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CN-122010158-A - Low-grade fluorite sulfuric acid purification method for solving problem of calcium sulfate wrapping

CN122010158ACN 122010158 ACN122010158 ACN 122010158ACN-122010158-A

Abstract

The invention belongs to the technical field of mineral processing, and particularly relates to a low-grade fluorite sulfuric acid purification method for solving the problem of calcium sulfate wrapping. The method mainly comprises the steps of raw material pretreatment, segmented acid leaching reaction and post-treatment. The sectional acid leaching reaction process adopts the steps of adding the total acid amount in batches in the dilute sulfuric acid leaching process, and applying high-strength mechanical stirring and/or ultrasonic treatment between batches and in the reaction process, so that the calcium sulfate coating can be effectively destroyed and stripped, and continuous and full contact between acid liquor and impurities (mainly calcite and silicon dioxide) is ensured. The method is simple and low in cost, can obviously improve the grade and recovery rate of fluorite concentrate, and is easy for industrial application.

Inventors

  • YANG HUACHUN
  • YU HEHUA
  • YAN CHUNSHENG
  • ZHAO LINXIA
  • YANG SHUIYAN
  • LI CHEN
  • LIU SIYUAN
  • LI XIAOQIANG
  • ZHAI SUHUI

Assignees

  • 河南省氟基新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260226

Claims (10)

  1. 1. The low-grade fluorite sulfuric acid purification method for solving the problem of calcium sulfate encapsulation is characterized by comprising the following steps: S1, raw material pretreatment, namely crushing and grinding low-grade fluorite raw ores, and then carrying out magnetic separation to remove iron to obtain pretreated fluorite powder; s2, sectional acid leaching reaction, namely adding dilute sulfuric acid with the mass concentration of 5-15 wt% into the pretreated fluorite powder in the step S1 in a sectional manner according to a proportion, and obtaining a solid-liquid mixture after the sectional acid leaching reaction is completed, wherein the mass ratio of the total consumption of the dilute sulfuric acid to the pretreated fluorite powder is 0.8-1.2:1; And S3, post-treatment, namely separating the solid-liquid mixture in the step S2 by gravity to obtain an underflow, and carrying out filter pressing, washing and drying on the underflow to obtain fluorite concentrate.
  2. 2. The method for purifying low-grade fluorite sulfuric acid for solving the problem of calcium sulfate encapsulation according to claim 1, wherein the low-grade fluorite raw ore in S1 comprises 85-88wt% of CaF 2 , 0.8-0.9wt% of SiO 2 , 0.8-0.9wt% of CaCO 3 , 1.4-1.5wt% of Fe 2 O 3 and the balance of other impurities.
  3. 3. The method for purifying low-grade fluorite sulfuric acid for solving the problem of calcium sulfate encapsulation according to claim 1, wherein the low-grade fluorite raw ore in S1 is crushed and ground to obtain fluorite powder with a particle size of 200 meshes or less.
  4. 4. The method for purifying low-grade fluorite sulfuric acid for solving the problem of calcium sulfate encapsulation according to claim 1, wherein the step of the segmented acid leaching reaction in S2 is divided into 2-3 segments, and the reaction conditions of each segment of acid leaching reaction are that stirring is carried out for 10-50 minutes at a stirring speed of 300-1000 rpm and a temperature of 20-60 ℃.
  5. 5. The method for purifying low-grade fluorite sulfuric acid for solving the problem of calcium sulfate encapsulation according to claim 4, wherein the reaction conditions of each stage of acid leaching reaction are the same or different, and the reaction conditions include stirring at a stirring rate of 300-800 rpm for 10-30 minutes at 20-60 ℃ or stirring at a stirring rate of 400-1000 rpm for 20-50 minutes at 20-60 ℃.
  6. 6. The method for purifying fluorite sulfuric acid with low grade for solving the problem of calcium sulfate encapsulation according to claim 4, wherein when the sectional acid leaching reaction is divided into 2 sections, the amount of the dilute sulfuric acid in the first section is 40-60wt% of the total amount of the dilute sulfuric acid, the rest of the dilute sulfuric acid is used in the second section, and when the sectional acid leaching reaction is divided into 3 sections, the amount of the dilute sulfuric acid in the first section is 30-40wt% of the total amount of the dilute sulfuric acid, the amount of the dilute sulfuric acid in the second section is 30-40wt% of the total amount of the dilute sulfuric acid, and the rest of the dilute sulfuric acid is used in the third section.
  7. 7. The method for purifying fluorite sulfuric acid in low grade for solving the problem of calcium sulfate coating according to claim 4, wherein intermittent ultrasonic treatment is applied during at least one stage of acid leaching reaction or between two adjacent stages of acid leaching reactions.
  8. 8. The method for purifying low-grade fluorite sulfuric acid for solving the problem of calcium sulfate encapsulation according to claim 7, wherein the intermittent ultrasonic treatment has a frequency of 20-40 kHz and a power of 100-500W, and adopts a mode of working for 1-5 minutes and intermittently for 5-15 minutes.
  9. 9. The method for purifying low-grade fluorite sulfuric acid for solving the problem of calcium sulfate encapsulation according to claim 1, wherein the washing liquid adopted in the step S3 comprises water, the washing liquid is neutral, and the drying temperature is 100-110 ℃.
  10. 10. A fluorite concentrate obtained by the low-grade fluorite sulfuric acid purification method for solving the problem of calcium sulfate wrapping according to any one of claims 1 to 9.

