Flotation Wastes Research Articles

Manmade waste flotation with combined pulp treatment

Manmade waste flotation with combined pulp treatment

Accumulation and distribution of heavy metals in soil and food crops in the Pb–Zn mine environ. Case study: Region of Probištip, North Macedonia

The aim of the study was to investigate the exploration and distribution of various chemical elements in soils and vegetables from gardens in the region of Probištip, North Macedonia. This region was exposed to heavy metals pollution from Pb–Zn mining and flotation tailings landfill near the town of Probištip for 70 years. A total of 38 samples of various crops and vegetable products from 19 gardens were analyzed. The analyzes were carried out by ICP-AES (Al, Ba, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, Sr, V, and Zn) and by ICP-MS (As, Cd, Co, Cr, and Pb). It was found that the content of some potentially toxic elements (As, Cd, Cu, Pb, and Zn) in the soil samples from the gardens, exceeded the target values. From these results, it is clear that the contamination of the soils in this area is due to mining activities and the distribution of flotation wastes from the nearby flotation dump. It was also found that the contaminated soils lead to elevated levels of these elements in some vegetables from the gardens, especially those near the Zletovska River and the flotation waste landfill, exceeding the nationally permissible food content.

Individual and synergistic effects of modifications of the carrier medium of carbon-containing slurries on the viscosity and sedimentation stability

The study is devoted to revealing the individual and synergistic effects of modifications of the carrier medium of the coal-water slurries (CWS) based on coking coal and carbon-containing flotation wastes of this coal on the effective viscosity and sedimentation stability. Synthetic and natural wetting agents as well as liquid solvents (alcohol, oil, conventional liquid fuel, methyl ethers) and solid organic compounds exemplified by sawdust are used for this. The relationships between the effective viscosity, water separation ratio, and zeta potential for the CWS with the separate addition of a wetting agent and a solvent is established. The categories of fuel compositions are identified according to the “stability” criterion. The synergistic effect of the additions of a wetting agent and a solvent on the sedimentation stability and effective viscosity is demonstrated. The physicochemical model of interaction between the solid particles and the additives in CWSs is proposed.

Bioleaching Process for Copper Extraction from Waste in Alkaline and Acid Medium

Flotation wastes are becoming a valuable secondary raw material and source of many metals and semimetals worldwide with the possibilities of industrial recycling. The flotation tailings contain oxide and sulfide minerals that have not been sufficiently stabilized and form acidic mine waters, which in turn contaminate groundwater, rivers, and reservoi6sediments. An effective way to recycle these mine wastes is to recover the metals through leaching. While the focus is on acid bioleaching by iron- and sulfur-oxidizing bacteria, alkaline leaching, and the removal of iron-containing surface coatings on sulfide minerals contribute significantly to the overall environmental efficiency of leaching. For this study, static and percolate bioleaching of copper from flotation waste at the Bor copper mine in Serbia was investigated in alkaline and then acidic environments. The aim of the study was to verify the effect of alkaline pH and nutrient stimulation on the bioleaching process and element extraction. A sample was taken from a mine waste site, which was characterized by XRF analyses. The concentration of leached copper was increased when copper oxide minerals dissolved during alkaline bioleaching. The highest copper yield during alkaline bioleaching was achieved after 9 days and reached 67%. The addition of nutrients in acidic medium enhanced the degradation of sulfide minerals and increased Cu recovery to 74%, while Fe and Ag recoveries were not significantly affected. Combined bioleaching with alkaline media and iron- and sulfur-oxidizing bacteria in acidic media should be a good reference for ecological Cu recovery from copper oxide and sulfide wastes.

Unravelling the effect of impurities on the methanol-to-olefins process in waste-derived zeolites ZSM-5

One of the main challenges in the next decades for the chemical industry is the valorization of low-grade industrial waste streams into valuable materials, as their increasing amount can have a major environmental impact. For example, in copper mining industry, waste flotation tailings can be valorized into solid acid catalysts, such as zeolites. Numerous studies have shown that modification of zeolites by metal ions has a positive effect in their catalytic performance. However, the presence of impurities in waste-derived materials is usually disregarded. In this work, the influence of impurities in waste-derived zeolites ZSM-5 on the physicochemical properties and the catalytic performance in methanol-to-hydrocarbons (MTH) reaction was investigated. Flotation tailings from copper industry, mainly consist of SiO2 as quartz, next to Ca, Mg and Fe species. By altering the pH in the SiO2 precipitation step, the impurities content in the waste-derived zeolites ZSM-5 could be controlled. Chemical analysis confirmed the presence of Fe, Ca and Mg in low concentrations in the waste-derived samples. UV–Vis Diffuse reflectance spectroscopy (DRS) and electron paramagnetic resonance (EPR) showed the presence of different Fe species in the waste-derived samples in the form of isolated Fe3+, oligomeric FexOy species and some extended Fe2O3-like clusters. Temperature programmed desorption (TPD) of NH3 and infrared (IR) spectroscopy measurements after CO and pyridine adsorption were used in order to probe the effect of the cations present in the acidity of the waste-derived materials. It was found that the zeolite material with a higher amount of metal impurities contained less Brønsted acid sites and more Lewis acid sites. Catalytic testing showed that the metal impurities had a positive influence on the overall catalyst stability and the yields towards ethylene and propylene were respectively 8% and 6% up. Meanwhile, operando UV–Vis DRS showed the influence of impurities on the catalytic mechanism, as its increase led to the formation of less hydrocarbon pool species. This study not only show that waste can be transformed into value-added materials, namely a zeolite-based catalyst material, but also that the impurities present in the waste can further improve the catalytic performance of the solid catalyst.

