CN1371866A

CN1371866A - Technology and equipment for preparing rarearth fluoride by fire method direct fluoridation

Info

Publication number: CN1371866A
Application number: CN 01108825
Authority: CN
Inventors: 金石; 金泉; 赵景环; 王堂; 王有山
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-02-23
Filing date: 2001-02-23
Publication date: 2002-10-02

Abstract

The present invention relates to a technological process for preparing rare-earth fluoride by utilizing pyrogenic process to make direct fluorination and its equipment. Its equipment includes gas storage tank, heating furnace and tail gas recovering device, the heating furnace is respectively connected with gas storage tank and tail gas recovering device by means of gas pipelines, and its preparation process includes the following steps: uniformly mixing rare earth oxide and ammonium hydrogen fluoride according to weight ratio of 1:0.1-0.3, placing them into a container, heating and introducing HF gas, heat insulating, heating and more heat-insulating, then naturally coodling so as to complete said preparation process.

Description

Process and equipment for preparing rare earth fluoride by direct fluorination by pyrogenic process

The invention relates to a process and equipment for preparing rare earth fluoride by direct fluorination by a pyrogenic process.

The rare earth industry in China is a new industry and plays an increasingly important role in various fields of national economy. China is a big rare earth country, most countries import rare earth products from China, and particularly 80% of rare earth products in China such as Japan, America, UK and the like are imported from China. In recent years, with the market of ndfeb magnetic materials being developed, the application range of metal neodymium as the main raw material of the ndfeb magnetic material and metal dysprosium as the main additive for improving the performance of the magnetic material is increasingly expanded. According to statistics, 3500 tons of neodymium metal and 500 tons of dysprosium metal are needed in 2000, the demand of neodymium iron boron in the world is increased at a speed of 12-15% every year, and the growth rate of neodymium iron boron in China is kept above 20%. Therefore, improvements in the production process and productivity of neodymium fluoride and dysprosium fluoride, which are essential raw materials for neodymium metal and dysprosium metal, are also imperative.

Because the rare earth fluoride is increasingly widely applied in various fields, the demand of the international market for the rare earth fluoride is very large, and the direct export of neodymium fluoride, dysprosium fluoride and terbium fluoride has higher and higher earning money. The prior process for producing rare earth fluoride mainly comprises wet fluorination, and the process flow is as follows:

from the process conditions it can be seen that: the wet process for preparing rare earth fluoride includes dissolving rare earth oxide in hydrochloric acid to convert it to rare earth chloride, and replacing chlorine radical in rare earth chloride with hydrofluoric acid to form rare earth fluoride precipitate. Both the two chemical reactions are exothermic reactions, and people can be injured by overflowing a trough (spraying base) if a worker carelessly operates the chemical reaction. After the rare earth fluoride is precipitated, supernatant liquid needs to be sucked out by a vacuum siphoning method and needs to be washed for three times, and in the process, a large amount of waste hydrochloric acid and waste hydrofluoric acid are discharged into a sewer to cause environmental pollution. The washed rare earth fluoride also needs to be dried and dehydrated by electric heating, and the energy consumption is very large. In addition, the yield of rare earth fluoride is not very high.

The invention aims to provide a process and equipment for preparing rare earth fluoride by direct fluorination by a pyrogenic process, which can improve the working environment of workers, prevent environmental pollution caused by the preparation of the rare earth fluoride, reduce energy consumption and improve the yield of the rare earth fluoride.

The purpose of the invention is realized by the following modes:

uniformly mixing rare earth oxide and ammonium bifluoride according to the weight ratio of 1: 0.1-0.3, placing the mixture into a container with holes, then placing the container into a heating furnace, slowly heating the heating furnace to 350 ℃ for heat preservation for 2-4 hours, then heating to 700 ℃ for heat preservation, starting to introduce HF gas into the heating furnace, preserving heat for 2-5 hours, slowly heating to 900 ℃ for heat preservation for 5-8 hours, stopping heat preservation, naturally cooling the heating furnace, opening the heating furnace when the temperature is reduced to below 100 ℃, and taking out the well-fluorinated rare earth fluoride.

