Study of the role of reagents in magnesite flotation

Laden leach solution, generated from bioleaching of pyrometallurgical copper slags with a mixed culture of moderately thermophilic bacteria in a bioreactor, contains several base metals (Cu, Co, Zn) and a very high concentration of iron (33,9 g/ L). Further processing of cobalt and zinc to the respective final products requires preparatory iron removal from the laden leach solution. The direct iron removal from that solution as goethite was unacceptable because of the significant co-precipitation of copper and cobalt from the solution. The main aim of this paper is to study magnetite (Fe3O4) synthesis as an approach for iron removal to a value-added product as a step of the processing of a laden solution generated due to the bioleaching of non-ferrous metals in a bioreactor. Ferrous iron oxidation to ferric state was efficient when the addition of H2O2 (30 %) was combined with maintaining the pH 3,1-3,3 with NaOH and air purging. Solvent extraction with 25 % D2EHPA and 7,5 % TBP dissolved in kerosene efficiently separated the dissolved iron and the base metals from the processed solution. However, in the presence of H2, the iron was stripped from the organic solvent with low acid consumption. The applied precise control of the chemical precipitation and oxidation processes at 50 degrees Celsius allowed the iron content (11,7 g/ L) in the stripping solution to be removed efficiently as magnetite (Fe3O4). Based on the chemical content of iron, copper and sulphur, the synthesised nanoparticles of magnetite could be applicable in many sectors (steel, chemical, and electronics).

Section: Physicochemical Separation Methodsmentioning

confidence: 99%

Iron Removal From Laden Bioleaching Solution by Processes of Solvent Extraction and Magnetite Synthesis

Georgiev¹,

Nicolova²,

Spasova³

et al. 2023

Section: Physicochemical Separation Methodsmentioning

confidence: 99%

Features of Vibration Crushing of Geological Samples of Material

Fedoskina,

Yerisov,

Fedoskin

2023

An innovative method of vibro-impact grinding of geological samples, implemented in a vibrating jaw crusher with an inclined crushing chamber, is considered to obtain a product of -1 mm in one crushing cycle. The technique consisted in comparing the results of crushing quartzite and magnetite with a particle size of 60...80 mm according to the existing multi-stage technology using jaw and roller crushers, as well as the proposed single-stage technology using a vibrating jaw crusher. Three technological schemes for the preparation of samples of quartzite and magnetite were modelled with obtaining granulometric characteristics after each piece of equipment. The analysis of the results showed almost the same particle size distribution of the samples according to the multi-stage scheme: jaw crusher, screening -2mm, roller crusher, screening -1mm and single-stage: vibrating jaw crusher, screening -1mm. The output of the finished material was 80%. The studies substantiated the feasibility of creating a small-sized vibrating jaw crusher with a crushing ratio of i ≥ 100 for the preparation of geological samples, operating in an open cycle and replacing at least two pieces of crushing equipment, two screens and mounting elements, which significantly reduces the metal consumption of the structure, the occupied area and simplifies maintenance.

Section: Physicochemical Separation Methodsmentioning

confidence: 99%

Phytoremediation and Extraction of Colloidal Contaminants From Mine Effluents Through Legume Plants

Arahangelova,

Loukanov

2023

The bioaccumulation and environmental toxicity of colloidal contaminants have always been the focus of extensive research. Here we report efficient extraction of iron oxide colloidal contaminants from mine drainage effluents by phytoremediation with legume plants. The smallest fine particles with size less than 10 nm exhibit two wide absorption peaks at 350 and 495 nm, respectively. They have good dispersibility in aqueous environment and are highly resistant to removing or purification by any gravitational settings. The ultra-small nanosized particles (with average diameter 2-3 nm) can be bioaccumulated into the roots of soybean sprouts and might cause physiological stress and inhibition of the germination process. All experimental data found delayed growth, as well as decreased biomass production, which was observed in both the stem and root system of treated sprouts. Nevertheless, the immersed in mine effluent plants showed some resistance to the colloid toxicity. The light microscopic analysis also revealed the occurrence of more intensive symbiosis between the root tubers and the rhizosphere microbial communities in the case of phytorenmediation. The absorbance spectroscopic measurement demonstrated about 90 % efficient colloidal removement from the suspension within 10 days treatment. The atomic absorption spectroscopy analysis of mineralised sprouts cultured in synthetic mine effluents found that the highest concentration of accumulated iron in the legume plants was 258,02 ± 23,48 mg/100 g, which was achieved in suspension of 25 mM FeSO4. The presented report enables potential practical application of legume plants in the circumneutral passive treatment systems for remediation of mine effluents.