Description

Low-grade fluorite sulfuric acid purification method for solving problem of calcium sulfate wrapping Technical Field The invention belongs to the technical field of mineral processing, and particularly relates to a low-grade fluorite sulfuric acid purification method for solving the problem of calcium sulfate wrapping. Background Fluorite (CaF 2) is an important strategic mineral resource. With the exhaustion of high-grade fluorite ore, efficient use of low-grade fluorite has become a research hotspot. The low-grade fluorite generally contains gangue minerals such as calcite (CaCO 3) and quartz (SiO 2). Acid leaching is a common purification method, wherein dilute sulfuric acid is of great interest because of its low cost and wide source. However, a major technical hurdle in dilute sulfuric acid treatment is that the calcium sulfate (CaSO 4•2H2 O, gypsum) produced by the reaction of sulfuric acid with calcite has a very low solubility in water (about 0.21g/100mL at ambient temperature). In the reaction process, gypsum can rapidly crystallize on the surfaces of fluorite particles and form a layer of compact wrapping film, so that the continuous diffusion of sulfuric acid into the particles and the reaction of residual calcite and other impurities are seriously hindered, the impurity removal efficiency is rapidly reduced, and the purity of the product is difficult to further improve (the grade of CaF 2 is difficult to stably break through more than 90 percent of bottleneck generally). The prior art has the problems of cost, environmental protection or equipment corrosion due to the adoption of mixed acid (such as sulfuric acid-hydrochloric acid) with higher cost or the use of hydrofluoric acid with strong irritation. In order to avoid the problem, the prior art adopts the following schemes that 1) acid with higher solubility of calcium salt such as hydrochloric acid, nitric acid and the like is used, but the cost is obviously increased (patent document CN 105967190A), 2) strong fluoride such as hydrofluoric acid or fluosilicic acid and the like is used, siO 2 can be synchronously removed, but the risk of extremely toxicity, strong corrosiveness and environmental pollution exists (patent document CN 108439452A), and 3) the formed compact coating layer cannot be fundamentally destroyed simply by conventional optimization means such as improving the reaction temperature, prolonging the reaction time or enhancing the stirring, and the effect is limited and the energy consumption is increased (patent document CN 101913641A). Therefore, a novel method capable of effectively solving the problem of calcium sulfate wrapping, fully playing the cost advantage of dilute sulfuric acid and remarkably improving the low-grade fluorite purification efficiency is developed, and the method has important industrial application value. Disclosure of Invention Based on the method, the invention aims to provide a low-grade fluorite sulfuric acid purification method for solving the problem of calcium sulfate wrapping, and the method can effectively break a calcium sulfate wrapping layer and remarkably improve fluorite grade and recovery rate. In order to achieve the above purpose, the present invention adopts the following technical scheme: The invention provides a low-grade fluorite sulfuric acid purification method for solving the problem of calcium sulfate wrapping, which comprises the following steps: S1, raw material pretreatment, namely crushing and grinding low-grade fluorite raw ores, and then carrying out magnetic separation to remove iron to obtain pretreated fluorite powder; s2, sectional acid leaching reaction, namely adding dilute sulfuric acid with the mass concentration of 5-15 wt% into the pretreated fluorite powder in the step S1 in a sectional manner according to a proportion, and obtaining a solid-liquid mixture after the sectional acid leaching reaction is completed, wherein the mass ratio of the total consumption of the dilute sulfuric acid to the pretreated fluorite powder is 0.8-1.2:1; And S3, post-treatment, namely separating the solid-liquid mixture in the step S2 by gravity to obtain an underflow, and performing filter pressing, washing and drying on the underflow to obtain fluorite concentrate, wherein the gravity separation preferably comprises the steps of separating the solid-liquid mixture by a hydraulic separator, and collecting the underflow for later use. Further, the low-grade fluorite raw ore in S1 comprises 85-88wt% of CaF 2, 0.8-0.9wt% of SiO 2, 0.8-0.9wt% of CaCO 3, 1.4-1.5wt% of Fe 2O3 and the balance of other impurities. Further, the low-grade fluorite raw ore in S1 is crushed and ground to obtain fluorite powder with a particle size of 200 meshes or less. Further, the segmented acid leaching reaction in the step S2 is divided into 2-3 segments, and the reaction conditions of the acid leaching reaction in each segment are that stirring is carried out for 10-50 minutes at 20-60 ℃ at the stirrin