RU2078040C1 - Method for production of concentrated carnallite - Google Patents

Abstract

FIELD: ore dressing. SUBSTANCE: ore is disintegrated and separated into mineral constituents to isolate via vacuum crystallization concentrated carnallite as final product. Method also includes countercurrent washing of dissolution clay-sludge waste and combined filtration of halite-sludge production waste. Process is conducted in two steps. In the first step, isolation of 75-90% halite from ore by floatation into foam product is performed, and then carnallite is subjected to complete hot dissolution from dehydrated chamber floatation product to yield clarified solution saturated at 95-100 C with magnesium, potassium and sodium chlorides. Carnallite is isolated from this solution using vacuum crystallization procedure. EFFECT: enhanced efficiency of process. 4 cl, 1 dwg, 1 tbl

Description

 The invention relates to a technology for the production of enriched carnallite and can be used to increase the efficiency of processing carnallite ores or other types of mining chemical carnallite-containing raw materials.

The production of enriched carnallite raw materials for the production of magnesium metal and various types of magnesium-containing fertilizers is currently carried out in Russia from carnallite ores, which are mainly carnallite -KCl-MgCl ₂ -6H ₂ O (60-80%), halite -NaCl (18- 38%) and small amounts of CaSO ₄ anhydride, sylvin and water-insoluble clay minerals.

The technology used provides for underground mining of ore, grinding it to a particle size of 5 mm, leaching of carnallite from ore at a temperature of 95-100 ^o C, clarification of the liquors obtained, enriched carnallite vacuum crystallization from them, its dehydration in centrifuges to a free moisture content of 3% halite filtration the remainder, countercurrent washing of the clay-sludge product with its subsequent storage in the sludge dump (USSR copyright certificate 278654, class C 05 F 5/30, 1970).

The disadvantage of this method is the high heat consumption (200 Mgcal / t) and the need for expensive equipment manufactured using titanium or special steels that ensure long-term operation of the equipment in highly concentrated magnesium-containing liquors at a temperature of 95-100 ^o C
A combined method for processing carnallite ores is known, which involves leaching magnesium chloride from the ore in the first stage, followed by controlling the brine and vacuum crystallization of carnallite, separating insoluble residue by filtration, and using the flotation method in the second stage to extract potassium chloride sylvin (ed. St. USSR N 1261905, C 01 F 5/30 from 11.20.84, publ. 07.10.86).

 The purpose of the invention is the complex processing of ore to produce carnallite and potassium chloride, the disadvantage of this method is the high heat consumption for evaporation of solutions.

 A known method for the combined processing of carnallite-containing ores, when after dissolving in the first stage of the process, sodium chloride is evolved by vacuum crystallization, then the remaining solution is evaporated to separate cainite, then the solution is again evaporated and carnallite is crystallized (auth. St. N 1122612, C 01 D 3/04 dated 03.22.82, publ. 07.11.84). The method is used to obtain carnallite from polymineral magnesium-containing ores, but it requires large heat costs for multiple evaporation of the resulting solutions.

The proposed method provides for the preparation of enriched carnallite from carnallite ore according to a combined scheme, which, after grinding the ore, provides the process in two main stages:
at the first stage, flotation separation of 75-90% halite from ore by flotation to a foam product;
in the second stage, complete hot dissolution of carnallite from the dehydrated chamber flotation product to obtain a clarified solution saturated at a temperature of 95-100 ^o C on magnesium, potassium and sodium chlorides, and subsequent vacuum crystallization of carnallite from it.

 For the prototype, dissolution of carnallite is carried out in two expensive screw solvents located in series with elevator discharge of solid phase from them, the third similar solvent with elevator discharge of sediment is used to recover the heat of halite waste before filtering it. According to the proposed method, in connection with the preliminary flotation of halite and the complete dissolution of carnallite, there is no need to filter the solid residue from dissolution and the dissolution of carnallite itself is carried out in simple mechanical mixers.

 A small amount of insoluble residue is subjected to countercurrent washing, all halite-sludge waste is dehydrated together and stored (see drawing).

 The allocation of 75-90% halite at normal temperature reduces the heat cost of obtaining enriched carnallite by 15-20%. With a smaller amount of halite released by the flotation method, there is no noticeable decrease in heat consumption, while the amount of clay-salt insoluble residue in the dissolution cycle increases and the necessary the area of thickeners for clarification of liquors and countercurrent washing of sludge, and consequently, the cost of production.

 When the degree of halite extraction by flotation is more than 90%, the losses of magnesium chloride with gallite product significantly increase. At the same time, production costs increase due to increased reagent costs.

The flotation chamber product is dehydrated to a liquid phase content of 5-25 wt. When the liquid phase content is more than 25%, the ratio of the amount of potassium chloride to the amount of magnesium chloride in the dehydrated chamber flotation product (KCl: MgCl ₂ ) becomes less than 0.72. In this case, in a saturated saline solution after dissolution of carnallite, an insufficient amount of potassium chloride is observed to completely crystallize magnesium chloride in the form of carnallite, which leads to a decrease in the extraction of magnesium chloride in the finished product and lower yield of the finished product.

