CS261516B1 - Process for preparing granulated industrial salts - Google Patents

Abstract

The method is performed by compression on double roll compactor, or melt before or after compression in an amount of 0.5 to 35 wt. and drying heat transfer medium at 80 ° C up to 230 ° C.

Description

The present invention relates to methods for preparing grants

Other industrial 's are Κ0ιημτ ^ η6φθ |. - *

Emulsion granulation is important (an important technological operation to ensure good physical-mechanical properties of the product, in particular dimensional strength and abrasion resistance, in particular dimensional homogeneity. These properties are required for high-tonnage products, in particular for industrial fertilizers. technological granulation processes are granulation in a single or double spindle granulator, drum, plate and fluid granulator.

These processes are generally known, described in literature and cited in a number of patents such as: NSR 2,436,863, 1,442,605, 2,711761,

317,129, 2,418,552; USSR 375,089, 456,008, 805,033, 461,079; AUSTRALIA 443 715; DOS 1,792,206 and others.

Their principle is based on granulation of the melt or solution of salts under defined conditions, so-called. temperature-humidity ratio, under which conditions the optimum ratio of liquid and solid phase is adjusted. recycle. In general, these processes are heat and machinery intensive, since the ratio of liquid phase to recycle varies from 1: 2 to 1: 3 depending on the type of salts to be treated and the granulation efficiency. An integral part of these processes is the efficient sorting of the polydisperse granulate into a commercial fraction and the crushing of the oversize fraction. At 40-50 tons / year, the circulation-ballast material in the form of 100-160 tons of recycled material is required per year, which presents a number of technological problems and considerable energy requirements. Certain substances are not preferred to be granulated in such a manner, and as long as the process permits, granulation is chosen by spraying the melt into a cooling environment, typically air, oil, or other inert liquid. These processes are reported by m. i. in the French patents 2,359,635; DOS 2,308,061, 2,218,218, 2,409,695; NSR

941 460, ČESKOSLOVENSKA 154 161. Also this procedure is not universally applicable, its main drawback being the low mean diameter of the granules. Although the process of uniform granulometric composition is technically and technologically mastered by new types of granulating nozzles, increasing the diameter requires increasing the height of the granulating towers, which makes these processes less investment advantageous. Oil pelleting from ecological and energy sources and from the perspective of safety is rarely applied. In some cases it is possible to solve the process of granulation from melts by spraying into the gas stream containing solid particles according to European patent 26 918. optionally by pouring and heating by patent DOS 1 592 734 or by extrusion, see French patent 1 440 889. Technologically advantageous as from energy In the present invention, the technique of granulation by compression and not of a dysalgic compactor is presently applied. This technology allows the dispensing of virtually all inorganic extracts of organic matter in the powder or crystalline state. This process is disclosed in US Pat. No. 831,163, French Patent 2,004,278; This process, in combination with dimensional disintegration and sorting, will ensure adequate homogeneity of the granulometric composition at low cost, minimal recycling, corresponding only to the formation of disintegration and sorting dust. Energy requirements are minimal and outputs correspond to 60-80 ° / output product output. The disadvantage of this process is that only the cohesive forces of the individual particles in the compression process are used in the granulation process, as a result of which the granulate has a low abrasion resistance and a lower point strength. For some products, especially of high-tonnage character eg. In the case of industrial fertilizers, where multiple handling and higher storage pressures are expected at the same time, the application of this procedure is limited or possibly excluded. Isobutylidene, diurea, calcined phosphates, alkalis, mineral heavy oils according to Japanese patent 81005719, or wetting with a solution or emulsion of a polyvinyl resin according to German Patent No. 2,023,502, or adhesive formation are used to eliminate the reported negative properties of the granulate. between granulated particles using emulsions (Meded fac. land bouwwetensch;

rijksuniv gent 1972, 37, 3938-54). A disadvantage of the above processes is that the components other than the composition of the granulate are introduced into the granulate, the binders being relatively expensive and in some cases environmentally undesirable and technologically unacceptable.

It has been found that these disadvantages can be solved by the process according to the invention, which comprises treating the salt mixture before or after compression with a solution or melt of the mixture of these salts or one of the components of the mixture in an amount of 0.5 to 35 wt. . %. The compressate is dried at a drying medium temperature of 80-230 ° C.

According to the process of the present invention, due to the solidification of the contact points, the crystalline overgrowth of the individual particles of the compressor results in higher abrasion stability and granular strength, corresponding to values close to the granulates prepared by conventional granulation processes. j. low energy and investment demands. In combination with the process of the invention with conventional granulation processes, such as pre-granulation of the working portion and / or recycle, higher granulation efficiency is achieved with a sharper granulometric composition of the wet granulate exiting the classic granulators. it

S allows simple adjustment to intensify the performance of existing equipment with higher product quality and, under certain conditions, also reduce recycling.

Example 1

To a urea / ammonium sulphate mixture compressor with a content of 28% by weight. and the granules average diameter of 2.5 mm with a strength of 4.5 N 52.6% obrusivosťou with stirring, treated with a saturated solution of urea at 30 ^Q C in an amount of 2% by weight. In the resulting granulate, the point strength was increased to 6.5 N and the abrasion increased to 87%.

Example 2

Compressed with a mixture of urea, ammonium sulphate and dolomite containing 26% w / w. N, a mean granule diameter of 2.5 mm, a strength of 3.3 N and a abrasion of 36.6 wt. 1% by weight in a rotary drum. 70 pere. solution of urea. The point strength increased to 4.7 N and the abrasion grew to 77.3%.

Example 1 and d 3

Per 100 kg of blend containing 66 wt. % ammonium sulfate, 20 wt. urea, 14 wt. Dolomite was charged in a mixer with 3.5 kg of saturated ammonium sulfate solution at 20 [deg.] C., which was then compressed on a two-cylinder compactor. The compressate was dried in a stream of 85 ° C warm air. A granulate having a point strength of 5.1 N and a wear rate of 76% was obtained.

Example 4

The NPK fertilizer 12 - 19.5 - 19.5 of the cyclones was compressed on a two-cylinder compactor to a granulate with a mean granule diameter of 2.5 mm, a strength of 4.1 N and a abrasion of 50.1%. This pregranulate was granulated with a recycle at a ratio of 1: 17 in a twin-screw screw granulator, while the NPK 12-19.5-19.5 melt was impregnated in an amount of 30% by weight, after which the granulate was dried in a hot air stream of 220 ° C. The proportion of commercial fraction 2-4 mm increased proportionally to the amount of compressed feed. Mean values of point strength and abrasion resistance were virtually identical to those of the product without the use of pregranulate.

Claims (2)

Process for the preparation of granular industrial salts by compression on a double-roll compactor, characterized in that, before or after compression, a mixture of these salts or one of the components of the mixture in an amount of 0.5 to 35 wt. 2. A process according to claim 1, wherein the compressate is dried at a drying medium temperature of 80 to 230 [deg.] C.