Smelting options for carbon ferrochrome based on ore raw materials, middlings and their technological evaluation

The article presents the results of large-scale laboratory tests carried out in the conditions of the Chemical and Metallurgical Institute named after V.I. Zh. Abishev on the use of briquetted mono-charge in the smelting of carbon ferrochrome on a 250 kVA furnace. The purpose of these studies was to determine the technological parameters of the use of briquetted mono-charge containing in its composition chrome ore, wastes from the production of high-carbon ferrochrome, middlings and various carbonaceous reducing agents. The main idea of using these briquettes was to multiply the contact surface of the reductant and ore, which should speed up the technological process. The principal possibility of smelting a standard alloy using briquetted mono-charge is shown. The alloy for individual charge options meets the requirements of the standards. In comparison with the technology without the use of briquettes, the mono-charge technology has shown advantages in all main parameters. The technology with the use of briquettes from the dust of the AktZF gas cleaning system is distinguished by a low yield of non-standard metal and slag, the bulk of the material goes into the gas collection system. Technologies from briquettes from fines pellet production area of Donskoy ore mining and processing plant and flash have very low specific technical and economic indicators and cannot be recommended for industrial use. Improvement of briquetting modes and technology of their smelting is required. The technical and economic indicators were higher than the current one, showed briquettes from ore and coke of the People's Republic of China, briquettes of ore from borlin and shubarkol coals of Kazakhstan.

Design and experimental tests of an Imbert type downdraft gasifier prototype and clean-up system for small-scale biomass-based power generation

This paper addresses the design, development and experimental tests of a prototype of fuel gas generation system based on biomass gasification for small-scale applications, around 5 kW. It comprises the small scale downdraft gasifier and the gas cleaning system aiming to clean-up the producer gas to be used in the upstream Internal Combustion Engine (ICE). The design of the downdraft gasifier prototype follows the methodologies that have been reported on the available literature. However, since these methodologies apply to gasifiers with larger rated powers, the adopted methodology is based on the extrapolation of the main parameters used for larger gasifiers design. For runing the ICE the producer gas requires to have a specific gas composition with an acceptable range of impurities. Therefore, a clean-up system was proposed following three stages: in first instance a hot gas clean-up using a cyclone designed to eliminate particles and compounds; then a heat exchanger was used for cooling the gas to condensate tars and water; finally a cold gas clean-up is performed by filtration using two filter steps: the first one using organic material (biomass) and the second one using a polypropylene cartridge filter. Experimental tests were performed using the developed imbert downdraft gasifier prototype, using pellets as feedstock. The preliminary results allow verifying several drawbacks that will difficult an effective integration of the developed prototype for small scale power generation applications based on ICE using low density feedstock.

Experimental study on the washing characteristics of fly ash from municipal solid waste incineration

The disposal of fly ash with high salt content has become an important bottleneck for the further application of municipal solid waste incineration (MSWI). In this study, the soluble salt content and composition of fly ash from different MSWI were analysed. The composition of fly ash was affected by incinerator type and flue gas cleaning system, especially the type of deacidification solvent. The soluble salt content in fly ash from MSW grate incinerator can be over 35.16%. Most of the soluble salt was calcium salt and chloride salt. The effect of washing parameters including liquid/solid (L/S) ratio and washing time on salt removal from fly ash were studied. Raw fly ash contained high chlorine (Cl) with the maximum of 19.83% and it can be significantly reduced by washing. Double-washing and secondary-washing had better performance than single-washing on salt removal. The secondary-washing did not only save water, but also reduced the energy cost during evaporation for crystallising soluble salt. Based on the analysis of variance (ANOVA), L/S ratio was the most principal factor for salt and Cl removal of fly ash by washing.

The Numerical Modeling of Gas Movement in a Single Inlet New Generation Multi-Channel Cyclone Separator

The work of traditional cyclones is based on the separation of solid particles using only the centrifugal forces. Therefore, they do not demonstrate high gas-cleaning efficiency, particularly in the cases where gas flows are polluted with fine solid particles (about 20 µm in diameter). The key feature of a new-generation multi-channel cyclone separator’s structure is that its symmetrical upgraded curved elements, with openings cut with their plates bent outwards, make channels for the continuous movement of the gas flows from the inflow opening to the central axis. The smoke flue of the vertical gas outflow is located near the cover of the separating chamber. The present work is aimed at studying the applicability of two various viscosity models and their modified versions to simulate aerodynamic processes in an innovative design for a multi-channel cyclone separator with a single inflow, using the computational fluid dynamics. The research results obtained in the numerical simulation are compared to the experimental results obtained using a physical model. The main purpose of this study is to provide information on how the new design for the multi-channel cyclone affects the distribution of gas flow in the cyclone’s channels. The modified viscosity models, k-ε and k-ω, and computational meshes with various levels of detailed elaboration were analyzed. The developed numerical models of a single-inlet multi-channel cyclone separator allow the researchers to describe its advantages and possible methods of improving its new structure. The developed models can be used for simulating the fluid cleaning phenomenon in the improved fourth-channel cyclone separator and to optimize the whole research process.

