Study On Preparation Of Borax Through Calcining With Boron-rich Slag And Sodium-Calcium

Our nation is abundant of boron resource. Most of the resource centralized in Liaoning, Jilin, Qinghai and Tibet region. Paigeite reserve in Liaoning, accounting for64%of the country’s reserve, reaches280million tons and belongs to large boron mineral.At present ascharite is the main raw material of producing boric acid and borax. Although boron resource in Liaoning Province is rich, it nearly exhausts after60year’s mass exploitation. Therefore, it has important practical significance to speed up the development and utilization of low-grade pageite resource, which can relief boron resource tession.In terms of the low activity of boron-rich slag produced in blast furnance, CO2-soda process is not available to produce borax. Therefore, this paper puts forward a new process of preparation of Borax through sodium-calcium calcining boron-rich slag, boron-rich slag as a raw material, NaOH、Na2CO3as sodium agent, CaCO3as roasting activator, was studied by XRD、SEM, phase changes during the roasting, and then prepare borax after leaching and crystallization under normal pressure. In this study, we mainly study the effect of experimental conditions, including calcination temperature, calcination time, water-leaching time, sodium agent types, sodium agent.The results show that under the boron-rich slag dosage of10g:(1) On the condition of taking NaOH as sodium agent, calcining for2h at850℃, water-leaching for5h,5times as much for the theoretical amount of NaOH, CaCO3dosage of2g, the B2O3leaching rate is45.47%;(2) On the condition of taking Na2O3as sodium agent, calcining for2h at900℃, water-leaching for4h,6times as much as the theoretical amount of Na2CO3, CaCO3dosage of2g, the B2O3leaching rate is55.13%.(3) Compared with muffle furnace, microwave calcination is fast-heating, high-efficiency. B2O3leaching rate can reach48.95%after microwave calcination at600℃for15min.(4) Sodium-calcium calcining water-leaching filtrate, adding HC1to adjust pH to8.80～10.82, After removing SiO2through filtration, qualified borax products are available after concentrating and crystallizing filtrate at50℃.The study above improves the leaching rate of boron minerals effectively, which makes boron-rich slag calcination process and alkaline hydrolysis reaction complete at the same time, and makes boron in the slag convert to sodium borate. Compared with the early study on preparation of borax through molten sodium treatment-water leaching with boron-rich slag, the leaching rate of boron increases by24.93%. What’s more, this process is simple, less time-consuming and high-efficiency, and expected to make up for the disadvantages of present carbon dioxide-soda process which takes long time for carbonization and is strict with equipments. This process can provide a new way of recycling boron from boron-rich slag efficiently.