Toward environmentally friendly direct reduced iron production: A novel route of comprehensive utilization of blast furnace dust and electric arc furnace dust

Recycling and reutilization of smelting dust as a secondary resource: A review

Smelting dust is a toxic waste produced in metal-mineral pyrometallurgical processes. To eliminate or reduce the adverse environmental impacts of smelting dust, valuable components need to be selectively separated from the toxic components present in the waste. This paper reviews the chemical composition, phase composition and particle size distribution characteristics of smelting dust, and the results show that smelting dust has excellent physicochemical characteristics for recovering valuable metals. The process flow, critical factors, development status, advantages and disadvantages of traditional technologies such as pyrometallurgy, hydrometallurgy and biometallurgy were discussed in depth. Conventional treatment methods typically prioritize separating and reclaiming specific elements with high concentrations. However, these methods face challenges such as excessive chemical usage and limited selectivity, which can hinder the sustainable utilization of smelting dust. With the increasing scarcity of resources and strict environmental requirements, a single treatment process can hardly fulfil the demand, and a physical field-enhanced technology for releasing and separating valuable metals is proposed. Through analysing the effect of electric field, microwave and ultrasound on recovering valuable metals from smelting dust, the enhancement mechanism of physical field on the extraction process was clarified. This paper aimed to provide reference for the resource utilization of smelting dust.

Detoxication and recycling of chromium slag and C-bearing dust via composite agglomeration process (CAP)-blast furnace method

The utilization of virulent chromium slag has always been a worldwide problem, and lots of C-bearing dust produced in steel industry has not been utilized efficiently. Sintering is a potential method to treat these two kinds of solid wastes, but it is limited by small treatment capacity, incomplete detoxification of Cr(Ⅵ) when they were directly added into sintering process. In this study, an innovative technology of co-processing chromium slag and C-bearing dust via composite agglomeration process (CAP)-blast furnace method was put forward and systematically investigated. In the CAP, the chromium slag and C-bearing dust were first made into composite pellets and added into the matrix feed for co-sintering. The results showed that, 20% chromium slag and 5% C-bearing dust could be co-disposed by the CAP without destroying the quality of the sinters. Cr(VI) was completely reduced to Cr(III) or metal Cr. 12.83% Cr existed as metal Cr, and the rest of Cr existed in spinel as (Mg, Fe)(Cr, Al)2O4 or in silico-ferrite of calcium and alumina as Cr(Ⅲ). After blast furnace smelting, 90.22% Cr in sinters entered stainless mother liquor to be recycled.

Synthesis of Micro-Electrolysis Composite Materials from Blast Furnace Dust and Application into Organic Pollutant Degradation

A micro-electrolysis material (MEM) was successfully prepared from carbothermal reduction of blast furnace dust (BFD) and coke as raw materials in a nitrogen atmosphere. The MEM prepared from BFD had strong ability in removing methyl orange, methylene blue, and rose bengal (the removal rates of methyl orange and methylene blue were close to 100%). X-ray diffraction showed that the iron mineral in BFD was ferric oxide, which was converted to zero-valent iron after being reduced by calcination. Scanning electron microscopy showed that nano-scale zero-valent iron particles were formed in the MEM. In short, the MEM prepared from BFD can effectively degrade organic pollutants.

A Novel Technique for the Preparation of Iron Carbide and Carbon Concentrate from Blast Furnace Dust

Blast furnace (BF) dust is a typical refractory iron resource. A novel technology-based utilization of BF dust as iron carbide and carbon concentrate by applying carburization roasting followed by magnetic separation and acid leaching is proposed. Under optimized conditions, an electric arc furnace (EAF) burden assaying 80.79% Fe and 7.63% C with a corresponding iron recovery rate of 87.26% and a carbon concentrate assaying 67.06% C with a corresponding carbon recovery rate of 81.23% were prepared. Furthermore, the carburization behavior and separation mechanism were revealed using X-ray powder diffraction, scanning electron microscopy, and optical microscopy. The results show that the separation efficiency of iron carbide, gangue, and carbon is very low. Na₂SO₄ is a highly effective additive to strengthen the separation efficiency as it can enhance the carburization index, enlarge the iron carbide particle size, improve the embed embedded relationship of iron carbide and gangue, and promote the gangue leaching efficiency. The study demonstrates that preparation of iron carbide and carbon concentrate from BF dust using the proposed technology is a feasible method.