Process for preparing ammonium dimolybdate crystal by using sulfuric acid and molybdenum calcine

An ammonium dimolybdate and process method technology, applied in chemical instruments and methods, molybdenum compounds, inorganic chemistry and other directions, can solve the problems of difficult quality control, low single batch yield, long process flow, etc. The effect of lower production cost and continuous production process

Inactive Publication Date: 2012-04-18
HENAN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most of the ammonium dimolybdate products on the market today are in the form of powder, mainly made from molybdenum calcined sand, treated with nitric acid, and evaporated and concentrated.
At present, the existing domestic and foreign methods for preparing ammonium dimolybdate crystals mainly use ammonium tetramolybdate as raw material, need to add seed crystals, and produce intermittently. The process is long, the quality is not easy to control, and the single batch yield is low. , the production cost is relatively high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] At room temperature, dissolve 1000g of molybdenum calcine, 30g of ammonium sulfate and 10g of ammonium persulfate into 2500ml of water, then slowly and continuously add 160ml of 90% sulfuric acid drop by drop, and keep stirring. After the dropwise addition is completed, heat up to 75°C , continuous reaction for 0.5 hours; after the reaction, filter and wash the filter cake 3 times with dilute sulfuric acid with a mass concentration of 1% heated to 75°C in advance, the volume of dilute sulfuric acid used each time is 480ml, and then wash the filter cake with the same volume of water Cake twice to obtain a wet filter cake with a moisture content of 10%; dissolve 1200g of the wet filter cake into 1000ml of ammonia water with a mass concentration of 15% at room temperature, stir continuously, raise the temperature to 50°C, and dissolve for 30 minutes. Use 15% ammonia water to regulate the pH value of the solution to be equal to 8, and filter while it is hot to obtain a light...

Embodiment 2

[0021] At room temperature, dissolve 1000g of molybdenum calcine, 50g of ammonium sulfate and 70g of ammonium persulfate into 3000ml of water, then slowly and continuously add 270ml of 98% sulfuric acid drop by drop, and keep stirring. After the dropwise addition is completed, heat up to 95°C , continuous reaction for 1 hour, after the reaction, filter, wash the filter cake 3 times with dilute sulfuric acid with a mass concentration of 3% heated to 95°C in advance, the volume of dilute sulfuric acid used each time is 800ml, and then wash the filter cake with the same volume of water Cake 3 times to obtain a wet filter cake with a moisture content of 15%; dissolve 1600g of wet filter cake into 1000ml of ammonia water with a mass concentration of 18% at room temperature, stir continuously, raise the temperature to 65°C, and dissolve for 60 minutes. Use 18% ammonia water to adjust the pH value of the solution to 8, and filter it while it is hot to obtain a light blue transparent f...

Embodiment 3

[0024]At room temperature, dissolve 1000g of molybdenum calcine, 40g of ammonium sulfate and 40g of ammonium persulfate into 2800ml of water, then slowly and continuously add 217ml of 95% sulfuric acid drop by drop, and keep stirring. After the dropwise addition is completed, heat up to 85°C , continuous reaction for 0.7 hours; after the reaction, filter, and wash the filter cake 4 times with dilute sulfuric acid with a mass concentration of 2% heated to 85°C in advance, the volume of dilute sulfuric acid used each time is 640ml, and then wash the filter cake with the same volume of water Cake twice to obtain a wet filter cake with a moisture content of 12%; dissolve 1400g of wet filter cake into 1000ml of ammonia water with a mass concentration of 17% at room temperature, stir continuously, raise the temperature to 60°C, and dissolve for 45 minutes. Use 17% ammonia water to regulate the pH value of the solution to be equal to 9, and filter while it is hot to obtain a light blu...

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PUM

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Abstract

The invention provides a process for preparing ammonium dimolybdate crystal by using sulfuric acid and molybdenum calcine. The method comprises steps of: (1) mixing molybdenum calcine, ammonium sulfate, ammonium persulfate and water and carrying out a pretreatment by sulfuric acid; (2) carrying out ammonia leaching by ammoniacal liquor to obtain an ammonium molybdate solution; (3) adding ammoniumsulphide for purification and removing metal impurity ions in the ammonium molybdate solution; (4) evaporating, concentrating and crystallizing a clean fluid to a certain solution proportion and pH value, adding ammoniacal liquor, regulating and control quantity of nucleus to promote crystal growth, carrying out hot pumping filtration and drying to obtain the ammonium dimolybdate crystal. The invention has continuous technology, simple process, and increased efficiency and needs no seed addition; nitric acid is substituted by sulfuric acid to lower cost; a product crystal has an average Fsss of 337 mum, an average particle size distribution d0.5 of 412 mum and an average loose specific weight of 1.329g.cm<-3>.

Description

technical field [0001] The invention relates to a technique in the field of inorganic chemical industry, in particular to a process method for preparing ammonium dimolybdate crystals by using sulfuric acid and molybdenum calcined sand. Background technique [0002] Ammonium molybdate is a typical isopolysalt, the main varieties are ammonium dimolybdate, ammonium tetramolybdate, ammonium heptamolybdate, ammonium octamolybdate, ammonium dodecamolybdate and β-ammonium tetramolybdate, etc. Most of the ammonium molybdate used in industry is a mixture of the above ammonium molybdate series in different proportions, which is prone to agglomeration (block) in different degrees. Ammonium molybdate is mainly used to produce metal molybdenum powder. Its crystal form, structure, particle size, particle size distribution and dispersibility have a great influence on the physical and chemical properties of molybdenum powder products and the processing performance of molybdenum powder. The...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G39/00
Inventor 张军卢伟伟郭旭明闫焉服郭彦辉许明臣郭红波陈宁
Owner HENAN UNIV OF SCI & TECH
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