CN1337357A - Method of preparing rare earth fluoride - Google Patents

Abstract

The method for preparing rare earth fluoride incldues the procedures of fluorination, washing, filtering, drying and vacuum dehydration, and is characterized by that the fluorination procedure adopts fluohydric acid and ammonia water and mixes them into the compound fluorination agent, and mixes the fluorination agent with rare earth material liquor, and makes them undergo the processes of fluorination and precipitation to obtain the hydrated rare earth fluoride. The granule of said hydrate rare earth fluoride is large, easy to precipitate, clearing time can be shortened to tens min., it is easy to wash, the impurities of excess HF, Cl and others can be easily removed, its product quality is high, rare earth recovery rate is high, and its production cost is low.

Description

Method for preparing rare earth fluoride

The present invention belongs to the field of wet metallurgical technology.

The preparation method of rare earth fluoride in the prior art mainly comprises the following steps: hydrogen fluoride gas fluorination, ammonium bifluoride dry fluorination, and wet fluorination.

The hydrogen fluoride gas fluorination method is to charge rare earth oxide into a fluorination furnace, then dry anhydrous hydrogen fluoride gas is introduced into the fluorination furnace, and the hydrogen fluoride gas and rare earth oxide are in contact reaction under the heating condition to generate the rare earth fluoride.

The dry fluorizating method of ammonium bifluoride is that rare earth oxide and excessive ammonium bifluoride are mixed in proportion and put into a fluorizating furnace to react under heating condition to produce rare earth fluoride. The method has the disadvantages of severe equipment corrosion at high temperature, high ammonium bifluoride cost and low equipment utilization rate.

The wet fluoridation method is that hydrofluoric acid is added into rare earth solution to precipitate hydrated rare earth fluoride, then the hydrated rare earth fluoride is washed by water to remove impurities such as HF, CL and the like, and anhydrous rare earth fluoride is prepared by filtration, drying and vacuum dehydration. The method has the advantages of large production batch, simple equipment and more application in production. But the hydrated rare earth fluoride precipitated by hydrofluoric acid is colloidal, has fine particles and the average particle diameter D₅₀About 0.28 mu m, so the filter cloth is difficult to settle and wash, the filter cloth is easy to penetrate during filtration, the operation is inconvenient, the production period is long, the rare earth loss is large, and the impurity content in the product is high.

In recent years, it has been proposed to convert rare earth fluoride with hydrofluoric acid in rare earth carbonate slurry by adding a rare earth carbonate preparation step, which causes inconvenience in handling due to generation of a large amount of bubbles when rare earth carbonate is converted with hydrofluoric acid, and to obtain rare earthfluoride particles having an increased average particle diameter D₅₀About 0.6 μm, but is still not ideal.

The invention aims to provide a method for preparing rare earth fluoride, which overcomes various defects of the methods for preparing rare earth fluoride and ensures that rare earth fluoride precipitate particles are large, the operation is easy, the equipment is simple, the production batch is large, the product quality is high and the production cost is low.

The technical scheme of the invention is as follows: the method for preparing rare earth fluoride comprises the working procedures of fluorination, washing, filtering, drying and vacuum dehydration, and is characterized in that: in the fluorination process, hydrofluoric acid and ammonia water are mixed to prepare a composite fluorinating agent, and rare earth feed liquid and the composite fluorinating agent are mixed to perform fluorination precipitation to obtain hydrated rare earth fluoride.

When hydrofluoric acid and ammonia water are mixed to prepare the composite fluorinating agent, the molar ratio of the hydrofluoric acid to the ammonia water is 1: 0.6-0.95.

When the rare earth feed liquid is mixed with the composite fluorinating agent, the dosage of hydrofluoric acid is 105-120% of the theoretical amount of rare earth. Washing the hydrated rare earth fluoride with water, drying the filtered filter cake at the temperature of 100-120 ℃, and dehydrating at the temperature of 600-620 ℃ for 4-6 hours in vacuum to prepare the anhydrous rare earth fluoride.

Example (b):

thin paper Soil for soil Material Liquid for treating urinary tract infection	Name of rare earth feed liquid	Example 1 Yttrium chloride solution	Example 2 Dysprosium chloride solution
				Volume of feed liquid (liter)	100	100
	Rare earth concentration (RE)2O3Mole/liter)	0.92	1.1
				pH of feed liquid	4.8	5.1
	Rare earth weight (RE)2O3Kilogram)	10.39	20.52
				Compound medicine Combination of Chinese herbs Fluorine Transforming Agent for treating cancer	Hydrofluoric acid concentration (%)	50	50
Hydrofluoric acid dosage (liter)	10.9	13.2
			Concentration of Ammonia (N)		6.0	6.8
Amount of ammonia (liter)	42.0	50.2
			Knot Fruit		Average particle diameter D of hydrated rare earth fluoride50(μm)	1.39	1.37
Product name	Anhydrous yttrium fluoride	Anhydrous dysprosium fluoride
				Product weight (kilogram)	13.42	24.14
Rare earth recovery (%)	99.52	99.68
				Product produced by birth Article (A) Quality of food Measurement of	RE2O3(％)	77.05	84.72
F(％)	38.86	25.69
			H2O(％)		＜0.20	＜0.20

The implementation operation process comprises the following steps:

1. adjusting the pH value of the purified and impurity-removed rare earth solution (including rare earth chloride, rare earth nitrate and rare earth sulfate solution) to 2.0-5.4, wherein the rare earth concentration is RE₂O₃0.5-1.5 mol/l of rare earth feed liquid.

2. Adding 4-10N ammonia water into hydrofluoric acid, mixing and stirring to prepare a composite fluorinating agent, and adding HF and NH₃·H₂The molar ratio of O is 1: 0.6-0.95. The chemical reaction formula is as follows:

3. according to the dosage of hydrofluoric acid being 105% -120% of rare earth theoretical quantity, the rare earth feed liquid and the composite fluorinating agent are mixed and stirred, and the hydrated rare earth fluoride is obtained by fluorination and precipitation. The chemical reaction formula is as follows:

4. washing the precipitated hydrated rare earth fluoride with water, filtering, drying a filter cake at the temperature of 100-120 ℃, and dehydrating at the temperature of 600-620 ℃ in vacuum for 4-6 hours to prepare the anhydrous rare earth fluoride.

Claims (4)

1. The method for preparing rare earth fluoride comprises the working procedures of fluorination, washing, filtering, drying, vacuum dehydration and the like, and is characterized in that: in the fluorination process, hydrofluoric acid and ammonia water are mixed to prepare a composite fluorinating agent, and rare earth feed liquid and the composite fluorinating agent are mixed to perform fluorination precipitation to obtain hydrated rare earth fluoride.

2. The method as set forth in claim 1, wherein the molar ratio of hydrofluoric acid to ammonia water is 1: 0.60-0.95 when the hydrofluoric acid and ammonia water are mixed to prepare the composite fluorinating agent.

3. The method as set forth in claim 1, wherein the amount of hydrofluoric acid used in the mixing of the rare earth feed solution and the composite fluorinating agent is 105-120% of the theoretical amount of rare earth.

4. The method as set forth in claim 1, characterized in that the hydrated rare earth fluoride is washed with water, filtered, the filter cake is dried at 100-120 ℃, and then dehydrated for 4-6 hours at 600-620 ℃ in vacuum to prepare anhydrous rare earth fluoride.