Stainless Steel Scrap Research Articles

Valorization From Waste: Combined Reduction of Chromite Ore Processing Tailing and Sub-Grade Manganese Ore to Produce 200 Series Stainless Steel Scrap

Valorization From Waste: Combined Reduction of Chromite Ore Processing Tailing and Sub-Grade Manganese Ore to Produce 200 Series Stainless Steel Scrap

Microstructure and corrosion investigation of FeCoCrNiMo0,5(MnAl)0,3 high entropy alloy produced by 316 L stainless steel scrap

FeCrCoNiMo 0,5 (MnAl) 0.3 high-entropy alloy (HEA) was manufactured via arc melting process by adding the related metal powders into scrap of 316L stainless steel for corrosion resistance tests under salt and acid conditions. Cyclic potentiodynamic polarization experiments performed under acidic conditions revealed pre-passivation due to abundance of network modifying metals in HEA composition which was further analyzed by electrochemical impedance spectroscopy. Elemental resolved analysis of leftover solutions was used to compare metal ions released during corrosion. X-ray diffraction analysis indicated the phase change in heat treated HEA samples. Non-heat treated HEA samples can be compared with stainless steel under moderate corrosion conditions and had better hardness results.

Heat Treatment of Recycled Battlefield Stainless-Steel Scrap for Cold Spray Applications

This work explores the impact of thermally preprocessing recycled austenitic stainless-steel powder for solid-state cold spray metal additive manufacturing with a focus on increasing deposition quality and coating density while maintaining mechanical integrity. The recycled stainless-steel scrap was gas-atomized using a novel mobile foundry manufactured by MolyWorks Materials Corporation. The powder was thermally treated based upon thermodynamic modeling using Thermo-Calc. The powder and sprayed specimens were characterized using particle size–shape analysis, microscopy, x-ray diffraction, and nanoindentation. Diffraction results highlighted the presence of both austenite and ferrite phases in the powder. Nanoindentation confirmed that thermally processing the feedstock powder at the austenitization temperature decreased the amount of ferrite present, which was consistent with the porosity observed in the deposits due to the lower yield strength of austenite relative to ferrite. The untreated powder deposits exhibited extensive porosity and microcracking, as opposed to the virtually fully dense deposit from the heat-treated powder.

Mechanical behaviour of self compacting concrete with hybrid fibres

Research lag on the stainless steel scrap (lathe waste) on the mechanical behaviour of self-compacting concrete was inferred. It is proposed to investigate the mechanical and flexural behaviour of self-compacting concrete completely under IS-10262:2019 (chapter 7: SCC). Here the effective utilization of materials namely steel fibre and lathe waste as an additive, cement is to be partially replaced with Ground Granulated Blast Furnace Slag (GGBS) along with High Range Water Reducers (ether-based superplasticizer) are to be compared with the control specimen of SCC. Adding fibre content to the volume of concrete by replacing 0%, 0.5%, 1.0%, 1.5% and 2.0% of steel fibre and constant replacing of 0.125% of stainless steel scrap with steel fibre and proceeds as a hybrid combination in SCC.

Casting and Laser Surface Melting of 316L Stainless Steel from Scrap Resources

316L stainless steel is used in various industrial applications including chemical, biomedical and mechanical industries due to its good mechanical properties and corrosion resistance. Recycling of 316L stainless steel scrap without significantly reducing its value has received recently great attention because of the environmental regulations. In the current work, 316L stainless steel scrap was recycled via casting using Skull induction melting technique. The casted products subsequently subjected to laser surface melting process to improve its surface properties to be used for harsh environment. The results showed defect free surfaces with homogeneous microstructures. Nano size grains were also obtained due to rapid solidification process. Such nano size grains are preferred for extending the usage of the 316L stainless steel in new applications.Corresponding author: E-Mail: elgazzar.ha@gmail.com

Three-dimensional batch electrochemical coagulation (ECC) of health care facility wastewater-clean water reclamation.

