Harmful Impurities Research Articles

Insights into turbulent airflow structures in blind headings under different ventilation duct distances

The paper explores the 3D stationary vortex structure of turbulent airflow near the dead-end face of a blind heading, ventilated via a forcing ventilation system. Despite its significance in blind heading ventilation, previous studies primarily focused on temporal dynamics of harmful impurities, overlooking flow structure details crucial for mass transfer processes. Our study delves into the ventilation flow structure across diverse parameters of the auxiliary ventilation system. Alongside standard flow visualization tools, we introduce three dimensionless indicators to comprehensively characterize flow structure, facilitating analysis of its variations with parameter changes and quantitative evaluation of system efficiency. Analysis revealed the formation of a single large-scale vortex within the entire range of considered ventilation system parameters in the heading. This vortex induces a significant increase in air circulation, approximately 2.5–3.5 times greater than airflow emerging from the ventilation duct’s end, thus intensifying mass transfer processes within the heading. We found that ventilation efficiency of the dead-end face zone in a blind heading with a 29.2 m² cross-section decreases linearly with increasing distance between the ventilation duct’s end and the dead-end face. However, compensating for this distance by increasing duct velocity is feasible, bearing significant implications for mine ventilation safety, particularly in ventilating blind headings with distant ducts from the dead-end face.

CFD Simulation of the Influence of the Type of Gas Distribution in the Burners on Thermal Aerodynamic Processes in the DKVR 10-13 Boiler

Topics related to fuel combustion and its impact on the environment will never lose their relevance, as the issues of efficient combustion and emission reduction are key in power generation and environmental protection. The countries of the European Union are massively abandoning the use of natural gas as a fuel for thermal power stations. However, in Asian countries, the ease of using natural gas as the main fuel and its environmental friendliness compared to coal made it possible to widely use natural gas in industry and energy sector. Comparing natural gas with alternative combustible gases (generator, blast furnace, mine, biogas), the main conclusion that it has the most attractive characteristics for its use in industry, including energy facilities, can be drawn. Therefore, it is impossible to replace it with alternative fuels in the chemical, heavy industry and energy sector in the near future. The paper is devoted to CFD modeling of stabilized combustion without premixing in a burner with low swirl for two operating modes of the boiler unit - nominal one and at 60% capacity. The study was carried out using numerical methods with the ANSYS-Fluent application program package. The object of the study is a burner built according to the technology based on the use of jet-niche systems with gas distribution of fuel by circular jets fed perpendicularly into the flow of the oxidizer through a single-row system of holes. Hydrodynamics and heat exchange processes were chosen as the subject of research, based on the analysis of which a model of NOx generation in jet-niche systems was obtained. The authors of the paper believe that replacing the regular burners of the DKVR-10-13 water heating boiler with a jet-niche ones can contribute to better mixing of fuel and air and ensure more complete combustion. In this paper, two types of burners are considered. In one of the burners, fuel is supplied through rectangular slits, in the other – through round holes arranged in a row. Air is supplied to both burners through rectangular slits. It was determined that gas distribution through round holes increases the spraying of the mixture and increases the area of combustion products spraying. Visualization of the distribution of pressure, temperature, kinetic energy profiles of turbulent pulsations and vorticity was carried out. The obtained results indicate that there are no changes in the flow regime, flame displacement or its instability. It was determined that both the axial velocity and the tangential velocity of the flow affect the distribution of combustion products and harmful impurities such as NOx. Gas distribution in circular jets stabilizes combustion and reduces flame expansion.

