start during the months

Claims (1)

SUBJECT OF THE INVENTION The process for the production of non-agglomerating powder and / or crystalline products by crystallization associated with the separation and / or treatment of these products by modification with antimicrobial additives in the reaction plant and / or subsequent production steps, if appropriate, is characterized by as anti-caking agents, single or sequentially water-soluble and / or insoluble products are added to the acid or acid-catalysed urea condensation with formaldehyde, preferably trimethylenetetraurea and hexamethylenepeptamurea and / or 2-keto-5-carboxamide-1 , 3,5-perhydrotriazine, at 0.001 aS 1? wt. parts, calculated on 100 wt. parts of the solid phase with subsequent homogenization. Severografia, n. P., Mos Price 2,40 Kcs