Three-dimensional (3D) batch ECC of raw health care facility wastewater (HCFWW) was adopted using stainless steel (SS) and aluminum (Al) scrap metal particle electrodes. ECC treatment was focused on priority quality parameters viz., chemical oxygen demand (COD), color, and other important water quality parameters. Sludge settling and filterability for post-ECC slurry were investigated after ECC. COD removals of 87.56 and 87.2% were achieved for current densities (CD) 83.33 and 125A/m2 using SS-3D electrodes, and similarly, 86.99 and 86.23% COD removal for Al-3D electrodes. Simultaneously, color removals were 88.50 and 87.60% for CD 166.66A/m2 (4A) using SS and Al-3D electrodes. Water quality parameters viz., nitrate, phosphates, and sulfate were also removed by 93.18%, 96.83%, and 41.07% for SS-3D electrodes, while Al-3D electrodes showed 93.15%, 96.72%, and 25.94% removal. Post-ECC slurry settling was good for all the applied CD using SS-3D electrodes generating dense and sturdy flocs. Al-3D electrodes showed excellent floc settling properties. SS-3D electrode flocs displayed good filterability at 1A with α: 2.497 × 1011mkg-1 and Rm 1.946 × 1010m-1. Post-ECC slurry using Al-3D electrodes were viscous causing delayed filterability giving α: 1.1760 × 1011mkg-1 and Rm1.504 × 109m-1 for 3A. E. coli was destroyed by 97 and 98% for 2A and 3A respectively. Clear water reclamation of 85-90% and pollutants/contaminants removed within a short HRT of 75min proved the effectiveness of adopting 3D-ECC for treating raw HCFWW.

Comparative Energy, Resource and Recycling Lifecycle Analysis of the Industrial Repair Process of Gas Turbine Burners Using Conventional Machining and Additive Manufacturing

SummaryLaser beam melting (LBM), also known as selective laser melting, is a powder bed fusion type of additive manufacturing (AM) technology used to fabricate metal parts from metal powder. LBM is a promising technology that offers new opportunities for increasing resource efficiency. The aim of this study was to compare environmental impacts of conventional manufacturing methods with AM for a real industrial application. Analysis was performed on the repair process of a burner used in a Siemens industrial gas turbine. The results of this study show that the repair process based on AM provides significant reduction in material footprint (abiotic depletion potential), primary energy consumption, and carbon footprint compared to conventional machining and welding processes. Even though the AM process has increased power and inert gas consumption on the shop floor, the complete life cycle shows that the conventional processes have a much higher environmental footprint from material use upstream. Different recycling models of nickel‐based alloy and stainless steel scrap strongly influence the cradle‐to‐gate life cycle footprint. The results show that an AM process can have a sustainability advantage if it is designed in a holistic cradle‐to‐gate approach. The study also shows potentials for the LBM machine developers for entry into the industrialization of AM. Energy reduction potentials were identified during the idle mode, during operation mode from the supply of cooling duty, and also related to inert gas consumption. Careful consideration of these potentials can further improve the primary energy footprint of the LBM process.

Characterization and Sulfuric Acid Leaching of Ferrochrome Converter (CRC) Dust

A ferrochrome converter (CRC) is used for removal of silicon and carbon from ferrochrome in stainless steel production. The raw materials are molten ferrochrome and stainless steel scrap, and the process produces a raw material for argon-oxygen-decarburization (AOD). The zinc content prevents the utilization of CRC dust (CRCD). The objective of this work is characterization and sulfuric acid leaching of CRCD and evaluation of formation mechanisms and the effects of mineralogy and microstructure on the hydrometallurgical treatment. CRCD contains critical (Cr, fluorite) and economically important (Fe, Zn) materials. The mineralogy and microstructure of CRCD are complex. The dust has been formed by many mechanisms. Lime and ferrosilicon prove that take-off of solid particles during charging is important. Also, ejection of liquid droplets is considerable because ferrochrome and slag spheres are common. The highest Zn dissolution is 93–94% and at the same time 5–15% of Cr is leached. The existence of zincite explains the high dissolution of zinc. The encapsulation, e.g., magnesiochromite enclosed into glass, explains the low chromium dissolution. The best selectivity for Zn extraction over iron, chromium, and nickel is achieved with 0.5 M, at 30 and 60 °C with both L:S 10 and L:S 20.

