Process for leaching dissoluble potassium from polyhalite

Abstract

The invention discloses a process for leaching dissoluble potassium from polyhalite. The process comprises the following steps of firstly, grinding ores: crushing polyhalite ores, and grinding the ores to be smaller than or equal to 80 meshes to obtain an ore ground product; secondly, roasting: roasting the ore ground product at the temperature of 350 to 500DEG C for 20 to 90 minutes to obtain a roasted product; thirdly, performing acid leaching: adding an acid solution into the roasted product according to the sold-liquid ratio of 1:0.8 to 10, and leaching at the temperature of 25 to 100DEG C for 20 to 120 minutes to obtain a polyhalite ore pulp; and fourthly, performing solid-liquid separation: performing solid-liquid separation on the polyhalite ore pulp to obtain a dissoluble potassium solution. The K<+> concentration in the obtained dissoluble potassium can reach as high as 8.10 weight percent; the dissoluble potassium solution can be repeatedly leached, so that the evaporation and concentration cost at later stage is reduced; the leaching rate of potassium can reach as high as 95.5 percent, and the leaching cycle is only 1 to 2 hours. The process disclosed by the invention is simple; raw materials of the leaching solution are wide in source and are low in cost; an obtained acid leaching mother solution can be recycled.

Description

technical field [0001] The invention relates to a process for leaching potassium-containing minerals, in particular to a process for leaching soluble potassium from insoluble polyhalite. Background technique [0002] Polyhalite (K 2 SO 4 · MgSO 4 2CaSO 4 2H 2 O) is a kind of insoluble potassium ore widely distributed in sulfate-type sylvite deposits, and its theoretical potassium content (K 2 SO 4 ) up to 28.9%, which is an important potash resource. It has been found that there are abundant polyhalite deposits in the deep part of the marine sedimentary basins in Sichuan, Hubei, Jiangsu, Shandong, Shanxi, Qinghai and other provinces. Among them, Sichuan and Hubei have the largest amount of ore, and only (four) eastern (eastern) Sichuan polyhalite resources are equivalent to K 2 The reserves of O are more than 20 billion tons, and it has become an important raw material for my country's potash fertilizer industry. Since my country is a large agricultural country with...

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Problems solved by technology

For example, CN103930371A discloses a method for processing polyhalite ore to produce potassium sulfate by calcination and hydrolysis. The polyhalite ore is decomposed by calcination and then leached to extract potassium sulfate in an aqueous medium, which can greatly increase the leaching speed, about 30 minutes or more The residence time can achieve a leaching rate of about 90%, but due to the limited solubility of potassium sulfate, there are still disadvantages such as a large amount of leaching medium, a dilute concentration of the leaching mother liquor, and high energy consumption in the subsequent evaporation process; Li Chunge et al. disclosed the production of polyhalite Potassium sulfate process research, examined the different leaching agents and solid-liquid ratios on the K in polyhalite + The influence of the leaching rate, the results show that: when CaO is used as the leaching agent, the reaction temperature is 70 ° C, and the solid-liquid ratio is 1:4, K + The leaching rate is 78.8%. When water is used as the leaching agent, the reaction temperature is 70°C, and the solid-to-liquid ratio is 1:6, K + The leaching rate is only 73.0%, and the leach solution K + The concentration is generally maintained at 2.0-3.0wt%. However, the leaching rate of this process is low, and the concentration of the leachate is low, which increases the energy consumption of evaporation and crystallization in the later stage (Li Chunge et al. Research on the process of producing potassium sulfate from polyhalite. Chemical Minerals and Processing, 2013 No. 7 period); CN104878197A discloses a method for leaching potassium under atmospheric pressure and low temperature assisted by ultrasonic waves, which also adopts the mixed leaching process of acid and ore, but the mineral targeted is potassium feldspar, which is completely different from polyhalite mineral properties, and the required The reaction conditions are very harsh and cannot solve the key technical problems of leaching soluble potassium from polyhalite ore