SU1571043A1 - Method of obtaining potassium oxide-magnesium fertilizer - Google Patents

Abstract

The invention relates to the production of potassium magnesium fertilizer by processing salt waste from the production of magnesium and chlorine by the electrolysis of a melt dehydrated in salt furnaces or carnallite chlorinators, and improves the quality of the fertilizer, increasing its storage time while reducing the degree of environmental pollution. The method includes mixing ground electrolyzed melt electrolysis and sludge from carnallite chlorinators or salt-tapping furnaces with sublimates and dust generated during the dehydration and electrolysis stages of carnallite, moistening the calcium mixture containing chlorine gas scrubbing at these stages until the moisture content of the mixture reaches 13- 20% granulation of the mixture, heat treatment and cooling of the finished product in a fluidized bed with the return of the retour to the mixing stage. The salt waste is mixed until the amount of magnesium in terms of magnesium chloride equal to 10-25% is reached in the fertilizer, and the effluents of gas scrubbers in an amount that provides the content of calcium chloride in the fertilizer in the range of 0.5-5% are applied to moisten the mixture. Heat treatment of the mixture in a fluidized bed is carried out at 150–250 ° C and the heat carrier velocity is 1–6 nm / s. The method allows to increase the strength of fertilizer granules up to 90% and increase its shelf life up to 1.5 years. 3 hp f-ly, 1 tab.

Description

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with

The invention relates to the production of potassium magnesium fertilizer from chlor-magnesium production waste by electrolysis of carnallite melt. Salt wastes from this production are spent electrolyte and sludge from magnesium electrolyzers, sludges of carnallite chlorinators and salt-burning ovens for dehydrating carnallite sublimates and dust generated during dehydration and electro, carnallite lysis, as well as wastewater treatment at various stages of this production.

The purpose of the invention is to improve the quality of the fertilizer and increase its shelf life while reducing the degree of environmental pollution.

The method is carried out as follows.

Crushed waste electrolyte of magnesium electrolysis cells, containing,%: potassium chloride 50-75 magnesium chloride 3-10; magnesium oxide up to 1 (the rest is sodium chloride and others), mixed with crushed sludge from carnallite chlorinators or salt furnaces after the second stage of carnaplit dehydration, containing,%: magnesium oxide up to 40, magnesium chloride up to 35, potassium chloride up to 30 ( the rest is sodium chloride, etc.).

The grinding of the spent electrolyte can be carried out by scaling the melt on a drum-type water-cooled crystallizer or by crushing the melt with subsequent sieving it into commercial and substandard fractions.

The maximum allowable particle size sent for further processing by the proposed method is 1.5 mm, with a decrease in the particle size, the granulation efficiency increases. The best results were obtained when melting flaking on a drum-type water-cooled crystallizer. After pneumatic transport, the size of these particles was 0.1-1 mm.

The electrolyte is mixed with sludge in a ratio of 10: (0.2-2), adding gas scrubbing effluents, which are formed at the stages of dehydration and electrolysis of carnallite. Part of the sludge can be replaced with sublimates and dust from chlorine ducts and gas ducts, which exhaust gases from various magnesium production apparatuses: electrolyzers, chlorinators, salt-teak furnaces, etc.

The wet mixture is agitated, granulated (for example, by extrusion), dried and then cooled in a fluidized bed, the air separation section of the retur (fraction less than 1 mm). This fraction is caught (for example, in cyclones) and returned to the head of the process.

Calcium-containing chloride effluents of gas scrubbers contain 50–300 g / l of chlorides, including 2–150 g / l of calcium chloride, 5–50 g / l of magnesium chloride, and 10–50 g / l of potassium chloride (the rest is sodium chloride, etc.) .

The material cooled in a fluidized bed (fraction 1-4 mm) is a finished product — kalimag chloride — granulated mineral fertilizer containing 45–75% potassium chloride, 10–25% magnesium compounds in terms of its chloride, 0.5–5%. 5% calcium chloride, sodium chloride and others. The rest.

The obtained granules have high mechanical strength. Tests carried out according to GOST 21560.3-76 showed that the dynamic strength of the granules is 82-95%, i.e. above 80% required by the specified GOST. This provides an increase in shelf life and a reduction in milling at

0 transportation.

An increase in the strength of the granules is provided by the formation during drying of a very low-melting compound — tachhydrite CaCl2-MgCl z4H40, as well as

5 carnallite KC1-MgCl 6НГО and bischofite HgCl2-6H20.

Reducing the amount of fines is provided by air separation, which takes place as

For example, drying in a fluidized bed, and during subsequent cooling, the classification operation is combined with drying and cooling, which gives an additional effect by simplifying the apparatus.

$ If the content of calcium chloride

less than 0.5%, the amount of melt formed during the heat treatment of CaCl-MgClj 4H20 tachyhydrite in a fluidized bed is not enough for cementation of the main material of the granules, and the required increase in their strength is not achieved. If the calcium chloride content is more than 5%, then the melting of the fluidized bed apparatus takes place, and the normal process is terminated.

In order to form, in addition to tahydrite, still low-melting crystalline hydrates KCl-MgCl2-6H20 and MgClj 6H20, and also to increase the magnesium content in the fertilizer, the amount and composition of the starting components are adjusted in such a way that the resulting fertilizer contains magnesium compounds in terms of its chloride 10-25%.

It was established experimentally that the yield of the product fraction in this case is 91-95% against 85 by a known method.

It has been established that at a temperature in a fluidized bed of less than 150 ° C, the strength of the granules and the degree of their dehydration are insufficient. At temperatures above 250 ° C there is a significant over-, heat consumption.

