Leaching of zinc from aged flotation tailings of polymetallic ores using sulfate and chloride-hypochlorite solutions

The following will describe the process of how you can use mathematical modeling to organize the production of metal leaching. Mathematical models and results of computational experiments are presented. The results of studying the thickness of films of sulfuric acid-chloride solutions containing the addition of surfactants surface-active substance (SAS), which are formed when they pour out onto a frosted glass surface as a model of the surface of a piece of ore, are presented. A mathematical model how the film thickness changes depending on the feed rate of the solution and its composition, as well as on the angle of inclination of the glass surface has been determined. Underground leaching of metals from ores stimulates the search for ways and means of intensifying the process. Due to the addition of a surfactant, the leaching process is accelerated, since the thickness of the films of leaching solutions flowing over the surface of ore minerals decreases. This direction is relevant in modern science, and research in this direction the growth of indicators allows the national economy to improve and helps to improve and increase knowledge for further development of the metallurgical industry in Russia The article also discusses the results of studies on the electrochemical leaching of metals from polymetallic ore by sulfuric acid-chloride solutions with the addition of a surfactant with asymmetric current pulses. Mathematical models of the dependence of leaching indicators on the density and duration of the flow of direct and reverse polarity are presented. For ease of perception and better visualization, a table was compiled, which reflects the results of comparative analysis to assess the further possibility of processing secondary raw materials.

The article presents the results of studies on the electrochemical leaching of metals from poly-metallic ores using sulfuric acid-chloride solutions under the action of a reversible infra-low-frequency direct current with varying density and the addition of a surfactant. Mathematical models of leaching indicators have been developed depending on the density, duration of the forward and reverse polarity of the current. It is revealed that the most optimal mode is the ore leaching under the action of a reversible direct current with varying density and duration of the reverse current. It is determined that the reverse current density is 6 times greater than the forward current density, and the duration of the reverse current pulse is 0.2 of the duration of the forward current. At the same time, Kazakhstan, like other countries with the transit economy, will have to overcome the risks and challenges that have emerged as a result of global digitalization. The article shows that to stimulate digitalization of geological exploration, significant investments are needed, which will require, alongside with government regulation, searching for new forms and mechanisms of public-private partnership.

The enrichment of polymetallic sulfide ore is a complex task. Fine grinding is carried out to reveal useful minerals, resulting in the formation of microparticles. It is difficult to achieve the floatation of microparticles and fine useful minerals are lost with flotation tailings. The problem of microparticle flotation can be solved by using air bubbles smaller than 50 µmin for the flotation process. Water-air microemulsion (WAME)of a frothersolution obtained using the generator was used as microbubbles. The effect of WAME on flotation was studied on polymetallic ores and gold-bearing ore from Kazakhstan deposits.The use of WAMEin the processing of polymetallic ore allowed for themaintenance of the quality of rougher concentrates, to increase the copper extraction in Cu-Pb rougherconcentrate by 7.41%, of lead by 5.98% in the copper-lead flotation cycle (Cu-Pb-Zn-Fe ore), copper extraction in Cu-Mo rougherconcentrate by 5.2%, and molybdenum by 4.7% in the copper-molybdenum flotation cycle (Cu-Mo ore). The indicators of flotation gold extraction into the gold-containing concentrate significantly improved in comparison with the basic mode when using the generator in rougher and scavenger flotation cycles: the quality increased by 5.3 g/t, and the extraction increased by 4.27%.

