Genetic Variability Screening of the Leptolyngbya Boryana with Expressed ChrR Gene for the Biotransformation of Cr (VI) to Cr (III) Reduction

Chromium is well known pollutant for its mutagenicity, and carcinogenicity in humans. Excessive uses of chromium in leather tanning industries, stainless-steel production, and wood preservatives have resulted as chromium contamination in soil and water. This investigation indicates the effective use of Leptolyngbya boryana as an eco-friendly option to overcome Chromium (VI) toxicity in tannery effluents. The main objective of this research was to find out ChrR gene and its variability in the context of Cr (VI) stress. This is a novel study in the relation of Leptolyngbya boryana. Industrial polluted soil samples were collected and processed according to the standard protocols for ChrR variation and 16S rRNA gene. DNA was isolated and amplified through PCR. Amplified DNA was sequenced and aligned with the known sequences. In this study a strong co-relation was established in the nucleotide sequences of ChrR and 16S rRNA genes. MIC was determined for Cr (VI) and pure strains of Leptolyngbya boryana were identified and isolated from soil. In the present study presence of ChrR gene variability was recorded in Leptolyngbya boryana which is a cyanobacterium in the soil of tannery effluent under Cr (VI) stressed condition and its gene variability was confirmed by sequencing. We can conclude that Leptolyngbya boryana strain could be eco-friendly option to overcome Chromium (VI) toxicity in tannery effluents.

A Review of Circular Economy Prospects for Stainless Steelmaking Slags

The world of stainless steel production was 52 Mt in 2019, and the annual amount of slags including electric furnace, AOD converter, ladle, and casting tundish, was estimated at 15–17 Mt. Nowadays, only a minor fraction of slags from stainless steel production is utilized and a major part goes to landfilling. These slags contain high-value elements (Cr, Ni, Mo, Ti, V…) as oxides or in metallic form, some of them being environmentally problematic if dumped. Thus, any approach toward circular economy solutions for stainless steel slags would have great economic and environmental impacts. This contribution examines the slags from different process stages, and the available and new potential means to increase internal recycling and to modify slags composition and structure by optimizing their properties for reclaiming in high-value applications. Eventual methods are, e.g., fast controlled cooling and modifying additives. Means to recover valuable metals are discussed as well as potential product applications to utilize various slags with different chemical, physical, and mechanical properties. By integrating the treatments and steering of slags′ properties to the total process optimization system, the principles of circular economy could be achieved. Graphical Abstract

Different demand dynamics will bifurcate nickel supply

Significance Stainless steel production in China and Indonesia rose in the final months of 2020, tightening the market. Softer recent prices for stainless steel and NPI suggest near-term downside risk. Impacts Over two-thirds of nickel in stainless steel is recycled, but the industry is yet to establish protocols to assess battery recyclability. Curtailing exploration prospects, budget cuts at Russia’s Norilsk Nickel and Australia's Clean TeQ will offset others' modest increases. Norilsk Nickel faces continued Kremlin pressure to answer for the environmental damage caused by last year's large oil spill. Indonesia’s NPI output will gain one-third in 2021, but the extra output will stay onshore, feeding the nation’s stainless steel output.

Benefits from improved bath agitation with the RADEX DPP gas purging system during EAF highalloyed and stainless steel production

Modern production processes of high alloyed and stainless steel grades are subject to the cost-optimized production of raw steel or molten combined with high flexibility. Excellent mixing of the steel melt helps to improve mass and heat transfer in the EAF, in order to accelerate the melting of heavy scrap and alloys, decarburization, homogeneous superheating, alloy distribution, and to avoid skull formation and solid remainders that may obstruct tapping. The RADEX DPP system generates customer benefits by improving EAF processes during high-alloyed stainless steel making. The most important effect of the enhanced steel bath mixing besides improved heat transfer and decarburization is a decreased chromium oxidation. Firstly, chromium oxidation is decreased by improving the homogeneous distribution of carbon and chromium in the melt. Secondary, build-up of chromium-containing solids in the EAF hearth and skull formation is decreased by stronger melt movement. The cost savings of both effects economically justify the application of gas purging in EAF stainless steelmaking. Case studies are presented demonstrating the advantages. Ill.7. Ref. 7. Tab. 3.

The Use of High-Alloyed EAF Slag for the Neutralization of On-Site Produced Acidic Wastewater: The First Step Towards a Zero-Waste Stainless-Steel Production Process

Recycling of steelmaking slags has well-established applications, such as their use in cement, asphalt, or fertilizer industries. Although in some cases, such as the electric arc furnace (EAF) high-alloyed stainless-steel production, the slag’s high metal content prevents its use in such applications. This forces companies to accumulate it as waste. Using concepts such dematerialization, waste management, industrial symbiosis, and circular economy, the article drafts a conceptual framework on the best route to solving the landfilling issue, aiming at a zero-waste process re-design. An experimental part follows, with an investigation of the use of landfill slag as a substitute of limestone for the neutralization of acidic wastewater, produced by the rinsing of steel after the pickling process. Neutralization of acidic wastewater with both lime and slag samples was performed with two different methods. Two out of four slag samples tested proved their possible use, reaching desired pH values compared to lime neutralizations. Moreover, the clean waters resulting from the neutralizations with the use of both lime and slag were tested. In terms of hazardous element concentrations, neutralization with slag yielded similar results to lime. The results of these trials show that slag is a potential substitute of lime for the neutralization of acidic wastewater.