If the velocity of the coolant is less than 1 nm / s, then the condition is not ensured.

five

0

five

0

steady boiling of granules with a size of 1-4 mm (commercial product). At a speed of more than 6 nm / s, there is a sharp grinding of the granules and the ablation of the material from. lay

The humidity of the initial mixture is maintained in the range of 13-20%.

At a humidity of less than 13% and the use of gas cleaning effluent, granules in the fluidized bed are destroyed due to the low binder content (calcium and magnesium chlorides). Humidification above 20% leads to excessive heat and reduce plant performance.

With the proposed method, the enrichment of the fertilizer with magnesium and calcium is achieved to a greater extent than with the prototype, which increases the usefulness of its use on sandy and sandy sandy soils suffering from the lack of these components.

The presence of calcium and a high content of magnesium are especially effective in influencing the yield of such agricultural crops as barley, oats, sunflower, corn, clover, winter rye.

Example. 62.8 ma.ch. crushed waste electrolyte containing,%: potassium chloride 75; magnesium chloride 7.5; magnesium oxide 0.5} calcium chloride 1; water 1; sodium chloride and others. The rest is mixed from May 12, h. crushed carnallite chlorine sludge containing,%: potassium chloride 30-, magnesium chloride 33; magnesium oxide 30j calcium chloride 0.3; water 1} sodium chloride and others. The rest, and 1 ma.ch. sublimates from chlorine lines containing,%: potassium chloride 40j magnesium chloride 30-, sodium chloride 28; water 2. The resulting mixture is moistened with stirring 24.2 wt.h. gas cleaning effluent containing, g / l: calcium chloride 150; magnesium chloride 30; potassium chloride 25; sodium chloride 8. The resulting mass has a moisture content of 19.6%.

The wet mixture is granulated by extrusion, pushing it through holes of 4 mm in diameter, and loaded into the fluidized bed of granules. The temperature in the 250 С layer is the heat carrier velocity of 6 nm / s. The dried granules are cooled with air in a fluidized bed at the same air velocity. The particles removed from the layer are returned to mixing with the starting materials. The resulting finished product - mineral fertilizer Kalimag chloride - contains,%: potassium chloride 62.4; magnesium chloride 11.7, calcium chloride 5.2 $ magnesium oxide 5.0; sodium chloride 12.8; water 2.9. The content of magnesium compounds in terms of chloride is 23.5%. The dynamic strength of granules is 95%, the yield of granulated fertilizer is 92%.

The effect of the claimed process parameters on the quality of the fertilizer produced is presented in the table.

From the data of the table it follows that the use of the proposed method of obtaining granulated fertilizer allows to increase the dynamic strength of the granules to 90 percent or more against the 80% required by GOST 21560.30 76, which leads to an increase in its shelf life from 0.5 to 1.5 years, reduces the abrasion of granules during transportation and, accordingly, the cost of preparing and applying fertilizers to

5 soil.

The results of agrochemical tests showed that potassium chloride enriched with calcium and magnesium compared with granulated potassium chloride

Q electrolyte increases the yield of potatoes, cabbage, fodder beet, silage crops of mixed crops by an average of 5-10%, at the same time increasing the content of sodium and magnesium in them and improving the mineral composition of forage crops with a more favorable ratio K: (Ca + + Na + Mg).

The advantage of the proposed method is also the involvement in the production of fertilizers previously Hencnonbsveh magnesium production waste (gas cleaning, dust, sublimates) while reducing the degree of contamination

from the environment.

Claims (4)

1. A method of producing Kalimagnium Q fertilizer by treating magnesium and chlorine salt production wastes by electrolysis of a melt dehydrated in salt-tapping furnaces or carnallite chlorinators, comprising mixing ground electrolyte melted after electrolysis with slag carnallite chlorinators or salt-tapping furnaces when the mixture is moistened, granulation of the mixture, thermob5 0 processing and cooling of the finished product, characterized in that, in order to improve the quality of the fertilizer and increase its storage time, or with a decrease in the degree of pollution of the environment, sublimates and dust generated during the dewatering and electrolysis stages of carnallite are additionally mixed, and The uv-jq calcination is carried out with calcium-containing chloride effluents of gas scrubbers at these stages until the mixture reaches 13-20% of moisture, while the heat treatment and cooling is granulated 5} of the material is carried out in a fluidized bed with a return etura the mixing step. 2. The method according to claim 1, characterized in that the mixing of salt 20 The humidity of the mixture, wt.% The temperature in the layer, ° C Gas velocity in the layer, nm / s Chemical composition of granulated fertilizer, May.%: KC1 MgCl MgO. SAS1g NaCl Н20 MgCl2 + MgO in in terms of MgCla Dynamic strength of granules (GOST 215603-76) The output of granulated fertilizer,% Plant capacity,% Specific fuel consumption,% 2419.6 18.1 16.5 14.7 12.9 10 300 250 225 200175150 150 6.5 4.5 one 0.7 Waste from the production of magnesium and chlorine is carried out until the amount of magnesium in terms of magnesium chloride, in terms of magnesium chloride, is 10-25%. 3. The method according to claim 1, characterized by the fact that calcium-containing gas scrubbers in the amount of calcium chloride in the finished fertilizer in the range of 0.5-5% is fed to the mixing of the salt waste. 4. A method according to claim 1, characterized in that the heat treatment of the granulated mixture. In the fluidized bed is carried out at a temperature of 150-250 ° C and the speed of the coolant 1-6 nm / s. 4.5 one 0.7