Leaching of gold from flotation waste by thiourea

Throughout human history, gold has been the most sought-after and well-known precious metal in the world. It is synonymous with wealth in the financial market and jewellery. However, its use has a wide range of applicability in biomedicine, electronic engineering and other industries. Primary gold resources are limited and have been significantly depleted in recent decades. To cover the current demand, it is necessary to process secondary sources containing gold such as heaps, tailings, lean ores or electrical waste. New and especially more efficient technological procedures are needed for the processing of these secondary sources. From an environmental point of view, a hydrometallurgical process is considered to be more appropriate than a pyrometallurgical process, in which very toxic fumes enter the air. This work investigates the leaching of gold from flotation wastes using thiourea. It is flotation waste that is the target group of materials that are a source of precious metals. An interesting gold content is present in our waste sample (Hodruša Hámre tailings pond), but its evaluation depends on the setting of suitable technological conditions. In this work, thiourea is used as an alternative leaching agent to toxic cyanide, which is banned in Slovakia and many countries around the world due to its high environmental risk. The results of the study are described with respect to the gold recovery under optimized thiourea leaching conditions.

The use of waste, fine-grained carbonaceous material in the process of copper slag reduction

The article presents the results of the research on the reduction of the high-copper slags produced in the single-step Outokumpu blister copper production process, carried out by KGHM Polska Miedz. The company is the fifth largest blister copper producer in the world. The tested slags containing 12–16 wt%. Cu, < 4 wt% Pb and up to several wt.%. Fe are processed in an electric furnace using coke breeze as a reducing agent. As an alternative reducer, a fine-grained carbon-bearing waste material (the so-called flotoconcentrate), produced in the process of enrichment of coal sludge, has been proposed. The aim of the presented investigation of the slag processing was the recovery of the valuable metals (Cu and Pb) and the secondary materials that could be directly used in the various branches of the economy (so called secondary slag). The results of the conducted experiments show that the quick coke, traditionally applied in this process, can be replaced with pellets made from the waste flotation concentrate. The yield of copper removal from all the slag batches examined was 96–98%. The compositions of the Cu–Pb–Fe alloys and slags obtained in the experiments were acceptable, since the degree of copper and lead removal from the primary slag remained within the limits typically observed for the industrial-scale processing. Since the final copper content (wt.) in the waste was lower than 0.4 wt%, and the final lead content (wt.) was less than 0.5%, the slag constitutes a waste material that may be used for road making and in the building industry. The proposed approach may bring the cost down up to 50% in comparison to the commonly used carbon-based reducing agents.

Bioleaching for detoxification of waste flotation tailings: Relationship between EPS substances and bioleaching behavior

The production of large volumes of waste flotation tailings results in environmental pollution and presents a major ecological and environmental risk. This study investigates bioleaching of waste flotation tailings using Acidithiobacillus ferrooxidans. The experiments were performed with 5.00% solid concentration, pH 2.0 with 100 mL medium for 25 d in the lab. The pH, OPR, metal concentration, dissolved organic matter (DOM) in leachate and extracellular polymeric substances (EPS) were recorded. Bioleaching tailing materials were finally characterized. Results showed that microorganisms, acclimating with mine tailings, effectively accelerated the bioleaching process, achieving maximum Zn and Fe extraction efficiencies of 95.45% and 83.98%, respectively, after 25 days. Compared with raw mine tailings, bioleaching could reduce 96.36% and 95.84% leachable Zn and Pb, and Pb presented a low risk (4.13%), while Zn, Cu, and Cr posed no risk (0.34%, 0.64%, and 0%). Toxicity and environmental risk analysis revealed bioleaching process significantly reduced the environmental risk associated with mine tailings. EPS analysis indicated that the loosely-bound EPS (LB-EPS) and tightly-bound EPS (TB-EPS) fractions contained different organic substances, which played different roles in the bioleaching process. Pearson correlation analysis revealed that EPS was highly correlated with bioleaching behavior (p < 0.05), and EPS was the main factor affecting the bioleaching process, promoting bioleaching in the LB-EPS and TB-EPS fractions.