Modeling of thermo-aerodynamic and environmental parameters on the example of a two-pipe water heating boiler that has worked out the park resource

Topics related to fuel combustion and its impact on the environment will never lose their relevance, as the issues of efficient combustion and emission reduction are key in power generation and environmental protection. The countries of the European Union are massively abandoning the use of natural gas as a fuel for thermal power station. However, in Asian countries, the ease of using natural gas in industry as the main fuel, its environmental friendliness compared to coal, made it possible to widely use natural gas in industry and energy. Comparing natural gas with alternative combustible gases (generator, blast furnace, mine, biogas), the main conclusion can be drawn that it has the most attractive characteristics for its use in industry, including energy. Therefore, it is impossible to replace it with alternative fuels in the chemical, heavy industry and energy industry in the near future. The presented work is devoted to CFD modeling of stabilized combustion without premixing in a burner with low swirl for two operating modes of the boiler unit - nominal and at 60% capacity. The study was carried out using numerical methods using the ANSYS-Fluent application program package. The object of the study is a burner built according to the technology based on the use of jet-niche systems with gas distribution of fuel by circular jets fed perpendicularly into the flow of the oxidizer through a single- row system of holes. Hydrodynamics and heat exchange processes were chosen as the subject of research, based on the analysis of which a model of NO x generation in SNS was obtained. In this work, two types of burners are considered. In one of the burners, fuel is supplied through rectangular slits, in the other – through round holes arranged in a row. Air is supplied to both burners through rectangular slits. It was determined that gas distribution through round holes increases the spraying of the mixture and increases the area of spraying of combustion products. Visualization of the distribution of pressure, temperature, kinetic energy profiles of turbulent pulsations and vorticity was carried out. The obtained results indicate that there are no changes in the flow regime, flame displacement or its instability. It was determined that both the axial velocity and the tangential velocity of the flow affect the distribution of combustion products and harmful impurities such as NO x . Gas distribution in circular jets stabilizes combustion and reduces flame expansion.

Simultaneous precipitation removal of fluoride ion and chloride ion from smelting waste acid using renewable remover

Purification and reuse is a potential method of smelting waste acid disposal. High concentrations of fluoride and chloride in waste acid are harmful impurity and must be removed. Previous studies have shown that fluoride removal with rare earth and chloride removal with bismuth have similar cyclic process of "precipitation removal-agent regeneration" and similar reaction conditions. In this paper, a method of simultaneous precipitation removal of F− and Cl− from waste acid using La(OH)3 and Bi2O3 as a mixed remover was proposed, and the mixed remover is regenerated by sodium hydroxide solution for the recycling of the remover. Thermodynamic analysis of La3+-Bi3+-F−-Cl−-H2O system verified the feasibility of simultaneous removal. The experimental results showed that under the optimum reaction conditions, the removal efficiencies of F− and Cl− were 93.67 % and 96.47 %, respectively, and the concentrations of F− and Cl− in the solution after removal were 66.70 mg/L and 71.10 mg/L, respectively. Under the optimum conditions, the regeneration efficiencies of La(OH)3 and Bi2O3 were 96.80 % and 96.95 %, respectively. The proposed process has the advantages of no waste output, short process, and low energy consumption and provides an environmentally friendly method of removing fluoride and chloride from waste acid.

Experimental studies of bearing capacity of pipe steel of sewage systems

The results of experimental studies on the kinetics of crack growth, its relationship with the parameters of crack resistance and long-term strength of pipe steels of different service life and their structural and phase composition are presented. It was found that the value of the critical stress SK for all test steels increases with the increase in the service life, and the impact viscosity decreases, which indicates the structural embrittlement of the pipe steels associated with their sudden flooding. It is shown that the new 06G2BA steel, which is economically modified with a carbide-forming element (vanadium) and has a fine-grained structure and a low content of harmful impurities (sulfur, phosphorus), has the highest visco-plastic properties and resistance to brittle fracture. The microstrain of the α-Fe crystal lattice, as well as the quantitative decay of cementite and the redistribution of carbon between ferrite and pearlite, were evaluated by X-ray structural methods. 06G2BA steel is recommended for use in the construction of pipelines and, for example, bridge structures, which are constantly under cyclic loads with simultaneous contact with a corrosive-aggressive environment. The influence of the service life of water pipes on the hydrogen content and microcracks in pipe steels was determined. A diagram of the relationship between long-term and static strength depending on the hydrogen content in steels is recommended, which can be used by designers to rationally choose the type of steels with high crack resistance in aggressive technological environments. In order to extend the service life of pipe structures, it is necessary to use economically modified steels.