The equipment of the invention comprises a gas storage tank, a heating furnace and a tail gas recovery device, and is characterized in that the gas storage tank is connected with a furnace body of the heating furnace through a gas guide pipeline, the tail part of the heating furnace is provided with a gas outlet, the gas outlet is connected with the tail gas recovery device through an exhaust pipe, the heating furnace is composed of a base, a furnace shell, a furnace cover, a heat insulation layer, an electric heating element and an insulation layer, the electric heating element is arranged in the upper layer and the lower layer in the furnace shell, and the tail gas recovery device is a.

The invention has the advantages that: the process is simple, convenient and safe to operate, free of environmental pollution such as waste water and gas and low in energy consumption, and the rare earth fluoride produced by the process is good in quality and high in yield, and the cost is reduced.

Embodiments of the invention are given below with reference to the accompanying drawings:

fig. 1 is a schematic structural diagram of the dedicated apparatus of the present invention.

Referring to the attached drawings, the equipment comprises an HF gas storage tank (1), a heating furnace (13) and a tail gas recovery device (10), wherein the gas storage tank (1) is connected with the heating furnace (13) through a gas guide pipeline (2), the tail part of the heating furnace (13) is provided with a gas outlet, the gas outlet is connected with the tail gas recovery device (10) through an exhaust pipe (8), the heating furnace (13) is composed of a base (9), a furnace shell (5), a furnace cover (3), a heat insulation layer (12), an electric heating element (4) and an insulation layer (11), the gas guide pipeline (2) and the exhaust pipe (8) are both copper pipes, the electric heating element (4) can be an electric heating wire or an electric heating rod, and the electric heating element is arranged in the furnace shell (5. The tail gas recovery device (10) is a container filled with clean water.

The equipment for preparing rare earth fluoride by direct fluorination by a pyrogenic process is easy to operate, has simple process, is a new technology which is easy to master by workers, and has the following process flow:

the rare earth oxide and the ammonium bifluoride are uniformly mixed according to the weight ratio of [ 1: 0.1-0.3]and are filled into a perforated circular box (7) with the diameter of phi 370 multiplied by 200mm, the box is put into a heating furnace (13) made of cast iron material, and a furnace cover (3) is covered. And (3) power supply, slowly heating to 350 ℃ for 250-. And introducing the excessive hydrogen fluoride gas into a tail gas recovery device (10) for recovery to prepare hydrofluoric acid. The dysprosium fluoride prepared by the process has the production ratio of 1: 1.16, the neodymium fluoride has the production ratio of 1: 1.185, and the yield is much higher than that of rare earth fluoride prepared by a temperature method.

Claims

1. A process for preparing rare earth fluoride by direct fluorination by pyrogenic process is characterized in that rare earth oxide and ammonium bifluoride are uniformly mixed according to the weight ratio of 1: 0.1-0.3, the mixture is placed into a container with a hole, then the container is placed into a heating furnace, the heating furnace is slowly heated to 350 ℃ for heat preservation for 2-4 hours, then the heating furnace is heated to 700 ℃ for heat preservation for 2-5 hours, then the heating furnace is slowly heated to 900 ℃ for heat preservation for 5-8 hours, then the heat preservation is stopped, the heating furnace is naturally cooled, and when the temperature is reduced to below 100 ℃, the heating furnace is opened, and the well fluorinated rare earth fluoride is taken out.

2. The equipment for preparing rare earth fluoride by direct fluorination by pyrogenic process comprises a gas storage tank, a heating furnace and a tail gas recovery device, and is characterized in that the gas storage tank is connected with a furnace body of the heating furnace through a gas guide pipeline, the tail part of the heating furnace is provided with a gas outlet, the gas outlet is connected with the tail gas recovery device through a gas exhaust pipe, the heating furnace is composed of a base, a furnace shell, a furnace cover, a heat insulation layer, an electric heating element and an insulation layer, and the electric heating element is arranged in the furnace shell in an upper layer.

3. The apparatus of claim 2, wherein the electrical heating element is a heating wire or a heating rod.

4. The apparatus of claim 2 wherein the off-gas recovery device is a water container.