Environment Emission and Material Flow Analysis of Chromium in Korea

Abstract With the stabilization of Korea’s industrialization, it has become interested in the efficient use of rare met-als, climate change and industrial environment and safety etc. It is thus making efforts to implement economic policiesthat address such issues. Therefore it is necessary to understand the demand, supply and use of metal materials. Since2010, the Korean government has developed the integrated material flow methodology and has been trying to examinethe demand, supply and use of metal materials. In 2013, the Korean government surveyed the material flow of chro-mium. Material flow analysis and environment emission of chromium were investigated 8 steps; (1) raw material, (2)first process, (3) Intermediate product, (4) End product, (5) Use/accumulation, (6) Collection, (7) Recycling, (8) Dis-posal. Chromium was used for stainless steel, alloy steel, coated sheets, refractory material and coating materials. Recy-cling was done mainly in use of stainless steel scrap. To ensure efficient use of chromium, process improvement isrequired to reduce the scrap in the intermediate product stage. In the process of producing of the products using chro-mium, it was confirmed that chromium was exposed to the environment. It requires more attention and protectionagainst environment emission of chromium.Keywords: Chromium, Materials flow analysis, Environments emission, Recycle

Life cycle assessment of resource recovery from municipal solid waste incineration bottom ash

Bottom ash, the main solid output from municipal solid waste incineration (MSWI), has significant potential for the recovery of resources such as scrap metals and aggregates. The utilisation of these resources ideally enables natural resources to be saved. However, the quality of the recovered scrap metals may limit recycling potential, and the utilisation of aggregates may cause the release of toxic substances into the natural environment through leaching. A life cycle assessment (LCA) was applied to a full-scale MSWI bottom ash management and recovery system to identify environmental breakeven points beyond which the burdens of the recovery processes outweigh the environmental benefits from valorising metals and mineral aggregates. Experimental data for the quantity and quality of individual material fractions were used as a basis for LCA modelling. For the aggregates, three disposal routes were compared: landfilling, road sub-base and aggregate in concrete, while specific leaching data were used as the basis for evaluating toxic impacts. The recovery and recycling of aluminium, ferrous, stainless steel and copper scrap were considered, and the importance of aluminium scrap quality, choice of marginal energy technologies and substitution rates between primary and secondary aluminium, stainless steel and ferrous products, were assessed and discussed. The modelling resulted in burdens to toxic impacts associated with metal recycling and leaching from aggregates during utilisation, while large savings were obtained in terms of non-toxic impacts. However, by varying the substitution rate for aluminium recycling between 0.35 and 0.05 (on the basis of aluminium scrap and secondary aluminium alloy market value), it was found that the current recovery system might reach a breakeven point between the benefits of recycling and energy expended on sorting and upgrading the scrap.

동의 폐자원흐름분석을 통한 자원순환 활성화 방안

기존 사례조사를 바탕으로 국내의 구리에 대한 물질흐름 분석을 Up-stream과 Down-stream으로 구분하여 실시하였으며, 2010년 기준 폐기물로 배출된 이후의 폐기 재활용 흐름에 대해서 현장조사를 통한 분석을 실시하였다. 배출 이후의 물질흐름을 배출 및 수입, 수거 및 폐기, 자원회수, 제품생산 및 수출의 4단계로 나누어 각 단계별로 분석했다. 재활용 단계에서 36.8%의 자원순환율 도출 되었고, 이를 바탕으로 각 단계별로 자원순환율을 증진시킬 수 있는 여러 방안을 제시하였다. 배출 및 수입 단계에서는 지정을 세분하여 적절한 경우 이를 폐기물 자원으로 분류할 것을 제안하였다. 이런 폐자원에 대해서 할당관세를 적용을 제안하였다. 수거 및 폐기 단계에서는 부과세 편취 해결과 입찰제도의 개선을 통한 수급 안정화 방안을 제시하였다. 자원순환단계에서는 전문적인 파쇄 및 분쇄 업체를 육성방안과 대기업과 중소기업간의 상생방안을 제시하였다. 제품생산 및 수출 단계에서는 현재 구리스크랩 재활용 상황에서 재활용 활성화를 위해서 폐기물 처리시설의 등록 면제 요청하고 있으나 이보다는 폐기물 처리시설로 등록을 위해서 필요한 모든 인허가를 통합적으로 처리하는 방안을 제시하였다. The materials flow of copper can be analyzed into up-stream and down-stream stages based on the literature survey. Discharge and recycling stages in the down-stream have been particularly analyzed through the field survey. The waste nickel resources circulation flow may conveniently be grouped into 4 stages discharge import, collection disuse, resource recovery and product production export, the resources mainly consist of copper scrap and stainless steel scrap in 2010. The resource circulation rate of 36.83% is obtained from the above flow. Various plans are therefore, suggested in each stage to increase resource circulation rate. At discharge import stage, it is suggested to consider this kind of waste as an important resources if it is appropriately classified in detail, basides applying quota tariff to this kind of waste. At collection disuse stage, the plan of stabilizing supply and demand is suggested through the improvement of bidding system. Resources professional cycling stage crushing and grinding companies foster coexistence between large and small plans and strategies were suggested. At product production export stage, the integrated approval is suggested approval for licensing to register units as waste-treating facilities instead of exempting registration under the present condition to activate recycling industries.