In Situ Catalytic Methanation of Real Steelworks Gases

The by-product gases from the blast furnace and converter of an integrated steelworks highly contribute to today’s global CO2 emissions. Therefore, the steel industry is working on solutions to utilise these gases as a carbon source for product synthesis in order to reduce the amount of CO2 that is released into the environment. One possibility is the conversion of CO2 and CO to synthetic natural gas through methanation. This process is currently extensively researched, as the synthetic natural gas can be directly utilised in the integrated steelworks again, substituting for natural gas. This work addresses the in situ methanation of real steelworks gases in a lab-scaled, three-stage reactor setup, whereby the by-product gases are directly bottled at an integrated steel plant during normal operation, and are not further treated, i.e., by a CO2 separation step. Therefore, high shares of nitrogen are present in the feed gas for the methanation. Furthermore, due to the catalyst poisons present in the only pre-cleaned steelworks gases, an additional gas-cleaning step based on CuO-coated activated carbon is implemented to prevent an instant catalyst deactivation. Results show that, with the filter included, the steady state methanation of real blast furnace and converter gases can be performed without any noticeable deactivation in the catalyst performance.

Reduction o Air Pollution from Fine Dust by Increasing Efficiency of Gas Emission Purification Sintering Furnaces

The installation of an additional stage of the "wet" waste gas purification unit at the alumina sintering furnaces ensured the achievement of a high degree of purification of gas emissions from fine impurities up to 96 % and the standards of maximum permissible emissions of solid pollutants into the atmosphere established for an industrial enterprise. The formed slude after gas cleaning is proposed to be sent for further processing to the hydrochemistry workshop, thereby ensuring its disposal without contamination of the natural environment. The analysis of air pollution indicators confirmed a decrease in emissions of solid pollutants in the atmospheric air of Achinsk.

INFLUENCE OF STORAGE TIMES OF SLUDGE FROM THE FERROALLOY INDUSTRY ON THE PROPERTIES OF CEMENT-BASED MIXTURES

Purpose. The transition to environmentally friendly, waste-free technologies is a priority for most countries in the world. The metallurgical and construction industries make a significant contribution to the formation of large volumes of man-made waste. During the production of ferroalloys, waste is generated in the form of sludge, which is stored in sludge collectors. Sludge storage has been going on for over 25 years. In order to study the effect of the duration of storage of sludge on its properties in the compositions of dry building mixtures on a cement basis, a comparison was made of the efficiency of using sludge with different storage periods. The influence of sludge of various storage periods on the strength of dry construction is estimated. Methodology. The studies were carried out in accordance with the standard methods for determining the physical and mechanical properties of solutions from dry mixtures for the installation of self-leveling floors, specified in DSTU B V. 2.7-126: 2011 “Sludge awesome dry modified. General technical minds”. Sludge from wet gas cleaning of ferrosilicon production is stored in dumps where it is a mixture of lumps of various fractions 5…50 mm in size. To use sludge in the composition of dry building mixtures, it must be dried and crushed on a roller crusher and on a disintegrator. Findings. The best ratio of the "age" of the sludge and its percentage in the composition of the mixture was determined to increase the strength characteristics of the cement stone. Originality. The influence of the chemical nature of sludge from wet gas purifiers of ferrosilicon production on the hydration processes and strength of cement stone is analyzed. Practical value. The use of man-made waste in the formulations of dry building mixtures helps to simultaneously reduce the harmful effect on the environment of industrial enterprises and increase the mechanical and economic characteristics of cement mortars based on dry mixtures.

The question of determining installation sites for the Air purification of pig premises local system elements

The allocation of intake air stream in pig premises is not evenly. The existence of engineer-ing networks and equipment, the breaching of montage technologies of air ventilation, incorrect maintenance of air ventilation system – all these factors bring to many breaches and problems. This problem such as air exchange violation in all premises, appearing zones of stasis (aero stasis), and others. As a result of which the differential of temperature and humidity has appeared. These also appear excess maximum per-mitted concentration of dust and gases. The all-exchanged ven-tilation system can’t solve all problems in local zones in pig premises. In this local air-ventilation system become more demand. For effective work of local air ventilation, the question of deter-mining installation sites for the air purification of pig premises local system elements should be solved. Keywords: LOCAL VENTILATION, AIR CLEANING FROM DUST, DUST RELEASE, HARMFUL GAS CLEANING

Exergy Analysis of Coal-Based Series Polygeneration Systems for Methanol and Electricity Co-Production

This paper quantifies the exergy losses of coal-based series polygeneration systems and evaluates the potential efficiency improvements that can be realized by applying advanced technologies for gasification, methanol synthesis, and combined cycle power generation. Exergy analysis identified exergy losses and their associated causes from chemical and physical processes. A new indicator was defined to evaluate the potential gain from minimizing exergy losses caused by physical processes—the degree of perfection of the system’s thermodynamic performance. The influences of a variety of advanced technical solutions on exergy improvement were analyzed and compared. It was found that the overall exergy loss of a series polygeneration system can be reduced significantly, from 57.4% to 48.9%, by applying all the advanced technologies selected. For gasification, four advanced technologies were evaluated, and the largest reduction in exergy loss (about 2.5 percentage points) was contributed by hot gas cleaning, followed by ion transport membrane technology (1.5 percentage points), slurry pre-heating (0.91 percentage points), and syngas heat recovery (0.6 percentage points). For methanol synthesis, partial shift technology reduced the overall exergy loss by about 1.4 percentage points. For power generation, using a G-class gas turbine decreased the overall exergy loss by about 1.6 percentage points.