We propose a technology for processing of copper-zinc ore flotation tailings with the purpose of extracting gold using ultra-low (10–30 mg/dm3 ) concentrations of NaCN. The material composition of the starting materials was examined using the methods of inductively coupled plasma, gold assay atomic absorption and X-ray diffraction analysis. The NaCN concentration in solution was determined by titrimetric and photometric methods; pH levels were determined by potentiometric analysis. The laboratory studies established optimal conditions for cyanidation of tailings resulting from flotation beneficiation of copper-zinc ores, which underwent preliminary lime treatment: mass fraction of the 0.071-mm mesh minus – 70.5%; duration – 8 h; NaCN consumption – 0.3 kg/t (at a concentration of 30 mg/dm3 ); L:S =1:1. Under these conditions, the gold extraction rate amounted to 32.0–33.6%. Pre-grinding of flotation tailings to the size of 90% of the 30 mm mesh minus led to an increase in gold extraction of up to 41.5–44.7% at an NaCN consumption of 0.6 kg/t of the same concentration and L:S =1.5:1. The results obtained served as the basis for experimental cyanidation of waste tailings according to two schemes, i.e., using tailings of initial coarseness and pre-ground tailings. A good agreement was achieved between the laboratory and experimental results. At present, the use of pre-ground tailings seems unreasonable economically, due to high costs of NaCN (0.6 kg/t vs 0.3 kg/t) and active chlorine (5.6 kg/t vs 1.2 kg/t). According to pilot tests on a flotation tailing sample weighing 67 t (with an Au content of 1.35 g/t), the gold extraction level was 31.9% at an NaCN consumption rate of 0.135 kg/t. As a result, we propose a technology of gold extraction from flotation tailings of copper-zinc ore based on the application of ultra-low concentrations of NaCN. The expected profit can amount to 1276.74 mln RUB per year, with the economic efficiency of 88% and the payback period of 1.4 years).

The possibility of hydrometallurgical treatment of old flotation tailings to extract base and noble metals was investigated. Two samples of old flotation tailings samples containing 0.26% and 0.36% of copper, and 0.22% and 0.23% of zinc were the subjects of this study. Agitation and percolator leaching was performed with distilled water and sulfuric acid solutions (of 0.5 to 10% H2SO4). It was shown that under certain conditions (sulfuric acid concentration) it was possible to achieve selective leaching of non-ferrous metals and obtain solutions with relatively low concentrations of iron ions, which is necessary for further effective extraction of non-ferrous metal ions from the solution. The effect of acid leaching on further gold recovery from the first sample containing 0.7 g/t of gold by cyanidation was investigated. The sample of the tailings after leaching with a 1% sulfuric acid solution was leached with 10% sulfuric acid. After that, the tailings sample and the acid leach residues were subjected to sorption cyanidation. Two-stage acid leaching with 1 and 10% sulfuric acid provided the higher gold recovery than one-stage (49 and 65%, respectively). Also it was shown that pregnant solution obtained during leaching of the second sample with 10% sulfuric acid may be used for oxidative leaching of substandard copper-zinc concentrate that allowed to 13 and 48% of copper and zinc from the concentrate during the leaching at 80∘C.
 Keywords: flotation tailings, leaching, substandard sulfide concentrates

By comparing a variety of programs, for the feature of a certain Cu-Pb-Zn poly-metallic sulfide ore in Yunnan, using the processes of copper and lead priority floating, combined depressants of sodium silicate + sodium sulfite + carboxymethylcellulose in copper flotation, the tailings of bulk flotation for copper and lead after activated flotation of zinc mineral by copper sulfate, the successful implementation of effective separation of copper and lead and gained a better indicator of dressing.

Insights into the design of polymetallic ore flotation circuits, including tailing desulfurization

The study covers scandium adsorption in batch conditions by VSK, DAS and PFT activated carbon grades (Russia) of different origin (сoconut shell, аnthracite, thermoset waste, respectively) from sulfuric acid-chloride solutions (pH = 2) simulating the composition of the underground leaching solutions of polymetallic ores. It was found that scandium adsorption by DAS and VSK carbons proceeds with the highest distribution coefficients (133 and 45.8 cm3/g, respectively). Isotherms of scandium adsorption with these carbons are linear and described by the Henry equation with constants 133 ± 21 and 46 ± 7 cm3/g, respectively. A limited solution volume method was used to obtain the integral kinetic curves of scandium adsorption. Their linearization according to the kinetic models of the pseudo-first, pseudo-second order, the Elovich model and the Weber–Morris intra-particle diffusion model indicates that the kinetics of scandium adsorption with VSK carbon having a higher correlation coefficient (0.999) is described using the pseudo-second order model. Description of the kinetic data obtained during the adsorption of scandium with DAS carbon showed that for all the models used the correlation coefficient is low (<0.939), while the highest value is observed when using the intra-particle diffusion model. It was suggested that the scandium adsorption process occurs in the mixed diffusion region. The possibility of scandium elution from VSK and DAS carbons with sodium carbonate solution (10 %) was studied in batch conditions, where the degree of scandium desorption in two stages of elution was 84.0 and 90.4 %, respectively.