Substance flow analysis of chromium and nickel in the material flow of stainless steel in Japan

This paper dynamically analyzes the Japanese material flow of stainless steel. The substance flow analysis of Cr and Ni associated with stainless steel was conducted by classifying the material flow of stainless steel into two main alloy types: ferritic and austenitic. The substance flow covered more than 80% of Cr and Ni consumption in Japan. In mass balances of Cr and Ni, the production of not only stainless steel but also other alloying steels containing Cr and/or Ni was taken into account. The mass balances of three elements (Fe, Cr, and Ni) provided complementary information for confirmation of our estimations. As a result of dynamic analysis, the in-use stock of ferritics and austenitics at the end of the year 2005 was 4 Tg and 14 Tg, respectively, which converts to 3 Tg of Cr and 1 Tg of Ni. In addition, the recycling flow was closely analyzed. From the result for the year 2005, the recycling rates as stainless steel scrap were estimated as 21–38% for ferritics and 94–100% for austenitics. The amount of ferritics scrap to be recycled as carbon steel was quantified as well. By comparing our results with those in previous studies, we found that applying parameters obtained in other countries may be misleading, especially in recycling flows.

Measuring the status of stainless steel use in the Japanese socio-economic system

To reduce the amount of materials that are extracted from and emitted to the environment, reutilization and long-term use within our socio-economic system are important goals. From this perspective, the average number of times a material comes into use and the total average lifetime of a material are useful indicators for measuring the status of our material use. In general, multiple uses and long lifetime indicate effective and efficient material use. In this article, we estimate these usage and lifetime indicators for stainless steel (SS) for the Japanese socio-economic system and discuss the meanings of these indicators given its main alloying elements. The following conclusions are drawn: (1) Based on Japanese SS use in 2005, SS is estimated to be used 1.9–4.3 times in average over its entire life cycle depending on possible low and high collection rate scenarios of SS obsolete scrap. SS is estimated to be used for 19–100 years in average over its entire life cycle, under the low collection rate and short product lifetime (LCR&SPL) to high collection rate and long product lifetime (HCR&LPL) scenarios. (2) Some SS scrap is used for carbon and other alloyed steels (COAS) production. Although SS scrap that is recycled within COAS cycles no longer functions as SS, iron contained in SS does serve a function in COAS products, considering an elemental interpretation. Iron contained in SS is estimated to be used 3.2–6.8 times and for 56–170 years in average over its entire life cycle, under the LCR&SPL to HCR&LPL scenarios. (3) From the viewpoint of sustainable material use, estimated total average lifetime of SS is not considered to be satisfactory. More effective and efficient material use needs to be achieved through the improvement in collection rates of obsolete scrap and lifetimes of final products.