Ways to Improve Environmental Safety when Placing Alumina Production Wastes in Sludge Storage Facility

The possible scale and degree of contamination of groundwater in the areas of sludge storage of alumina plants were estimated and patterns of changes in the composition of groundwater were established. The zone of intensive impact of the sludge storage on groundwater has been determined. A set of environmental measures has been developed, providing for the creation of a contouring anti-filtration curtain, pumping of contaminated groundwater by drainage wells, carbonation of sludge waters in order to reduce pH and transfer harmful impurities into insoluble compounds.

Experimental and Numerical Study of Air Flow Reversal Induced by Fire in an Inclined Mine Working

Effective fire prevention in mine workings and tunnels requires a thorough theoretical analysis of the heat and mass transfer processes within these structures. This involves using established models to calculate non-isothermal air flow dynamics in long tunnels and mine workings. While the ventilation of tunnels has been extensively studied, significant challenges persist regarding mine ventilation systems, particularly due to their complex and branched topology. This study aimed to address these challenges and gaps in mine ventilation. We designed a laboratory bench to simulate an inclined mine working with a heat source (fire) and validated a mathematical model of heat and mass transfer in such settings. Using experimental measurements, we verified the model’s accuracy. It is important to note that our experimental and theoretical analyses focused solely on the thermal effects of a fire, without considering the release of harmful impurities. Using the validated model, we conducted multiparameter simulations to identify the conditions leading to the formation of a thermal slug in an inclined mine working and the subsequent reversal of air flow. The simulation data enabled us to determine the dependency of the critical heat release rate on the aerodynamic parameters of the mine working. Additionally, we evaluated the changes in average air density within a mine working at the critical heat release rate. These findings are crucial for the further development of a network-based method to analyze air flow stability in mine ventilation networks during fires.

Slag after Smelting of Anode Mud: Role of Sulphiding Sintering

The study object was slag from the Balkhash copper smelter, obtained by re-melting anode mud containing nonferrous metals. The process flow for processing these slags includes sintering with Na2SO4, Na2CO3, and coal, followed by soda-alkaline leaching of the sinter and extraction of metals from the solution into marketable products. Since sintering is the main operation providing high selectivity, the composition of the products of this process was studied. The main transformations during sintering were determined, and the optimal parameters were identified. The structures of slags and sintered materials obtained during the experiments were studied by electron-probe microanalysis. Sintering was performed at 600–800 °C. The best results for sulphidization of slag components were obtained at 800 °C; a further increase in temperature leads to the smelting of sinter particles and slows down sulphidization. The optimal quantities of additives, based on the weight of the slag, are Na2SO4—45%, Na2CO3—15%, and reducing agent—41%, with a sintering time of 2 h. These conditions enable the sulphidization of non-ferrous metals in the slag to the entire depth of the polymetallic globules. The distinct concentration of harmful impurities (Ni, As, and Sb) was observed in the fine structure of the polymetallic globules.

Evaluation of Fe Content on the Fluidity of A356 Aluminum Alloy by New Fluidity Index

AbstractElements that are deliberately added to aluminum alloys or are incorporated into the alloy later depending on the production process affect the final product properties. In addition, liquid metal cleaning is important in minimizing undesirable elements. Considering the production process, one of the most harmful impurities that is likely to pass into the alloy via diffusion for aluminum is the element, Fe. It is known that this is due to the fact that although Fe is highly soluble in liquid aluminum and its alloys, it has very little solubility in solids. Depending on the Fe content, mechanical properties, porosity and fluidity properties are affected in aluminum alloys. In this study, stainless and carbon steel rods were dipped into the melt at 700 °C and 750 °C for 1, 2 and 5 h. Castings were performed before and after degassing. Four-channel fluidity mold with different section thickness was used in the trials. Additionally, microstructure characterization was performed under varying casting conditions. Fluidity Index was proposed which is a single value measured from all fluidity values in different sections. When the results were examined, it was determined that the diffusion material, holding time, casting temperature and liquid metal cleanliness had an effect on the fluidity. Due to the increase in diffusion time, a decrease in fluidity was observed in both carbon steel and stainless steel. It was found that fluidity was significantly reduced when using stainless steel.

