Selective Recovery of Mushistonite from Gravity Tailings of Copper–Tin Minerals in Tajikistan

Lei Sun, Yuehua Hu, Wei Sun, Zhiyong Gao, Mengjie Tian
2017 Minerals  
Tajikistan has abundant copper-tin resources. In this study, mineralogical analysis of copper-tin ores from the Mushiston deposit of Tajikistan indicates that tin mainly occurred in mushistonite, cassiterite, and stannite, while copper mainly occurred in mushistonite, malachite, azurite, and stannite. The total grades of tin (Sn) and copper (Cu) were 0.65% and 0.66%, respectively, and the dissemination size of copper-tin minerals ranged from 4 µm to over 200 µm. Coarse particles of copper-tin
more » ... nerals were partially recovered by shaking table concentrators with a low recovery rate. Based on the mineralogical analysis, flotation recovery was used for the first time on the fine particles of copper-tin minerals, including mushistonite, from shaking table tailings. Single factor flotation experiments, open circuit flotation tests, and closed circuit flotation tests were performed to determine the optimized flotation conditions. Results indicated that benzohydroxamic acid (C 6 H 5 CONHOH) and lead nitrate could effectively recover the mushistonite, cooperating with other depressants. The final concentrate contained 13.28% Sn, with a recovery rate of 61.56%, and 18.51% Cu, with a recovery rate of 86.52%. This method proved effective for the exploitation and use of this type of copper-tin resource in Tajikistan. The factory attempted to recover the fine particle size fraction of copper and tin minerals, including mushistonite, using the sulfidation flotation method, but failed. Research studies have indicated that oxide minerals, such as cassiterite and scheelite, could establish hydroxylated surfaces in the flotation pulp. Benzohydroxamic acid (BHA) and lead ions react with the hydroxyl groups and co-absorb on the hydroxylated surface. As a result, cassiterite and scheelite could be selectively recovered by flotation, using BHA as a collector and lead nitrate as an activator [12] [13] [14] [15] [16] . According to the chemical composition and crystal structure of mushistonite mentioned above, hydroxyl groups are present within the mineral's own natural structure. The strength of the hydrogen bonds between hydroxyl groups is weak, and easily broken to form hydroxylated surfaces with grinding. We considered that hydroxyl groups on the surface of mushistonite could react with BHA and lead ions, and be selectively recovered by flotation. Based on this hypothesis, process mineralogy and the flotation of copper-tin tailings were studied to recover mushistonite. Experimental results confirmed that flotation of copper-tin tailings, using BHA as the collector, was feasible. It provided an economical and realistic method for the use of mushistonite. Materials and Methods Minerals and Reagents The raw ore samples were collected from the crushing workshop of the Yukuang Panjakent copper-tin mine concentration plant in Northwest Tajikistan. The samples used for flotation experiments were obtained from the shaking table tailings of this plant (Figure 1 ). To ensure the representativeness of the samples, sampling work was performed during the normal producing period in the plant. The sampling work was sustained for 30 min each time, one time every half day, for three continuous days. All samples were fully mixed after being dried in the natural air environment. The collector BHA was 98% pure, and other reagents used in this study, including lead nitrate as activator, sodium carbonate and hydrochloric acid as pH modifiers, carboxymethyl cellulose (CMC) and sodium fluorosilicate (SSF) as depressants, as well as terpineol as a frother, were all analytical grade. All reagents were separately dissolved into deionized water to prepare the compound solutions used in each test.
doi:10.3390/min7120242 fatcat:cyepo5rzojh2zk6f4mjy6hkcma