No abstract

The article presents the results for obtaining the conditioned target product from metallurgical waste, such as vanadium-containing converter slag, steelmaking slag and magnesium-containing fused periclase, by increasing their particle surface reactivity through mechanical activation at the grinding stage. The paper presents the characteristics of the feed and grinding products and the process flows for the processing of respective technogenic raw materials. The dispersion and reactivity of the finely dispersed product, established by the change in the material wetting heat, and the role of mechanical activation for the subsequent processing and improvement of the resulting product grade are evaluated. Mechanical activation of magnesium oxide powder at the last processing stage for low-grade fused periclase promotes an increase in the energy of surface-active centers of the ground material and an improvement in its electrical insulating properties (as compared with ball grinding). Mechanochemical activation of vanadium slag promotes the formation of homogeneous, well-permeable granules, intensification of redox processes during leaching and obtaining the target product (V2O5 paste) with the mass fraction of vanadium pentoxide of 84–86 %. An increase in the reactivity of the dump steelmaking slag during mechanochemical activation allows obtaining high-activity composite cements with the slag content of up to 20 wt.%.

Industrial waste waters rich in heavy metal ions and sulfates are a common phenomenon caused by oxidation of sulfide ore bodies and associated waste. Oxidized products enter a water body leading to a greater number of metal ions, a higher concentration of dissolved salts and a lower pH thus affecting the quality of water. As the environmental impact of sulfates is less detrimental than that of dissolved metals or acidity, the sulfate control has received little attention in many regulatory jurisdictions. It should be noted that the literature on sulfate removal from industrial waste waters is relatively sparse. However, a number of techniques are available to lower the concentration of dissolved ions, including sulfate ions. The sulfate control levels are based on the maximum permissible concentration (MPC) of approximately 100 mg/l for fisheries and on the secondary drinking water recommendations of approximately 500 mg/l. Methods of sulfate removal from industrial waste waters can be of two types: removal through semi-permeable membranes; removal by salt precipitation through ion exchange; permeable reactive barrier; biological recovery or insoluble mineral precipitates. This article offers an overview of the main sulfate removal options for industrial waste waters, as well as a feasibility study comparing the available techniques. The feasibility study suggests that among the techniques available today, biological methods and methods involving chemical reagents offer the most advanced options. An effective lowcost pre-treatment option for sulfates includes lime treatment, which is relevant if the sulfate concentration exceeds 2,000 mg/l. The most suitable option for sulfate removal will be dictated by site-specific conditions of a particular mining operation.

Аннотация. Тонкодисперсные шламы сооружений очистки отходящих газов и сточных вод горно-металлургических предприятий, с одной стороны, являются экологически опасными отходами, с другой -техногенным ресурсом металлов. В статье рассмотрены состав, структура, физические и химические свойства шламов предприятий черной и цветной металлургии. Шламы разделены авторами на две группы по обособленности фазы, содержащей ценный компонент, от других ингредиентов шлама. Такое разделение является важным для оценки пригодности шламов для разделительных процессов обогащения и выбора решений по подготовке данного вида тонкодисперсного техногенного сырья и его вовлечения в переработку с извлечением металлов. Описана современная практика утилизации шламов на предприятиях. Проанализированы существующие и предложены новые технологические решения, позволяющие вовлечь шламы в рециклинг металлов. Отмечено, что в некоторых случаях для эффективной утилизации шламов необходимо целенаправленное получение в многостадиальном процессе очистки вод селективных по металлу шламов. Представлены результаты изучения конкретных представителей выделенных групп шламов, результаты лабораторных испытаний по извлечению из них цветных металлов. Описаны разработанные технологические решения по комплексной переработке железоцинксодержащих доменных шламов ОАО «Магнитогорский металлургический комбинат» по комбинированной схеме, включающей обратную флотацию шламов и мокрую магнитную сепарацию. Представлены результаты использования, контролируемого по рН гидроксидного и сульфидного осаждения, а также схемы цементация-сульфидное осаждение для получения селективных медь-и цинксодержащих шламов при переработке подотвальной воды. Приведены технологические и экономические показатели переработки. Сформулированы принципы, на которых должны базироваться технологические решения ресурсосберегающих технологий переработки шламов.

An analysis was made of the use of magnesium-containing materials of natural and technogenic origin in complex systems for the purification of wastewater from mining enterprises from heavy metals. The transfer mechanisms of dissolved heavy metals into the precipitate and onto the surface of the sorbent have been theoretically studied. Magnesium-containing minerals in water partially undergo hydration, forming an association of complex molecules. The main purification mechanism is the formation of sparingly soluble metal hydroxides. The mechanisms of adsorption, co-precipitation, co-crystallization of impurities with products of hydration and hydrolysis of magnesium-containing minerals also work. Exploratory studies of the intensification of the wastewater treatment process using magnesium-containing materials have been carried out, which have shown that the residual concentration of almost all metals, with the exception of nickel and chromium, when using brucite at the same pH level is lower. The highest water purification efficiency is observed for zinc and lead ions. The addition of dolomite to brucite in an amount of less than 10% makes it possible to reduce the residual concentration of cadmium in water at 20-60 minutes of contact and other equal experimental conditions.