The effect of various crystalline forms of HFC 134a hydrate on the growth rate and desalination efficiency

Experimental studies on the synthesis of HFC 134a hydrate in the liquid HFC 134a – water system were performed. Despite today's lack of research on the use of HFC 134a hydrate for desalination of seawater and separation of harmful impurities by HFC 134a hydrate synthesis, this method has prospects for development: HFC 134a hydrate is synthesized at relatively high temperature and low pressure; it is poorly soluble in water, which simplifies gas hydrate separation from water–salt solution; it has high volumetric storage density and relatively high thermal conductivity. In spite of its low solubility in water, HFC hydrate exhibits relatively high growth rates. The growth of various crystalline forms and the peculiarities of their occurrence in pure water, aqueous salt solution, as well as with the addition of surfactant are considered. The use of SDS increases the HFC hydrate growth rate. For the first time, it was shown that the intensive growth of HFC 134a hydrate in the form of needles throughout the entire volume of the liquid allows increasing the efficiency of desalination. It is important to consider the desalination process comprehensively, taking into account the crystal forms, crystal growth rate, crystal defects, as well as taking into account the degree of salt removal. Simultaneously with the bubble growth, a thin gas hydrate film is shown to grow on the bubble surface. A detailed consideration of the stages of such hydrate growth is provided to explain the high-speed synthesis of porous HFC hydrate due to boiling of liquid HFC and vaporization.

Enhanced densification and mechanical properties of Ta-Hf-C solid solution ceramics by WC doping

In this paper, we propose an effective method for doping WC into Ta-Hf-C ceramics to significantly enhance their densification and mechanical properties. An increasing WC doping amount from 0 to 20 at.%, enhances the densification of Ta-Hf-C ceramics from 92.4 % to 99.1 %. This is mainly due to the fact that the doping of WC effectively removes the harmful oxygen impurities from the ceramics, thereby increasing their sintering activity. Furthermore, the doping of WC plays an active role in the mechanical properties of the ceramics. The Ta-Hf-C doped with 15 at.% WC has the highest value of 36.41 GPa for nano-hardness due to the solid solution strengthening mechanism, while the highest Vickers hardness (38.75 GPa) and fracture toughness (3.76 MPa m1/2) appear in Ta-Hf-C doped with 20 at.% WC. The main toughness mechanism is W segregation at the grain boundary, enhancing grain boundary strength.

ChlorTox scale assessment, greenness, and whiteness evaluation of selective spectrophotometric analysis of dimenhydrinate and cinnarizine

Nausea and vomiting are considered common series side effects induced by chemotherapy treatment in cancer patients. This annoying side effect can impair the patient’s compliance to cancer treatment and affect their quality of life. Dimenhydrinate and cinnarizine in combined pharmaceutical dosage form is used to control chemotherapy induced nausea and vomiting in cancer patients. For safety, selective spectrophotometric methods based on novel dual resolution strategies were introduced to estimate dimenhydrinate and cinnarizine in presence of their harmful impurities namely benzophenone and 1- (diphenylmethyl)piperazine, respectively. These methods namely, dual ratio difference (DRD), dual ratio extraction (DRE) and dual absorbance extraction coupled with dual ratio extraction (DAE-DRE) were successfully performed to simultaneously analyze the drug of interests dimenhydrinate and cinnarizine in their pure form, synthetic mixtures and in market dosage form. Linearity ranges were 6.0–60.0 μg/mL and 3.0–30.0 μg/mL for dimenhydrinate and cinnarizine, respectively with good recovery% of Mean ± SD for all the proposed methods 99.82 ± 0.48, 99.79 ± 0.40, 100.14 ± 0.82, 100.03 ± 0.69, respectively. ICH guidelines were adhered in accordance with confirming validation of the proposed methods where fulfilling results were accomplished. Various unified greenness and whiteness assessment tools, such as the chlorTox scale, greenness index via spider chart, AGREE (The Analytical Greenness Metric), green certificate, and the RGB12 algorithm were employed in this research to assess the greenness and sustainability of the introduced UV-spectrophotometric methods in comparison to the reported HPLC method. As a result, these methods hold significant potential for utilization in the quality control department of pharmaceutical companies, contributing to enhanced pharmaceutical product analysis and overall sustainability practices.

