New Production Method Of Bismuth Powder

wallpapers Robot Tech 2021-01-15
Bismuth powder is a non-ferrous metal powder, and its appearance is light gray. It has a wide range of uses, mainly for preparing bismuth products, bismuth alloys and bismuth compounds. China's bismuth resources rank first in the world, and China has more than 70 bismuth mines, making China an absolute dominant country in bismuth in the world.
 
As a "green metal" that can be used safely, bismuth is currently not only used in the pharmaceutical industry, but also widely used in semiconductors, superconductors, flame retardants, pigments, cosmetics and other fields. It is expected to replace toxic lead, antimony, cadmium and mercury. In addition, bismuth is the metal with the strongest diamagnetism. Under the action of a magnetic field, the resistivity increases while the thermal conductivity decreases. It also has good application prospects in thermoelectric and superconductivity.
 
Bismuth is a silver-white to pink metal, brittle and easily crushed, and its chemical properties are relatively stable. Bismuth exists in the form of free metals and minerals in nature. In the past, bismuth was considered to be the most stable element with the largest relative atomic mass, but in 2003, it was discovered that bismuth has extremely weak radioactivity.

 
The technical scheme of the present invention is as follows:
1) Prepare bismuth chloride solution: take bismuth chloride stock solution with a density of 1.35 to 1.4g/cm3 and add 4%-6% acidified pure aqueous solution containing hydrochloric acid; the volume ratio of acidified pure aqueous solution to bismuth chloride stock solution is 1:1 -2;
2) Synthesis: add zinc ingots with clean surface to the prepared bismuth chloride solution; start the displacement reaction; observe the end of the reaction, when the end of the reaction is reached, take out the undissolved zinc ingots and settle for 2-4 hours; The basis for the observation and judgment of the reaction end point is: there are bubbles in the solution participating in the reaction;
3) Separate bismuth powder: extract the supernatant liquid of the precipitate in step 2) and recover zinc by conventional methods; the remaining precipitated bismuth powder is washed 5-8 times with an acidified pure aqueous solution containing hydrochloric acid 4%-6%, and then purified Rinse the bismuth powder with water until it is neutral; after the bismuth powder is quickly dried by a centrifuge, immediately soak the bismuth powder with absolute ethanol, and then spin dry;
4) Drying: The bismuth powder processed in step 3) is sent to a vacuum dryer at a temperature of 60±1°C for drying to obtain a finished bismuth powder of -300 mesh.
 
The bismuth powder produced according to the above process has the advantages that the purity of the product obtained is as high as 99%; the particle size is ultra-fine, up to -300 mesh. The chemical composition of the bismuth powder prepared by the present invention is measured: Bi>99, Fe< 0.1, O<0.5, BiO<0.1, Cr<0.01, Cu<0.01, Si<0.02, other impurities<0.18; at the same time, due to the zinc ingot replacement process, the chemical reaction only involves zinc dissolution and bismuth precipitation, avoiding a large amount of chemical production The disadvantages of gas reduce the pollution to the environment and the harm to the human body. Compared with the prior art, the whole process of the present invention is only in contact with air for a short time during the spin-drying of the centrifuge, and other processes have reaction liquid or absolute ethanol, or vacuum is isolated from oxygen, so the oxidation rate is low.

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