RU2232130C2 - Method of producing crystalline calcium chloride from cyclone dust of potassium ore flotation concentrate - Google Patents

Abstract

FIELD: mining industry.

SUBSTANCE: invention relates to technology of processing sylvinite ores into potassium fertilizers and aims at producing white calcium chloride from cyclone dust ore flotation concentrate. The latter process comprises dissolution of cyclone dust, clarification of solution using polyacrylamide coagulant-assisted separation of clay sludge, and crystallization of calcium chloride from clarified solution. Dissolution of cyclone dust is effected in presence of modifying reagent selected from polyethylene glycol alkyphenyl ethers, in particular OP-10, OP-7, Neonol AF 9-12, and AF 9-14 consumed in amounts 2.5 to 10.0 g per 1 t cyclone dust.

EFFECT: improved technology and suppressed negative effect of residual flotation reagents.

2 cl, 2 tbl

Description

The invention relates to a technology for processing sylvinite ores into potash fertilizers and is intended for the production of white potassium chloride from cyclone dust from a flotation concentrate.

The cyclone dust obtained by drying the flotation concentrate is its substandard part, as it has a low quality due to the low content of potassium chloride and finely divided composition, and therefore is not suitable for sale as a commercial product. A significant amount of clay sludge is contained in cyclone dust, as well as residual flotation reagents (aliphatic amines, technical flotamine, OFA, oxal, etc.) used in the flotation method of processing sylvinite (potassium) ore.

A known method of producing potassium chloride, in which a small fraction of the crushed potassium ore is first treated with a flocculant, concentrated and floated, and then hydromechanically de-slamming and flotation again (USSR Author's Certificate No. 1527230, class 05 D 1/04 of 08/11/1987 )

The disadvantages of this method are the complex technological scheme, the high consumption of reagents, the relatively low extraction of KC1 from the fine fraction into the product.

There is another method for producing potassium chloride from potash ore, including its grinding, desliming, flotation, dehydration and drying of the concentrate, where a small fraction is extracted from the main sylvin flotation feed, deslimed together with the crushed ore and returned to the flotation (patent No. 2057102).

The main disadvantage of this method is the return of the fine fraction of flotation concentrate into the process and its accumulation in the system. As a result, the fine fraction together with the potassium chloride flotation concentrate enters the dryer, forming a large amount of cyclone dust with a finely divided composition. This dust is usually sent for additional processing by granulation, which is a costly, energy-intensive and inefficient process.

The closest in technical essence to the claimed technical solution is a method for producing potassium chloride from cyclone dust of a flotation concentrate, which includes dissolving cyclone dust, clarifying a solution from clay mud with the introduction of a polyacrylamide coagulant and crystallizing potassium chloride from a clarified solution (Popova T.M., Yurkina M .I. Analysis of technological schemes for processing dust fractions of flotation concentrate. "Prospects for the use of new types of raw materials in the production of potash fertilizers". L .: 1980, p. 13-20).

Production tests and the practice of experimental industrial use at JSC Uralkali showed the unsuitability of this method of processing cyclone dust to produce white potassium chloride that meets the requirements of GOST 4568-95 and the conditions of supply to foreign consumers. This is due to the fact that upon dissolution of cyclone dust and after clarification from an insoluble residue, the solution is intensely colored in brown due to the presence of a stable colloidal suspension of clay mud, which does not settle for 24 hours and even longer. During crystallization, finely crystalline potassium chloride with an intense pink color is released from such a solution. The dyed product is considered non-standard and is usually not accepted by foreign consumers of potash fertilizers.

To eliminate these drawbacks, an effective technology for cleaning the solution of cyclone dust from colloidal suspension of clay sludge and suppressing the negative effect of residual flotation reagents is required.

To solve this problem, it is proposed to dissolve cyclone dust, clarify the solution from clay mud with the introduction of a polyacrylamide coagulant and crystallize potassium chloride from the clarified solution. Dissolution of cyclone dust is carried out in the presence of a modifying reagent from the class of alkylphenyl ethers of polyethylene glycol: OP-10, OP-7 or Neonol AF9-12, AF9-14 with a specific consumption of 2.5-10.0 g per ton of dissolving cyclone dust.

When the specific consumption of the modifying reagent is less than 2.5 g per ton of dust, the positive effect sharply decreases, and an increase in the consumption of the reagent over 10.0 g per ton of dust does not lead to a further increase in its effectiveness, but financial costs increase.

The inventive method with the introduction of the modifying reagent into the process of dissolution of cyclone dust flotation concentrate provides:

- high-quality cleaning of the solution from clay sludge when it is clarified by settling;

- obtaining white potassium chloride during crystallization from a clarified solution of cyclone dust;

- improving the particle size distribution of the obtained KCl crystals;

- achieving a high positive effect with low additional costs;

- increasing the completeness of the extraction of potassium chloride in a commercial product during flotation concentration of sylvinite ore in potassium fertilizer.

The proposed method for producing potassium chloride from cyclone dust of a flotation concentrate was tested during laboratory studies and passed production tests at Uralkali.

Example:

Cyclone dust trapped during drying of flotation potassium chloride is dissolved in two horizontal apparatuses with stirring devices, an aqueous solution heated to a predetermined temperature, which comes from scrubbers for wet cleaning of flue gases of dryers. In the first solvent, together with a scrubber solution, a 0.1% solution of modifier reagent is dosed with the recommended flow rate. A suspension of cyclone dust, containing a solution of potassium chloride and an insoluble clay sludge residue and intensely colored in brown, is continuously withdrawn from the second solvent into a receiving container. Then, the suspension is pumped through a surface heater into a two-section conical sump, into which a 0.1% solution of polyacrylamide coagulant is introduced at a rate of (12-15) g PAA per ton of dissolved cyclone dust. Clarified from clay sludge and a bleached solution from the sump is passed through a buffer tank to the main production of halurgic potassium chloride, where a crystallization process is carried out by vacuum-cooling the solution. The separated KC1 crystals are separated from the mother liquor, dried, and a white marketable product is obtained, which is shipped to consumers.

The results of laboratory testing of the method are shown in table 1.

The results of production testing of the method are given in table. 2.

Claims (2)

1. A method of producing crystalline potassium chloride from cyclone dust of potassium ore flotation concentrate, comprising dissolving cyclone dust, clarifying a solution from a clay slurry with the introduction of a polyacrylamide coagulant, and crystallizing potassium chloride from a clarified solution, characterized in that the cyclone dust is dissolved in the presence of a modifier reagent from class of alkylphenyl ethers of polyethylene glycol. 2. The method according to claim 1, characterized in that the OP-10, OP-7 or Neonol AF 9-12, AF 9-14 with a specific consumption of 2.5-10.0 g per tonne of solubility are used as a modifying reagent cyclone dust.