Substance Flow and Stock of Chromium Associated with Cyclic Use of Steel in Japan

Previous studies have pointed out that some quantity of ferritic stainless steel scrap is mixed with carbon steel scrap, thus resulting in the accumulation of chromium in carbon steel products. Chromium substance flow accounts for 97% of its consumption in Japan. This paper describes the analysis chromium substance flow in stainless steel, other alloy steels, and carbon steel in Japan. The analysis was carried out using dynamic modeling. To classify the different kinds of alloys, stainless steel is subdivided into 13Cr, 18Cr, Cr–Ni, and Cr–Ni–Mo. Heat-resistant steel, structural alloy steel, bearing steel, and spring steel are also considered as steel alloys that include chromium. Carbon steel is classified into BOF (basic oxygen furnace) carbon steel and EAF (electric arc furnace) carbon steel to reflect differences in the raw materials from which they are composed. It was found that in-use stocks of chromium in the forms of stainless steel and other alloy steel in 2005 were 3.4 and 0.7 Tg, respectively. Other chromium stock as an alloying element in carbon steel was estimated as being 0.7 Tg in 2005, and it is dissipated in the carbon steel cycle. From the results of the dynamic model, the rates of ferritic stainless steel and other alloy steel recovered as carbon steel were approximately 40 and 80%, respectively, in 2005. Chromium accumulation in EAF carbon steel was dynamically analyzed from 1990 to 2030. On the basis of the assumption that future steel demand will be the same as the current demand, it is predicted that the mean chromium content in EAF carbon steel will gradually increase and reach 0.24% in 2030.

ＣｒとＮｉの物質収支を考慮したステンレス鋼のマテリアルフロー分析

This paper analyzed stainless steel stock and flow in Japan by using a dynamic modeling. Classifying different kind of alloys, stainless steel was subdivided into 13Cr, 18Cr, Ni–Cr, and Ni–Cr–Mo. Productions of heat-resistant steel, low-alloyed steels for machine structural use, cryogenic special steel, bearing steel, and spring steel were also taken into account as alloying steel including Cr and/or Ni in mass balances of Cr and Ni. In production processes, all raw materials for stainless steel were clarified by upholding mass balances of Cr, Ni and Fe. In-use stock of ferritics and austenitics at year 2005 were 4 Tg and 12 Tg, which could be converted to 3 Tg of Cr and 1 Tg of Ni. From the results of the model, collection rates as stainless steel scrap were estimated less than 35% for ferritics and more than 75% for austenitics. The collection rate of ferritics was estimated to be relatively small because some of ferritic scrap could be recovered as carbon steel scrap due to its magnetism. The dynamic model slso estimated that main source of ferritic scrap generation will be automobiles in the next decade. In order to promote recycling of ferritic scrap, recovery from automobiles would be important.

日本における鉄鋼材の循環利用に伴うクロムの物質フロー

Previous studies have pointed out that some quantity of ferritic stainless steel scrap is mixed with carbon steel scrap, thus resulting in the accumulation of chromium in carbon steel products. Chromium substance flow accounts for 97% of its consumption in Japan. This paper describes the analysis chromium substance flow in stainless steel, other alloy steels, and carbon steel in Japan. The analysis was carried out using dynamic modeling. To classify the different kinds of alloys, stainless steel is subdivided into 13Cr, 18Cr, Cr–Ni, and Cr–Ni–Mo. Heat-resistant steel, structural alloy steel, bearing steel, and spring steel are also considered as steel alloys that include chromium. Carbon steel is classified into BOF (basic oxygen furnace) carbon steel and EAF (electric arc furnace) carbon steel to reflect differences in the raw materials from which they are composed. It was found that in-use stocks of chromium in the forms of stainless steel and other alloy steel in 2005 were 3.4 and 0.7 Tg, respectively. Other chromium stock as an alloying element in carbon steel was estimated as being 0.7 Tg in 2005, and it is dissipated in the carbon steel cycle. From the results of the dynamic model, the rates of ferritic stainless steel and other alloy steel recovered as carbon steel were approximately 40 and 80%, respectively, in 2005. Chromium accumulation in EAF carbon steel was dynamically analyzed from 1990 to 2030. On the basis of the assumption that future steel demand will be the same as the current demand, it is predicted that the mean chromium content in EAF carbon steel will gradually increase and reach 0.24% in 2030.

