Chemical Selection for Flocculation of the Sludges Produced During Lime Neutralization of Acidic Spent Pickling Solutions and Rinse Water from Steel Pipe Mill

Acidic spent pickling solutions and rinse water are produced during steel pipe acid pickling. They are usually neutralised with lime in a neutralisation plant and pumped in the form of a wet sludge to a landfill. This is one of the main environmental issues of Russian steel mills. The implementation of sludge treatment units, including equipment for sludge polymer conditioning and dewatering, is an import consideration when seeking to reduce the impact of steel mills on human health and the environment. The researches results of polymer conditioning of the aggressive wastewater sludges by flocculants are reflected in the paper. Sludge samples were obtained from the neutralisation plant of an Ural’s steel pipe mill. Sludges of two types were investigated: the sludge which is formed in clarifiers during spent pickling solutions neutralization with lime and the sludge which is formed in clarifiers during rinse water neutralization with lime. During the work non-ionic, cationic, and anion flocculants Praestol® efficiency was estimated. The shortest time of water capillary suction from the flocculated sludge was accepted as efficiency criterion of flocculant processing. It was defined with use of the capillary suction timer Fann® and Whatman® 17 chromatographic paper. It is established that: non-ionic focculant Praestol® 2500 dose of 4–5 g/kg dry solids is effective for conditioning of the sludge produced during lime neutralization of acid spent pickling solutions; the anionic flocculant Praestol® 2540 dose of 1.5–2 g/kg dry solids is effective for conditioning of the sludge produced during lime neutralization of acid rinse water. The empirical response surfaces and the contour plots showing the relationship between capillary suction time and a dosage of flocculant and a charge density (% hydrolysis) of a flocculant were reveived. Keywords: steel pipe mill, acid pickling, wastewater, sludges, flocculants, capillary suction time

Theoretical Bases of Electrochemical Cleaning of Oil-contaminated Soil

This study developstheoretical bases for the electrochemical process of cleaning soils from oil, oil products and highly mineralized reservoir water. The article experimentally and theoretically reveals patterns of reducing the content of polluting oil products in soils of various types during the small voltage passing. The optimal amount of electricity for the effective removal of various types of pollution was required. For the implementation of a electrochemical soil cleaning process a scheme of an original installation with placement of electrodes in the soil was studied. It reduces the resistance between the electrodes. The technical and economical calculations to determine energy costs of the electrochemical installation for cleaning oil-contaminated soils included: the number of electrodes; the voltage depending on the properties of the soil; the area; the depth of contamination of the soil to be treated;azndthe parameters of the electrodes. This allowed us to determine and develop the required degree of cleaning. Keywords: electrochemical process, charge, soil, oil products, voltage, cleaning

Development of Technology for Processing Oil Sludge with Application of Super High Frequency Electromagnetic Fields

This article considers the problem of processing and disposing of oil sludge of various origins. Large oil companies are concerned about the problem of incomplete processing of oil sludge. The most hazardous from an environmental point of view include oil sludge formed at all stages of oil production, transportation and refining. In recent years, oil-producing enterprises have introduced various technological solutions aimed at waste management into production, but there is no single method for processing oil sludge for the purpose of neutralization and disposal. All known oil sludge processing technologies by processing methods can be divided into the following groups: thermal - burning in open barns, furnaces of various types, obtaining bitumen residues; physical - burial in special cemeteries, separation in a centrifugal field, vacuum filtration and filtration under pressure; physical and chemical - the use of specially selected reagents that change the physical and chemical properties, followed by processing on special equipment; and biological - microbiological decomposition in the soil directly in storage, biothermal decomposition. Each of them, while having certain advantages, also has its drawbacks. For over 50 years, microwave heating technology has been used in industry. To present the advantages of this method, one needs to turn to the theory of microwave heating. Keywords: oil sludge, oil waste, influence of electromagnetic fields, water-in-oil emulsions

Arsenic in Chemical and Metallurgical Conversions of Copper-zinc Concentrates

Due to the deterioration of the quality of obtained sulfide-copper concentrates, arsenic circulates and accumulates in the intermediate products, which reduces the quality of the metal and associated product – sulfuric acid. A method of estimation the distribution of impurity elements can be created using the recycling of sulfide concentrates by various technologies (including autogenous smelting, matte conversion and flotation of slags). This technique is based on solving balance equations for iron, copper and arsenic with known compositions of the resulting products. The obtained data were used to assess of the extraction of arsenic into produce outputs (slag, matte, dust, etc.). In this study, the concentration of arsenic in the dust of metallurgical processes and sludge for cleaning acid solutions is confirmed. The increased temperature in the electrostatic precipitator of gas purification of autogenous processes lead to a partial transition of arsenic into the gas stream directed to the sulfuric acid production. It is possible to regulate the fraction of transition of arsenic to dust and sulfuric acid while changing the operating temperature in the electrostatic precipitator. To a lesser extent arsenic is concentrated in the tails of flotation of slag (11.7%) and metallic copper (2.9%). These data are useful for substantiating measures for the wastes recycling and improvement of the ecological environment in the enterprise operating districts. Keywords: arsenic, autogenous melting, matte conversion, slag flotation, purified gas treatment, distribution, dust, sludge

Physical and Chemical Fundamentals and Technical Solutions for Recovery of Non-ferrous and Rare Metals from Industrial Wastes