Flame‐Retardant, Self‐Purging, High‐Voltage Electrolyte for Safe and Long‐Cycling Sodium Metal Batteries

AbstractSodium metal batteries (SMBs) remain greatly challenging in safety and stability. Herein, a flame‐retardant s designed, self‐purging high‐voltage electrolyte is designed to stabilize SMBs with the use of ethoxy (pentafluoro) cyclotriphosphazene (PFPN) as the electrolyte additive. PFPN can participate in the shell structure of solvation through stronger van der Waals force to form Na3N, NaF‐rich solid/cathode electrolyte interphase (SEI/CEI) with electronic insulation and fast ion transport. Moreover, harmful impurity (PF5) also can be scavenged by van der Waals force to avoid HF production, which helps to stabilize the electrode interface. Additionally, combustion radicals (H, HO) can be cleared by van der Waals force between radical (RPO) formed by breaking with PFPN and combustion radicals for flame‐retardation purpose. As expected, the high‐voltage Na||Na3V2(PO4)2O2F battery with modified electrolyte can deliver reservation of 92.4%, CE of 99.71% after 2000 cycles, and simultaneously possess excellent high‐rate and fast charging/slow discharging performance.

Plasma Processing of Rubber Powder from End-of-Life Tires: Numerical Analysis and Experiment

Tire recycling is becoming an increasingly important problem due to the growing number of end-of-life tires (ELTs). World-wide, ELTs account for more than 80 million tons. ELTs contribute to environmental pollution in the long term. They are flammable, toxic and non-biodegradable. At the same time, ELTs contain rubber, metal and textile cord, which are valuable raw materials. ELTs are buried in landfills, burned, crushed and restored. Most of these methods have a negative impact on the environment. From an environmental point of view, the most preferred ways to recycle tires are retreading and shredding. Rubber powder (RP) or crumb is mainly used for rubber pavers production, waterproofing, curbs, road slabs and various surfaces. An alternative method for RP processing, eliminating the disadvantages of the above approaches, is plasma gasification and pyrolysis. The paper presents a thermodynamic and kinetic analysis and an experiment on plasma processing of RP from worn tires to produce flammable gas. At a mass-average temperature of 1750 K, the yield of synthesis gas from plasma-air gasification of RP was 44.6% (hydrogen—19.1, carbon monoxide—25.5), and 95.6% of carbon was gasified. The experimental and calculated results satisfactorily agreed. It was found that plasma products from RP did not contain harmful impurities, either in calculations or experiments. Plasma gasification allows for recycling ELTs in an environmentally friendly way while also generating flammable gases that are valuable commodities. In this research, plasma technology was demonstrated to be effective for gasifying RP to produce flammable gas.

The durability increasing of high-wear cast parts of mining and processing equipment

The analysis of the operation of rapidly wearing parts of the ore-grinding equipment was carried out. It has been established that unloading grates and ladles are fast-wearing parts of layered fracture mills and determine their downtime between repairs. The possibility of improving the mechanical properties of medium-carbon steel 40HL due to the reduction of harmful impurities is shown. The effects of modification with aluminum, vanadium, calcium, and rare earth metals on structural formation, mechanical, and operational properties of steel are investigated. It was established that the complex modification of cast steel 40HL (0.04…0.1% vanadium, 0.15% silicon calcium and 0.15% rare earth metals) allows to significantly increase its mechanical properties and wear resistance. The separate and joint influence of aluminum, vanadium, calcium and rare metals on the austenite grain size and hardening of steel was studied. The proposed modification technology makes it possible to obtain a fine grain, through-hardening of castings and ensure reliable and long-lasting operation of ball mills.