Ball milling of stainless steel scrap chips to produce nanocrystalline powder

Nanocrystalline stainless steel powder was produced by ball milling of austenitic stainless steel scrap chips. The structural and morphological changes of samples during ball milling and after subsequent heat treatment were investigated by X-ray diffractometery, scanning electron microscopy and microhardness measurements. During ball milling the austenite in as-received chips partially transformed to the martensite phase with nanoscale size grains of ∼15 nm. This structure exhibited high microhardness value of about 850 Hv which is much higher than that for original samples. The deformation-induced martensite partially transformed to austenite after annealing at 700 °C for 1 h reducing the hardness of powder particles.

Dynamic Material Flow Analysis for Stainless Steels in Japan–Reductions Potential of CO2 Emissions by Promoting Closed Loop Recycling of Stainless Steels

Stainless steels are corrosion resistant alloys that are widely used in consumer goods and industrial equipment. Stainless steels contain scarce and energy intensive elements such as Ni, Cr, Mo, which means that closed loop recycling is preferable for sustainable stainless steel production. However, some stainless steels are not separated from ordinary steel scraps in the recycling processes and cannot be recycled as “stainless steel”. The objective of this study is to analyze the dynamic substance flow of stainless steels in Japan and assess the potential for reducing CO2 emissions by promoting closed loop recycling of stainless steels in the future. First, the authors analyzed material balance of input elements, i.e. Fe, Ni and Cr, in the production of stainless steels in 2002 to determine which aspects associated with the material flow of stainless steel cannot be elucidated from available statistical data. The amount of post-consumer stainless steel that would enter into society in the future was estimated by employing a Population Balance Model (PBM). It was found that only 2% of post-consumer stainless steel containing Fe–Cr alloys was collected as stainless steel scraps while the remainder was collected as ordinary steel scrap. Conversely, approximately 95% of post-consumer stainless steel consisting of Fe–Ni–Cr alloys was collected as stainless steel scrap. A CO2 emission reduction potential for a 1% increase in the closed loop recycling of stainless steel scraps of Fe–Cr alloys was estimated at 75 000 t/year by Life Cycle Assessment (LCA).

Characterization and leachability of electric arc furnace dust made from remelting of stainless steel

Electric arc furnace dust (EAFD) is a toxic waste product made in the remelting of scrap steel. The results of a Toxicity Characteristic Leaching Procedure (TCLP) conducted on a sample of EAFD originating from the remelting of stainless steel scrap showed that the total Cr and Cr (VI) liquor concentrations (9.7 and 6.1 mg/L, respectively) exceeded the Toxicity Characteristic Regulatory Level (TCRL). The EAFD showed a complex heterogeneous mineralogy with spinel minerals group predominance. A sequential extractions method has permitted the determination of the amount of available metals (potentially mobile component) from the EAFD as follows: Cr (3%), Ni (6%), Pb (49%) and Zn (40%). Solubility controls on Cr, Pb, Zn and Ni were identified in the EAFD. This means that the Cr, Pb, Zn and Ni concentrations in solution were controlled by the solubility of some phases from EAFD. The concentrations of Ni and Zn, which are metals not regulated by TCRL were below 0.41 and 1.3 mg/L, respectively. The solubility control on Pb was sufficient to decrease its concentration (<0.24 mg/L) to a level below the TCRL. However, the control on Cr was not sufficient to decrease its concentration (between 117 and 331 mg/L) to below the TCRL.

Effects of Both Flux Compositions and Oxidizing Conditions on the Dephosphorization of High-chromium Hot Metal by Using CaO-CaF2 Based Fluxes.

Owing to the spread of using coke for melting of stainless steel scrap and smelting reduction of chromium ore in the stainless steel production, it is thought that the development of an inexpensive and effective method of dephosphorization of chromium-containing hot metal is a necessity. In this study, the dephosphorization was investigated by a method of injecting the powder mixtures of lime and fluorspar with the carrier gas containing oxygen into chromium-containing hot metal. The results show clearly that even with about 30 mass% of chromium content, effective dephosphorization is possible. A powder mixing ratio of lime to fluorspar of 1/1 by weight has been found to be favorable, and under optimum oxidation conditions, chromium oxidation loss has been kept at 0.1 mass% or below at the chromium content of about 30 mass%. Finally, from a thermodynamic viewpoint, the oxygen potential of the dephosphorization with high chromium content levels has been considered to be determined by the formation reaction of CaO·Cr2O3.