The increasing demand for zinc and a range of zinc-related metals (for example: lead; indium; tin; cadmium; and copper) in the Russian Federation cannot be satisfied by the existing production plants due to the lack of raw materials. At the same time, ferrous and non-ferrous metallurgy and the chemical industry have accumulated hundreds of millions of tons of zinc wastes (falling into the hazard categories 2 to 4), the processing of which could not only make up the raw material base, but also improve the environmental situation. In the world, over 85% of ferrous dust is recycled using the Waelz process. The Waeltz process is used for distilling separation of elements under reducing conditions. In this study, a block diagram for production of the following elements from industrial wastes is proposed: zinc, cadmium and indium in form of massive metals; zinc and indium in the form of fine powders; and clinker as a raw material for cement production. The technical and scientific details of this new process have been patented in the Russian Federation and abroad. For the first time, the following operations have been implemented with the use of large-sized Waelz kilns: vapour-oxidized Waeltz treatment of polymetallic wastes; recycling of heat from gases and solid products with generation of process fumes; and implementation of alternative flux (dolomite) and alternative fuel (petroleum coke). Keywords: Waelz process, industrial wastes, heat recycling, vapour-oxidized Waelz processing

A Study of the Potential Use of Red Mud to Obtain Compositions Based on Portland Cement

The paper deals with the problem of utilization of red mud which is a waste product from alumina production using the Bayer method. The principal possible use for the red mud of JSC “Bogoslovsky aluminum plant” (Sverdlovsk region) for the compositions based on Portland cement is shown. It was found that the mud introduction accelerates beginning of the cement paste setting and thickens the paste reducing its mobility. It is concluded that the introduction of red mud up to 30 % is justified in terms of strength indicators. The work is carried out using mathematical planning of experiments. Keywords: red mud, Portland cement, active mineral additive, composition, properties, bauxite, chemical composition, cement stone strength, mathematical planning of experiments

Features of Waste Chemical Processing Germanium Concentrates

In order to increase the extraction of germanium in the technology of production of germanium concentrates, as well as finding ways to eliminate the accumulation of toxic waste using modern techniques and equipment, the physical and chemical properties of waste chemical processing of germanium concentrates (OHGC) of two domestic enterprises were experimentally studied. The main components of OHGC are: sulphate hemihydrate CaSO4·0.5H2O and hypochlorite Ca(OCl)2 calcium. The moisture content of the sludge amounted to 30–50 %. The content of germanium in the cakes of both companies is in the range of 0.20 and 0.27 %, respectively, indicating the feasibility of recovery in the Ge. At the same time, the samples of cakes differ significantly in the content of impurities, which depends on the types of raw materials in the preparation of concentrates. Granulometric composition of cakes is characterized by high dispersion. With an average diameter of 12 μm, all particle sizes are in the range of 0.5-15 μm. The distribution of particle sizes is shifted in interval of 0–15 μm, and the area of the particles less than 3 μm is not more than 10 %. The high dispersion of the cake is reflected in the specific surface area, which is 23.7 m2/g. Thermographic study found that the heating of the sample cake is accompanied by two endothermic effects of dehydration at 110 and 145–168 ∘C calcium sulfate and hypochloride semihydrate with corresponding weight loss of 13.1 and 12.9 %. The presence of toxic impurities (arsenic, zinc and lead), as well as chlorine, presents significant challenges for the development of disposal technology with the extraction of germanium. Assuming that the undiscovered part of the germanium in the concentrate is compounds or solid solutions with silicon dioxide, an effective technology should include their reagent high temperature treatment. Keywords: waste, germanium concentrate, chemical processing, waste, physical and chemical properties

Possibility of Slag Sensible Heat Recovery on Drum-like Installations

A variant of utilizing of slag physical heat in drum-like installations has been considered. A high-temperature melt is delivered to movable metal bodies. Heat is picked up from the working bodies surface and newly generated surfaces of slag due to interaction with working bodies. Surface of slag grains, as they cool down, allows to pick up heat with various energy characteristics. Keywords: smelter slags, heat content, drum-like installations, picking up and utilization of heat with various energy characteristics

The Influence of the Direction of the Channels of the Gas Swirlers on the Properties of the Flow of the Plasma Jet under Implementation Theoretical Basis and Technical Solutions for Recycling Technogenic Waste

A variant of the use of plasmatrons for the disposal of industrial waste and the organization of non-waste production is proposed in this article, which presents the design for the functioning equipment. A computer experiment was carried out to determine the parameters of the flow of the plasma jet. The results of a computer experiment are confirmed by a full-scale experiment. Conclusions and results are of practical benefit to developers and consumers of technological equipment. Keywords: plasmatron, flow, plasma, jet, temperature, velocity

Recycling of Waste Slag Upon Production of Manganese Ferroalloys

The mineral resources base of manganese ores is sufficiently large in Russia. However, their mining capacity is almost absent. This is due to the low quality of domestic manganese ores and the high content of phosphorus. To date, Russia has been obliged to import the commercial manganese ore, manganese-containing ferroalloys, metallic manganese, and manganese dioxide. To produce the high-carbon ferromanganese the composition of charge was developed. The optimum variant was that where 10–15% of manganese-containing raw materials were changed for waste slag. In this case, the phosphorus content in the high-carbon ferromanganese is lower by approximately 20 rel. % in comparison with the production of ferromanganese only from the manganese-containing raw materials. About 50–60 rel. % of manganese can be extracted from the waste slag of silicon-thermal production. To produce the hot metal, the composition of iron-bearing burden material was developed. The optimum variant was that where 100% of manganese raw materials were changed for the waste slag. In this case, upon production of hot metal, the specific consumptions of manganese raw materials and limestone were decreased by 100 and 20%, respectively. The phosphorus concentration in metal was lower by about 10 rel. % as compared to the production of hot metal only from the manganese raw materials. Up to 55% of manganese can be extracted from the waste slag of silicothermic production, which is irretrievably lost at present. Keywords: manganese ferroalloys, manganese-containing raw materials, waste slag, hot metal