Sintering-alkaline processing of borosilicate ores of Tajikistan

The aim of the work is to study the processes of decomposition of boron-containing ore by sintering with NaOH, finding the optimal parameters of the decomposition process, studying the kinetics of processes and developing the technological foundations for ore processing. The processes of borosilicate ore processing were studied by sintering with NaOH. Possible mechanisms of chemical reactions of the process of sintering-alkaline decomposition of boron-containing ore are established, the results of which are substantiated by physicochemical methods of analysis. A principal technological scheme for processing of borosilicate ores by a sintering-alkaline method has been developed. In the first chapter, data on alkaline and caking processes for processing boron-containing and aluminium comprising raw materials are available in the literature. Based on this, the directions of our own research are outlined. The second chapter is devoted to the study of the chemical and mineralogical compositions of borosilicate ores and their concentrates with the help of X-ray phase and chemical analysis methods, the stoichiometric calculation of the formation of aluminum, iron, and boron salts has been carried out, and a thermodynamic analysis of the processes of sintering borosilicate ores with alkali has been considered. The third chapter presents the results of a study of sintering-alkaline method of processing of initial borosilicate ore of the Ak-Arkhar Deposit and its concentrate without calcination and after calcination. The kinetics of sintering of borosilicate ores with sodium hydroxide was studied. The optimal conditions of borosilicate ore sintering before and after the preliminary calcination with alkali were determined. Optimal parameters of the sintering process have been found: sintering temperature 800-8500 deg C, duration of the process - 60 minutes, mass ratio of NaOH to raw materials 2: 1. The conditions for sintering of borosilicate concentrate with alkali have been determined and rational conditions of the sintering process have been found: the sintering temperature is 800-8500 deg C, the process duration is 60 minutes with mass ratio of NaOH to the raw material of 1: 1. Decomposition conditions of the calcined boron concentrate, where the maximum recovery of the boron product was 92, 8% have been defined. The results of studies on elaboration of basic technological scheme of boron products obtaining from borosilicate ores of Ak-Arkhar Deposit by sintering method have been discussed. The flowsheet of obtaining of boron products from the borosilicate ores of Ak-Arkhar Deposit by sintering-alkaline method have been developed. The process consists of the following stages: baking at 900-950 deg C, alkaline sintering, leaching with water at 80 deg C, pulp filtration, crystallization of the product, separation and drying. (author)