In-situ roasting and mining method of polyhalite

Abstract

The invention provides an in-situ roasting and mining method for polyhalite. The in-situ roasting and mining method comprises the steps that water injection wells which take a roasting well as the center and are distributed in a regular polygon state are arranged for well drilling; and oxygen-enriched air is injected into the roasting well, ignition is conducted, water is injected into the roasting well, high-temperature hot leaching starts to be conducted, and potassium ion leaching mining is conducted. In-situ roasting of polyhalite is achieved through large-caliber underground fuel fillingand gas injection combustion, waste heat generated in the roasting operation process is used for heating surface water, and hot water leaching is achieved. A polyhalite crystal structure is destroyedby the roasting method, the potassium resource dissolving efficiency can be greatly improved after water is injected, the potassium recovery rate is further improved, the water consumption of unit polyhalite leaching is reduced, in addition, as a region generally influenced by roasting can be preferentially leached, the leaching range can be better controlled, and the method has the advantages ofsimplicity, feasibility, and low production cost.

Description

technical field [0001] The invention belongs to the technical field of potassium salt extraction, and in particular relates to an in-situ roasting mining method for polyhalite. Background technique [0002] my country is a large agricultural country. Potassium is one of the three important elements for crop growth. Currently, it is facing a large-scale shortage of potassium in cultivated land. Potassium fertilizer is the key fertilizer for agricultural production. The shortage of potassium fertilizer resources restricts the development of my country's agriculture. The main source of potassium It is soluble potassium, but my country's soluble potassium resources are seriously lacking, and it is difficult to find ore for soluble potassium salts. For many years, my country's potassium fertilizer production cannot meet domestic demand. [0003] Potassium salts are mainly divided into two types according to the mode of occurrence and phase state: liquid potassium salts and solid p...

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Problems solved by technology

The relevant methods published so far include "a mining method for polyhalite, 201710791658.2", "a process for producing potassium sulfate by leaching mother liquor with polyhalite, 201610045396.0", "extracting potassium by static leaching from polyhalite ore and Method for preparing potassium sulfate, 201310320200.0", "A method for in-situ reaction of deep polyhalite ore to produce water-soluble potassium salt, 201310310354.1", "Method for leaching potassium in polyhalite ore, 200510021637.X" etc., but limited by the poor solubility of polyhalite, its extraction process is often difficult, and the leaching method is generally used for mining, but the leaching effect of most leaching agents is often not ideal

[0004] With the deepening of research, the "roasting-hot soaking" potassium dissolving method of polyhalite shows extremely high dissolution efficiency (Cheng Huaide, 2019, "Inorganic Salt Industry"). The loss of structural water causes structural damage, followed by hot water leaching, and the leaching recovery rate of potassium reaches more than 95%, which is more than 3 times higher than the potassium recovery rate obtained by conventional hot water leaching and normal temperature leaching, but the existing The technical leaching effect is limited, and the average recovery rate of potassium resources in polyhalite is only about 30%. Applicable; third, in the prior art, due to the low density of the injected leaching agent during the leaching process, the leaching direction is often upward, and the leaching effect of the lower part is poor

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