Process for preparing potassium magnesium sulfate fertilizer with two-stage conversion and floatation method

Abstract

The invention relates to a process for producing a potash magnesium sulphate fertilizer through secondary conversion and flotation method, comprising the following steps of: raw ore crushing, primary conversion, filtration, secondary conversion, mixture making, floatation, filtration, drying and packaging. The process adopts secondary conversion to make potassium-bearing mineral in potash-magnesia mixed salt completely convert into schoenite at a normal temperature, which avoids potassium element from losing in ore tailing because of incomplete conversion; secondary mother liquor is recycled so as to reduce the loss of the potassium element in discharged tail washings, thereby greatly improving recovery rate of the potassium element; and the process has the advantages of short process flow, energy conservation and simple operation, etc.

Description

1. Technical field [0001] The invention belongs to the field of salt chemical industry, and in particular relates to a process for producing potassium magnesium sulfate fertilizer by two-stage conversion and flotation. 2. Technical background [0002] Potassium magnesium sulfate fertilizer, the mineralogy name is langbeinite, molecular formula: K 2 SO 4 MgSO 4 6H 2 O, because it contains potassium, magnesium, and sulfur, which are essential elements for crop growth, can significantly increase crop yield, enhance crop cold resistance, drought resistance, and insect resistance, and is known as the "golden partner" of crop fertilization. Since it contains three nutrients of potassium, magnesium and sulfur, it can be used as a fertilizer and applied to economic crops, such as tobacco, vegetables, fruit trees, tea, etc. The countries producing potassium and magnesium sulfate fertilizer at home and abroad mainly include the United States, Russia and China. There are three prod...

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Problems solved by technology

The first method is suitable for use in mines of langbeinite ore. Most of the sulfate-type potassium-containing brines in China are difficult to produce langbeinite ore and cannot be used; the second method uses mechanical desodination technology to produce potassium magnesium sulfate fertilizer. Since the first-stage conversion of this method is completed under heating, it has the disadvantage of high energy consumption; the third method has the advantage of short flow process, but also has defects. It is necessary to add a large amount of water to the potassium-magnesium mixed salt during the first-stage conversion. The potassium-containing minerals are decomposed into langbeinite, so the formed mother liquor is langbeinite saturated solution, in which the potassium content is high (greater than 30g / l), the tailings potassium grade is high (greater than 2%), and the recovery rate of the operation is low Defects

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