Рассмотрена проблема утилизации хлоридных отходов, образующихся при получении губчатого титана из ильменитовых концентратов в процессе Кроля и металлического магния электролизом из природного карналлита. Техногенные хлорсодержащие отходы представляют значительную опасность для окружающей среды, загрязняя почвы и природные воды при выбросах их в атмосферу, при сбросе образующихся кислых промышленных сточных вод в водные объекты, при размещении твердых отходов в шламохранилищах. Хлоридные отходы титанового производства являются эффективными добавками в буровые растворы, улучшающие различные структурномеханические свойства последних. Предложен способ обезвреживания хлорсодержащих отходов путем перевода в водонерастворимую малотоксичную форму нейтрализацией кислых пульп известковым молоком. С хлоридными отходами теряются калий, магний, ниобий, тантал, скандий, марганец, хром и другие ценные металлы. В отходах титаномагниевого производства содержатся также рубидий и цезий, распределение которых по промпродуктам и отходам недостаточно изучено. Представлен обзор экологически безопасных, экономически оправданных технологий по переработке хлоридных отходов, который показал возможность извлечения скандия, ниобия и редкоземельных элементов и возврат в производство титана и магния. В связи с истощением минеральных сырьевых источников редких металлов переработка техногенных отходов является актуальной и перспективной.
The article presents the study results for alkaline leaching of fine ilmenite concentrate dusts from electric smelting. The physical and chemical properties of the dusts were studied using chemical and instrumental analysis methods. The dust composition was determined, X-ray phase analysis showed that the dust sample substance is in the X-ray amorphous state, iron is present in the trivalent state, and silicon is bound to magnesium. The dust sample study using a scanning electron microscope showed that part of the titanium is bound in a hard-to-disclose anasovite encapsulated in amorphous silicon oxide. The leaching study of electric smelting dust with sodium hydroxide solutions included the study of the effect of sodium hydroxide concentration, process duration, temperature, S: L ratio. The optimal conditions for dust leaching from electric smelting of ilmenite concentrate have been established: temperature 80-90 °C, duration 90-120 min, ratio S: L = 1: 5, the concentration of sodium hydroxide solution 110-115 g/dm3. The silicon extraction degree into the solution under these conditions was 77.7%. The behavior of accompanying components of chromium, zinc, iron, and manganese during dust leaching was also studied. X-ray phase analysis of the cake after leaching shows almost complete amorphization of the leached product, the main phase is a solid solution of Fe2O3·TiO2.
The article presents the results of research on the processing of such wastes of titanium-magnesium production as sludge from sludge dumps and fine dump dusts from the electric smelting of ilmenite concentrates. The results of nitric acid leaching of sludge with the transfer of calcium into solution and the production of calcium nitrate are given. Titanium-containing cake after nitric acid leaching of sludge and electric smelting dust cannot be returned to the technological process due to its high silica content, so the silicon impurity was removed from their composition. Silicon removal was performed by fluoroammonium processing with sublimation of hexafluorosilicate compounds. An amorphous silicon dioxide product was obtained, after ammonia hydrolysis of silicon-containing sublimations and appropriate treatment of the sediment. The residue from the sublimation of silicon fluorides consists mainly of titanium-containing phases and can be suitable for return for electrofusion after ammonia treatment.
Prolonged development of ore deposits, ore beneficiation and metallurgical smelting of concentrates result in the accumulation of wastes, forming large-scale dumps and sludge ponds negatively affecting the environment and human health. The creation and introduction of industrial waste treatment technologies will make it possible to dispose of them with the production of valuable commercial products and improve the environmental situation. In a research article on chemical beneficiation with the subsequent gravitational beneficiation of chrome-containing slurry tailings of Donskoy Ore-Mining and Beneficiation Plant (DOMBP), which processes chrome ore of the Kempirsay deposit in the Republic of Kazakhstan, Aktobe region, having considerable stocks of such waste is presented. The chromium-containing slurry tailings were heat-treated at 1100 °C, sintered with ammonium sulfate, water and sulfuric acid in a defined ratio at 300 °C, and then the resulting sinter was leached with water at 90 °C. The cake was washed to separate the liquid part from the solid part. The solid precipitate is the chromium-containing cake, which is upgraded by gravity concentration to a grade concentrate for ferroalloy production. When the solution is evaporated, magnesium sulfate with ammonium sulfate forms the Tutton’s salt ammoshenite. High-throughput chromium oxide extraction of 93.9% was achieved as a result of the research, and three products were obtained: (1) standard chromium concentrate with 49.48% Cr2O3 content, (2) ammoshenite used as a nitrogen–magnesium fertilizer and (3) forsterite, which is concentrated in gravity concentration tailings and can be used in the production of refractory minerals.
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