The strontium ore processing technology actually processes the lapis lazuli concentrate into various strontium salts such as SrCo3, Sr(No3)2, SrCl2, and SrTiO3. However, among the many strontium salts, the most important one is SrCo3, which is not only the most widely used, but also the most widely used, and can be converted into other forms of strontium salts.
The production methods of SrCo3 mainly include reduction method and metathesis method, but the former is mostly. However, the technical requirements for strontium carbonate products at home and abroad are slightly different.
The reduction method is also called black ash method, that is, after high temperature roasting, SrSo4 is converted into SrCo3. The main chemical reactions are:
SrSo4+2C 1300°C SrS+2CO2↑(1)
SrS+NaCo3 Na2S+SrCo3↓ (2)
Or: SrS+Co2 SrCo3↓+So2↑(3)
The metathesis method mainly uses a soda ash or ammonium hydrogencarbonate to undergo a metathesis reaction with diatomite after calcium removal to form crude cesium carbonate. Acid-soluble, refined and then reacted with soda ash or ammonium bicarbonate to form SrCo3.
Both the double decomposition method and the reduction method have their own strengths. In terms of product quality, the difference between the two is small; but in terms of cost, because the meta-decomposition process is long and requires a lot of chemical raw materials, the cost is more than 40% higher than the reduction method. This is perhaps one of the main reasons why most manufacturers choose the reduction method. The biggest advantage of the double decomposition method is that the waste liquid is easy to handle, which is not comparable to the reduction method.
The pollution of sulfur-containing waste liquid in the production of reduction has attracted the attention of countries all over the world. In the past few years, the Lishui Chemical Plant in Jiangsu Province has tried to treat the ammonium sulphate waste liquid by gas stripping method, and has received good results. The foreign country replaces Na2Co3 with Co2 to carbonate the SrS refining liquid, thus avoiding the generation of sulfur-containing waste liquid. At present, there are still a number of new processes and new equipment being tested. Reducing pollution is one of the main directions in the development of the reduction method.
A new method currently being tested in China is to directly convert SrSo4 into SrCo3 by means of leaching, which is extremely attractive for reducing costs and reducing pollution. The specific method is to directly leach the lapis lazuli concentrate by using a sodium carbonate solution as a leaching agent. The ore used in the test is a natural high-grade lapis lazuli ore. The ore is crushed, ground, and sieved into several grades of -65+100, -100+150, -150+200, -200+250, -250+325 mesh for testing. The content of (Ba+Ca) impurities in the sample was <1%. The leaching test was carried out in a 0.25 L flask. The leaching agent Na2Co3 concentration was 0.2 mol, the leaching time was 300 min, the temperature was 328 K, and the pH was 8-12. The results showed that the leached products were all SrCo3. This method is currently in the experimental phase.
The new technologies introduced in the past two years in China mainly include calcium method and thermal method.
The main process of the calcium method is the reduction-metalysis one-step conversion method, which is black ash mainly composed of ruthenium chloride, and then refined by water, refined and then reacted with ammonium hydrogencarbonate to prepare SrCo3. The main chemical reactions are:
SrSo4+4C+CaCl2 SrCl2+CaS+4CO↑
SrCl2+NH4HCo3 SrCo3↓+NH2↑
A chemical plant in Sichuan Province has used this process to produce qualified SrSo4 products. Dazu Sichuan ore, copper beams, Aikawa production celestite containing SrSo470% ~ 85%, CaSo4> 8% ~ 15%, BaSo43% ~ 15%; SrSo3 product purity of 97%, CaCo3≤1.
The shortcoming of this process is that the intermediate agent CaCl2 in the calcium production has a great influence on the product cost. Recently, the price of CaCl2 has risen, which has led to an increase in the cost and price of SrCo3. Further, the precipitation reaction, ammonium hydrogencarbonate aqueous solution, a large loss; alkaline earth metal separation, the loss rate is high strontium salt.
The thermal method is a new process based on the reduction method. The process was designed by the Sichuan Huzhou Chemical School and the Sichuan South-East Geological Team to handle the only diamond-mining mine in Sichuan. The process is as follows: firstly mixing the antimony ore and coke in a certain ratio, and then calcining at a high temperature of 1290 ° C; the clinker containing Sro and other metal oxides is leached with water to prepare a crude mash; after precipitation, filtration After removing impurities, NH4HCo3 is added to form a SrCo4 precipitate; finally, it is separated, dried, and pulverized to obtain a product.
The joint factory has used this process to produce the province's first-class SrSO3 products with an annual output of 500t. The raw materials used were the Linglong Mine in Tongliang County, Sichuan Province. The ore contains 79.39% SrCo3; 19.06% CaCo3; 0.3% NgCo3; 0.31% Fe2O3. The purity of SrCo3 is as high as 98.69%; Fe2O30.0054%; CaO0.22%; C1- 0.009%; all indexes exceed Sichuan foreign trade standards. Almost all products are exported. In addition, the final leaching residue in the production process can also be used in the construction industry. The clear liquid separated from the slurry is dilute ammonia water, which can be used for agricultural production and also recovers ammonia hydrogencarbonate. This allows the raw materials to be comprehensively utilized. At present, the main problem in production is that the process conditions of calcination and leaching are difficult to control, and the ruthenium in the ore is difficult to be recycled, and the ruthenium contained in the leaching residue needs to be recovered by acid treatment.
The processing of other tellurides and metal ruthenium is based on SrCo3:
The SrCo3 is placed in a cylinder reactor, and concentrated nitric acid is added to react to form a cerium nitrate product:
SrCo3+2HNo3 Sr(No3)2+H2o+Co2↑
Barium chloride is obtained by the action of barium carbonate and hydrochloric acid:
SrCo3+2Hcl 〖FY2〗 SrCl2+H2o+Co2↑
The cerium oxide can be obtained by heating cerium carbonate. The metal ruthenium can be obtained by a thermal reduction reaction of ruthenium oxide with aluminum metal, or an oxide of molten ruthenium or electrolysis of ruthenium chloride.
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