Method for producing hydrofluoric acid from fluorite as raw material

A technology of hydrofluoric acid and raw materials, applied in the direction of fluorine/hydrogen fluoride, etc., can solve the problems of hindering the reaction, high sulfuric acid concentration, unable to complex calcium, etc., and achieve the effect of reducing leaching cost, simple leaching equipment, and convenient operation.

Inactive Publication Date: 2012-07-11
CENT SOUTH UNIV
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  • Abstract
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Problems solved by technology

[0008] The sulfuric acid decomposition process of calcium fluoride: different from the sulfuric acid decomposition of apatite, hydrofluoric acid (volatile escape) is produced instead of phosphoric acid, which cannot play the role of complexing calcium, and the concentration of sulfuric acid used is also very high , resulting in a large amount of spontaneous nucleation of calcium sulfate, encapsulating fluorite powder to hinder the reaction

Method used

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  • Method for producing hydrofluoric acid from fluorite as raw material
  • Method for producing hydrofluoric acid from fluorite as raw material

Examples

Experimental program
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Effect test

Embodiment 1

[0029] Fluorite ore (with CaF 2 97.2%) 1kg to prepare a mixed solution of phosphoric acid and sulfuric acid, P 2 O 5 The content is 25%, the concentration of sulfuric acid is controlled at 200g / L, the amount of dihydrate gypsum seed crystals added is 100g, the liquid-solid ratio is 10:1, the reaction temperature is 90°C, and the reaction time is 4h. The XRD pattern and SEM pattern of the obtained decomposition slag are as follows figure 1 and figure 2 shown. Under these conditions, CaF 2 The decomposition rate is 99.5%. After the reaction, filter, add the consumed sulfuric acid to the filtrate and return to a new round of leaching of fluorite ore powder. The HF gas generated during the reaction is evacuated and condensed, then absorbed and dehydrated by concentrated sulfuric acid, and further rectified to obtain hydrogen fluoride acid.

Embodiment 2

[0031] The filtrate that embodiment 2 produces is filled into sulfuric acid to decompose fluorite ore (containing CaF2) later to 200g / L 2 97.2%), dihydrate gypsum seed crystal addition 100g, liquid-solid ratio 10:1, reaction temperature 90 ℃, reaction time 4h, under this condition, CaF 2 The decomposition rate is 99.3%. After the reaction, filter, add the consumed sulfuric acid to the filtrate and return to a new round of leaching of fluorite ore powder. The HF gas generated during the reaction is evacuated and condensed, then absorbed and dehydrated by concentrated sulfuric acid, and further rectified to obtain hydrogen fluoride acid.

Embodiment 3

[0033] Fluorite ore (with CaF 2 97.2%) 1kg to prepare a mixed solution of phosphoric acid and sulfuric acid, P 2 O 5 The content is 35%, the concentration of sulfuric acid is controlled at 250g / L, the amount of dihydrate gypsum seed crystals added is 10g, the liquid-solid ratio is 5:1, the reaction temperature is 60°C, and the reaction time is 8h. Under these conditions, CaF 2 The decomposition rate is 98.4%. After the reaction, filter, add the consumed sulfuric acid to the filtrate and return to a new round of leaching of fluorite ore powder. The HF gas generated during the reaction is evacuated and condensed, then absorbed and dehydrated by concentrated sulfuric acid, and further rectified to obtain hydrogen fluoride acid.

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Abstract

The invention discloses a method for producing hydrofluoric acid from fluorite as a raw material. The preparation process of the hydrofluoric acid is carried out in airtight reaction equipment. The method comprises the following steps of: mixing fluorite mineral powder and a mixed solution of phosphoric acid and sulfuric acid to form a mixed solution; adding the new mixed solution into an airtight reactor and reacting; adding dihydrate gypsum as a seed crystal and controlling the concentration of the phosphoric acid, the content of P2O5 and the reaction temperature to obtain favorable dihydrate gypsum with excellent filtering and washing performances; vacuumizing HF gas generated in the reaction process, exhausting and condensing; carrying out absorption and dehydration on the condensed HF gas by concentrated sulphuric acid; further rectifying the dehydrated gas to obtain the hydrofluoric acid; and complementing and decomposing the consumed sulfuric acid by using the defluorinated concentrated sulphuric acid and enabling the defluorinated concentrated sulphuric acid and filtrate to return to a new round of leaching step of the fluorite mineral powder. The method disclosed by the invention has the advantages that high-efficiency decomposition of fluorite mineral is realized and the leaching rate of fluorine reaches over 98 percent; the recycling of the sulfuric acid is basically realized, so that the leaching cost is greatly reduced; and the leaching equipment is simple in structure, convenient to operate and easy to realize the industrialization.

Description

technical field [0001] The invention relates to the preparation of hydrofluoric acid in the field of fluorine chemical industry, in particular to a method for producing hydrofluoric acid by using fluorite as a raw material. Background technique [0002] Hydrofluoric acid is widely used in industry, national defense and civil use. For example, it is used in the production of freon refrigerants, fluorine-containing resins, aluminum fluoride, etc., and is used as a catalyst in the petroleum industry. It can also be used as a raw material for uranium hexafluoride in the atomic energy industry and nuclear weapon production. [0003] At present, the main method of producing hydrofluoric acid is the fluorite-sulfuric acid method. The thermodynamic trend of the reaction between sulfuric acid and fluorite is great, but the CaSO generated during the reaction process 4 The solid film will cover the surface of the unreacted fluorite, which will affect the further progress of the react...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B7/19
Inventor 赵中伟李江涛陈星宇陈爱良刘旭恒
Owner CENT SOUTH UNIV
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