 When the content of the liquid phase in the dehydrated chamber flotation product is less than 5%, the required dehydration time sharply increases, and therefore, large capital and operating costs for dewatering equipment are required.

 Hot dissolution is carried out for 5-15 minutes, which is significantly less than the prototype. At a dissolution time of less than 5 minutes, complete dissolution of magnesium chloride is not achieved; at a dissolution time of more than 15 minutes, heat and operating costs increase, without leading to an improvement in the process performance.

 Feeding the filtrate after dehydration of halitic-sludge production waste to countercurrent washing of sludge from the dissolution process allows, under the combined flotochemical scheme of carnallite processing, on the one hand, to increase the yield of magnesium chloride in the finished product in the dissolution-crystallization department, and, on the other hand, to improve the water balance in the flotation unit.

Conducting countercurrent washing without supplying a filtrate to it after dehydration of halite-sludge production waste leads to:
to the formation of excess water in the flotation cycle and to additional losses of magnesium chloride due to the need to discharge excess chlorine-magnesium liquors;
to reduce the extraction of magnesium chloride by 0.5% in the Department of dissolution-crystallization by replacing the wash water with fresh water.

 The proposed method for producing enriched carnallite in comparison with the prototype was tested under experimental conditions at a facility represented by a flotation machine for halite flotation, filters for dewatering halite-slurry and chamber flotation products, a unit for hot dissolution of carnallite, a crystallizer for separating carnallite, a mixer for countercurrent washing of slurry product .

The tests were carried out on the carnallite ore of the Solikamsk deposit (Silvinit JSC) of the following composition, carnallite 64.55% halite 28.36; sylvin 5.33; anhydrite 0.71; clay water insoluble residue 1.05; the content of magnesium chloride 23.3%
Example 1 (prototype). The ore was hot leached at a temperature of 97 ^o C, the resulting saturated liquor was clarified and sent to vacuum crystallization to highlight carnallite.

 Halite waste was filtered, the sludge product was subjected to countercurrent washing of the sludge with the introduction of fresh water.

 Example 2 (the proposed method). Flotation of halite from ore was carried out at different flow rates of reagent-collector-alkylmorpholine. The flotation chamber product was dehydrated to a liquid phase content of 20%, then hot dissolution was carried out for 10 min to obtain a clarified saturated solution and vacuum crystallization of carnallite from it.

 The halitic foam flotation product was filtered together with the washed sludge dissolution product.

 A small amount of insoluble halite-sludge product was subjected to countercurrent washing with the addition of a filtrate from dehydration of halite-sludge waste.

 Example 3 (the proposed method). Flotation was carried out with the extraction of 90% halite, the chamber flotation product was dehydrated to various contents of the liquid phase, then carnallite was dissolved and further operations were performed in accordance with the conditions of Example 2.

 Example 4 (the proposed method). Flotation was carried out with halite extraction. 70% chamber flotation product was dehydrated to a liquid phase content of 20%, the dissolution time was 3-17 minutes. Other conditions of the example are similar to the conditions of example 2.

 Example 5 (the proposed method). Halite extraction in the flotation cycle 80% liquid phase content in the dehydrated flotation chamber product 20% dissolution time 10 min, the rest of the conditions are similar to examples 2.

 Countercurrent washing of the sludge product was carried out with and without supply of the filtrate after filtering halite-sludge waste.

 The test results are presented in the table.

 The proposed technology has passed pilot industrial tests and is accepted for industrial use at Silvinit JSC. The economic effect of the implementation of combined flotochemical technology at Silvinit JSC will be 300 million rubles / year.

 The proposed technology can be applied at carnallite factories processing carnallite ores or carnallite-containing raw materials.

Claims (3)

 1. A method of producing enriched carnallite from carnallite-containing ores, comprising grinding the ore, separating it into mineral components with vacuum crystallization as a finished product of enriched carnallite, countercurrent washing of clay-sludge dissolution waste, co-filtration of halite-sludge production waste to form a filtrate, characterized in that the process is carried out in two stages, providing for the first stage, the separation of 75 90% halite by flotation in foam odukt, and in the second stage hot complete dissolution of carnallite formed in the first stage chamber flotation product with subsequent vacuum-crystallization of carnallite from the clarified liquor. 2. The method according to p. 1, characterized in that before dissolving the chamber flotation product is dehydrated to a liquid phase content of 5 25%
3. The method according to claim 1, characterized in that the dissolution is carried out for 5 to 15 minutes  4. The method according to p. 1, characterized in that the countercurrent washing of clay-slag waste is carried out with the addition of a filtrate formed from the filtration of halite-sludge production waste.

Images