Research On Leaching Process Of Colemanite And Ulexite Ores By Acid

As a relative scarce chemical mineral resource, boron mineral is mainly used as the raw materials of boric acid and borax. A variety of boron compounds with using boric acid as raw materials have been widely used in many fields such as chemical industry, light industry, pharmacy, electronic, metallurgy, aerospace, power, solar energy, nuclear industry, agriculture and so on. Therefore, boron minerals play a significant role in the national economy. Ascharite resource which is the main resource in our country over the past few decades has run out due to a long period of mining, and can’t meet the needs of future boron industry. As a result, to speed up rational utilization of other boron resources is meaningful to the development of boron industry in our country. The research topics in this paper have two parts:the research on the chemical engineering process of boric acid preparation by using sulphuric acid to decompose Turkey’s Colemanite Ore, and the research on the decomposition process of Ulexite Ore in Bolivia by using sulphuric acid, with the removal of chloride by washing ore.Turkey’s Colemanite Ore was characterized by chemical analysis and XRD, and the chemical composition of Colemanite Ore is as follows:B2O341.82%, CaO26.75%and MgO1.71%. Colemanite Ore is mainly composed of Colemanite (2Ca0·3B203·5H2O), brushite, jennite and insoluble impurities such as silicate. The effects of liquid to solid ratio and sulfuric acid consumption on the reaction of Colemanite Ore with sulfuric acid were investigated and the results indicated that under the conditions of98%sulfuric acid theory consumption, temperature90℃, reaction time1h and reaction liquid to solid ratio4:1, the boron leaching rate could reach up to98.16%. With the reaction of Colemanite Ore with sulfuric acid carried out under these conditions, mother liquor and washing water recycles have been investigated, the experiment data showed that the better cycle time is secondary. The recovery process of boron from the mother liquor by the reaction of calcium hydroxide with boric acid has also been investigated and the results indicated that under the conditions of temperature25℃, CaO/B2O31.6:1, reaction time1.5h calcium metaborate can be precipitated, after characterizing by chemical analysis, the contents of different components were showed as follows:B2O328.38%, CaO36.21%and MgO2.50%. After the reaction of Colemanite Ore with sulfuric acid, CaSO4·2H2O was formed with brushite in the reaction slurry. Adding anionic polyacrylamide for filter aid can improve the filtration of the reaction slurry due to forming CaSO4·2H2O with larger crystal size, the filtration rate has been sped up, and the filtration time hass been shorten. Bolivia’s Ulexite Ore was characterized by chemical analysis and XRD, the chemical composition of Ulexite Ore is as follows:B2O325.31%, CaO12.36%, Na2O7.09%, MgO2.21%and Cl-4.95%. Ulexite Ore is mainly composed of Ulexite (NaCaB5O9·8H2O), NaCl and SiO2. After washing with deionized water, the content of Cl-can be reduced to0.91%. The results on the reaction of Ulexite Ore with sulfuric acid indicated that under the conditions of84%sulfuric acid theory consumption, temperature90℃, reaction time Ih and reaction liquid to solid ratio3:1, the boron leaching rate could reach up to98.5%. Mother liquor and washing water recycles have been investigated, the experiment data showed that the better cycle time is secondary. The recovery process of boron from the mother liquor by the reaction of calcium hydroxide with boric acid has also been investigated and the results indicated that under the conditions of temperature18℃, CaO/B2O33:1, reaction time3h calcium metaborate can be precipitated.