Current collapse suppression in AlGaInN/GaN HEMTs with thin unintentionally doped GaN channel and AlN back barrier grown on single-crystal AlN substrate

A high-electron-mobility transistor (HEMT) structure consisting of a 15-nm-thick quaternary AlGaInN top barrier layer, a thin 200-nm-thick unintentionally doped (UID) GaN channel layer, and an AlN back barrier was grown on a single-crystal AlN substrate by metal–organic chemical vapor deposition. The HEMTs fabricated on the grown heterostructure exhibited DC pinch-off characteristics with no large negative resistance owing to the high thermal conductivity of the AlN substrate. The 2-μm-gate-length devices showed the maximum current density of 500 mA/mm and the peak transconductance of 120 mS/mm with the threshold voltage of approximately −4 V. The off-state leakage was less than 30 μA/mm thanks to the thin UID-GaN channel with good crystal quality. The pulsed I–V characteristics for the fabricated HEMTs showed much smaller drain current decreasing compared to the same structured HEMTs with a C-doped GaN back barrier on a SiC substrate. This indicates that the UID-GaN channel grown on the AlN substrate had no harmful impurity levels that cause the current collapse phenomenon. The above-mentioned results demonstrate that the combination of the thin UID-GaN channel and the AlN back barrier works effectively in GaN HEMTs, and it will contribute to the device design and fabrication for future high-power/high-frequency applications.

Ecological modernization at construction industry enterprises as an innovative production and management technology

The article delves into the pivotal role of ecological modernization, specifically the environmentalization of production at enterprises in the building materials sector. A comprehensive study was conducted on the product range of Ivano-Frankivskcement PJSC, one of the largest enterprises in the Western region. This case study serves as a tangible example, demonstrating that the adoption of environmentally friendly production necessitates both the environmentalization of production processes and management. The implementation of a comprehensive environmentalization strategy involves the incorporation of ecologically oriented measures in both the internal and external environments of the production system, while the environmentalization of the management system entails a restructuring of organizational forms and management methods to align with ecological principles. It was established that an essential part of ecological modernization is the introduction of environmental management systems. This includes requirements for waste and its processing, control over the use of water resources, and implementation of environmental certification and standards. Ecological modernization at enterprises in the construction industry helps to reduce the sector's ecological impact on the environment, contributes to the preservation of natural resources, and improves people's quality of life. It is proposed that enterprises producing building materials switch to the use of a dry method of production - an innovative technology that will contribute to the reduction of morbidity in the population and will protect the natural environment from harmful impurities and combustion products. The main advantage of this is energy-saving and highly efficient cement production technologies. It is emphasized that when carrying out production activities, enterprises in the field of production of construction materials should also apply management technologies of controlling, outsourcing, foresight, etc., with the help of which adverse environmental and economic problems can be detected promptly, and suggestions for their elimination can be made. Keywords: ecological modernization, "green" technologies, enterprise, business entity, management, production, ecological situation.

Targeted and untargeted screening for impurities in losartan tablets marketed in Germany by means of liquid chromatography/high resolution mass spectrometry