Management of technological water at the flotation tailing dumps where tailings are deposited after the processing of polymetallic ore of copper, lead and zinc is perhaps the most important part of every polymetallic mine. Flotation processing of lead and zinc ore requires large amounts of water for flotation the lead and zinc minerals, where, after extracting the selective metal concentrates, the flotation tailings in the form of hydromix are transported to the flotation tailings dump. At the flotation tailing dump, a sand embankment is built from the sand of hydrocyclone, which limits the accumulation area of tailings, while the fine tailings particles are deposited in the accumulation area of the tailing dump, forming a beach next to the embankment and sedimentation lake. The sedimentation lake has a double function: the first is to enable the deposition of fine tailings particles with its size, and the second is to serve as an accumulation of technological water from where the water can be pumped back to the flotation plant if necessary and reused in the technological process of flotation the lead and zinc minerals.

Selection of remedial actions in tailings disposal sites based on risk assessment studies. Two case studies

Currently, the amount of waste polluting the environment, as well as the atmosphere, hydrosphere, and lithosphere, is increasing from year to year. From this point of view, the integrated use of mineral raw materials, which involves the optimal and economically feasible extraction of useful and associated minerals with minimal losses in the subsoil at all stages of the technological process, the disposal of processing waste and the implementation of environmental measures aimed at restoring ecosystems, as well as the creation of waste-free technologies are very relevant. For centuries, the best reagent for leaching gold was cyanide due to its high recovery, low cost and reliability. However, cyanide is highly toxic and causes environmental problems, which has prompted widespread research aimed at identifying and developing less toxic leaching reagents. Among the alternative leaching agents, chlorides, thiourea and thiosulfate have received the most attention. The use of thiourea as a lixiviant for gold recovery has proven more promising. This article presents the results of identifying the optimal parameters for gold extraction by leaching with thiourea from sulfide polymetallic ores of the Megradzor deposit of the Republic of Armenia. It was found that to optimize the process, it is advisable to carry out the first stage of leaching for 60 minutes, and the remaining stages for 30 minutes. In the first stage, ~ 45% of the gold is recovered, and a significant part of the thiourea is spent on dissolving other metals. The optimal conditions for the process of leaching gold with thiourea sulfate solution have been established: preliminary acid treatment of the source material, which allows removing some of the interfering impurities before the first stage and repeated use of thiourea solutions until saturation with gold. Repeating the process in 3…7 cycles makes it possible to achieve a yield of gold in solution of up to ~ 97% in a short time.

Biooxidation of arsenopyrite concentrate using BIOX® process: Industrial experience in Tamboraque, Peru

Large volumes of waste from the mining and processing industry, particularly flotation tailings of polymetallic ores, have accumulated all over the world. Mine tailings can cause severe environmental pollution and pose significant risks to both human and environmental health. However, by the contents of their metals, mine tailings can be regarded as sources for extracting copper, zinc, gold, and other metals, specifically, by using biohydrometallurgy. Stored pyritic flotation tailings of copper-zinc ores, containing 0.26% of copper, 0.22% of zinc, and 0.67 g/t of gold were studied. A continuous process of biooxidation of this waste was studied at three temperature settings of 35, 40, and 45 °C. Processing at 35 °C for 8 days caused the pyrite oxidation level to reach 73.6%, and the gold recovery by carbon-in-pulp cyanidation of the leach residue to reach 85%. The effect of pH on biooxidation of pyritic tailings at 45 °C was also studied. The pyrite oxidation level was 18% higher when the process was carried out in the pH range of 1.2–1.5, as compared to the pH range of 1.7–2.0. The results obtained are important for the development of mine waste utilization using eco-friendly biotechnology.