Technical advances in the field of quality analysis allow an increasingly deeper look into the impurity profile of drugs. The ability to detect unexpected impurities in addition to known impurities ensures the supply of high-quality drugs and can prevent recalls due to the detection of harmful unexpected impurities, as has happened recently with the N-nitrosamine and azido impurities in losartan (LOS) drug products. In the present study, the LC-MS/HRMS approach described by Backer et al. was applied to an even more complex system, being the investigation of 35 LOS drug products and combination preparations purchased in 2018 and 2022 in German pharmacies. The film-coated tablets were analysed by means of four LC-MS/HRMS method variants. For the separation a Zorbax RR StableBond C18 column (3.0 ×100 mm, particle size of 3.5 µm, pore size of 80 Å), a gradient elution and for mass spectrometric detection a qTOF mass spectrometer with electrospray ionization in positive and negative mode was used. An information-dependent acquisition method was applied for the acquisition of high-resolution mass spectrometry data. The combination of an untargeted and a targeted screening approach revealed the finding of eight impurities in total. Beside the five LOS related compounds, LOS impurity F, J, K, L, M, and related compound D from amlodipine besilate, LOS azide and an unknown derivative thereof were detected. Identification and structure elucidation, respectively, were successfully performed using in silico fragmentation. Differences in the impurity profiles of drug products from 2018 and 2022 could be observed. This study shows that broad screening approaches like this are applicable to the analysis of drug products and can be an important enhancement of the quality assurance of medicinal products.

Experimental studies of the influence of hydrogen and sulfur on sulfide-corrosion destruction under tension of pipelines

For the first time, comprehensive experimental studies of the influence of hydrogen and sulfur on sulphide stress corrosion cracking (SCR) of pipe steels in a corrosive-aggressive environment of NACE were carried out. In the research, experimental steels of the 06G2BA and 08KHMCHA brands, which are widely used in the construction of pipelines for various purposes, were used an analytical system (analyzer of non-stationary processes – ANP) was developed and tested in laboratory conditions, into which the installation for tests on corrosion-mechanical cracking under stress was integrated. For the first time, comprehensive experimental studies of pipe steel samples of grades 06G2BA and 08KHMCHA under the influence of sulfur and hydrogen were carried out, which made it possible to develop an understanding of the mechanisms of SCDS (sulphide-corrosion destruction under stress) and HID (hydrogen-initiated destruction). For the first time, experimental studies of the corrosion kinetics of 06G2BA and 08KHMCHA steels were carried out depending on the duration of the tests in the NACE model environment, while three periods of the formation of corrosion products were determined. It was found that sulfur and hydrogen, which are dissolved in test pipe steels, have a strong influence on the growth rate of corrosion cracks of SCDS, which made it possible to determine the optimal content of sulfur and hydrogen in steel 06G2BA. It is shown on the basis of the results of experimental studies that to ensure high crack resistance of pipe steels under conditions of static and cyclic loads both in air and in conditions of corrosive-aggressive environments, the sulfur content should not exceed 0.015-0.020%, and the dissolved hydrogen content should not exceed 2-3 ppm . The obtained results make it possible to improve pipe steels in the process of their smelting at metallurgical enterprises thanks to the use of economical modification with niobium, chromium, cerium and other impurities, which contribute to the fragmentation of the structure and reduce the content of non-metallic inclusions and harmful impurities.

Study on Optimization of Deep Purification Process Design of Zinc Oxygen Pressure Acid Leaching Solution

According to the characteristics of high impurity content and complex composition of oxygen pressure leaching (OPL) solution of zinc sulfide concentrate, combined with the quality requirements of large plate electrowinning and automatic plate stripping, the advanced purification process of solution was designed. Through the deep purification process consisting of neutralization indium precipitation and low iron purification, high temperature antimony salt nickel and cobalt removal, copper slag chlorine removal, low temperature zinc powder replacement copper and cadmium removal, fine purification, calcium and magnesium removal, the contents of harmful impurities such as iron, indium, copper, cadmium, nickel, cobalt, fluorine and chlorine in the solution are strictly controlled to ensure that the quality of the deeply purified zinc sulfate solution is qualified and can meet the needs of continuous and stable production. The energy-saving effect of advanced purification process is obvious, and the average DC power consumption per ton of electric zinc is 2880kWh, reaching the advanced level of the same industry in China. The good effect of advanced purification process ensures the successful application of OPL and large plate zinc electrowinning, and improves the technology and equipment level of zinc smelting industry, which has important popularization and application value.