APPLICATION OF ANTHRACITE FLOTATION ENRICHMENT WASTE IN PRODUCTION OF POROUS AGGREGATE BASED ON LIQUID-GLASS COMPOSITIONS

Reduction of reserves of traditional natural raw materials for production of porous aggregates forces to look for new ways of its replacement by various types of technogenic raw materials. At the same time, the experience of advanced Western foreign countries has shown the practical, economic, environmental and technical feasibility of this direction and application as a tool for protecting the natural environment from pollution. In the present work it is shown that the most appropriate use wastes fuel and energy complex in the manufacture of insulating materials, such as porous aggregates with heat conductivity not more than 0.25 W/m•operating system. Waste from anthracite flotation enrichment was used as a thinning agent and burnout additive. Waste flotation enrichment of anthracites have an increased content of PP (loss during calcination = 42.4 %) and carbon content (C = 13.84 %), so they were used for the production of porous aggregate not only as a thinner, but also as burnout additives. Developed on the basis of waste flotation enrichment of anthracites and beet compositions for porous aggregates, which have high rates of compressive strength and softening factor, and the mark on the bulk density does not exceed M400. Studies have shown that the porosity on the exterior of the product, in contrast to the internal almost no form, ie waste flotation enrichment of anthracites contributes to the porous filler closed pores. The presence of pores of isometric shape and oval closed porosity in the porous filler gives it mechanical strength, and slit-like pores have a harmful effect. Innovative proposals for obtaining a porous aggregate have been developed. A patent of the Russian Federation was obtained for the obtained method of producing a porous filler based on a liquid-glass composition.

Integrating Flotation and Pyrometallurgy for Recovering Graphite and Valuable Metals from Battery Scrap

Since the current volumes of collected end-of-life lithium ion batteries (LIBs) are low, one option to increase the feasibility of their recycling is to feed them to existing metals production processes. This work presents a novel approach to integrate froth flotation as a mechanical treatment to optimize the recovery of valuable metals from LIB scrap and minimize their loss in the nickel slag cleaning process. Additionally, the conventional reducing agent in slag cleaning, namely coke, is replaced with graphite contained in the LIB waste flotation products. Using proper conditioning procedures, froth flotation was able to recover up to 81.3% Co in active materials from a Cu-Al rich feed stream. A selected froth product was used as feed for nickel slag cleaning process, and the recovery of metals from a slag (80%)–froth fraction (20%) mixture was investigated in an inert atmosphere at 1350 °C and 1400 °C at varying reduction times. The experimental conditions in combination with the graphite allowed for a very rapid reduction. After 5 min reduction time, the valuable metals Co, Ni, and Cu were found to be distributed to the iron rich metal alloy, while the remaining fraction of Mn and Al present in the froth fraction was deported in the slag.

Improving the Flotation of Fine Coal Slurries

The properties of fine coal slurries at OOO MMK-Ugol and their flotation are studied. To improve the flotation of finely disperse coal slurries, more effective reagent combinations are employed; TPA collection agent and Sinterol flocculant are considered. In the laboratory, optimal flotation conditions are developed for fine coal slurries. In these conditions, coal enrichment is more efficient thanks to decrease in the loss of organic mass with the flotation wastes. In addition, the reagent consumption is decreased by a factor of 2–3. The effectiveness of Sinterol flocculant is confirmed by industrial tests at OOO MMK-Ugol. Supplying Sinterol at a rate of 1 × 10–3—3 ×10–3 kg/t of coal in the course of flotation increases the yield of concentrate, while also decreasing its ash content by 1.5–2.0%. That decreases the loss of organic mass with the flotation wastes. Increase in the ash content of the flotation wastes by 8.3–13.8% also decreases the loss of organic mass with the wastes.

The research of the effect of oxidizing agents on the burning process of the carbon-containing component of ceramic masses and their firing properties

The efficiency of using different oxidizing agents to intensify the burnout of the organic component of ceramic masses is investigated. The ceramic masses contained coal flotation wastes with a high carbon content as a fuel-mineral additive. Various inorganic salts, which are oxygen donors during the firing of ceramic masses and form oxidizing agents O2, NO2, N2O during their thermal decomposition, are considered. A new calculation method for determining the content of an oxidizing salt in a ceramic mixture is proposed. This method takes as a basis the amount of «effective oxygen» that released during the thermal decomposition of the oxidizing agent, but not its mass, as it was before. The method allows calculating the rational content of an oxidizing agent necessary for efficient combustion of the carbon component of fuel-mineral additives. When calculating, it is necessary to take into the composition of the organic part of the additive, its content in the ceramic mass and the degree of carbon oxidation. Calculation of the rational content of the oxidizing agent according to this method allows avoiding its excessive and economically unreasonable use. The effect of oxidizing agents and their combinations on the burnout of the carbon component and the firing properties of the masses for wall ceramics is studied. The masses contained 15 % of coal flotation waste with a carbon content of 29 %. It was found that the use of oxidizing agents accelerates the burnout of the organic part of the masses, improves the appearance and mechanical properties of ceramic samples. The use of combined oxidizing agents with different decomposition temperatures makes it possible to create an oxidizing medium in a wider temperature range. This positively effects on the mechanical properties of ceramics. The optimal combinations of oxidizing agents NH4NO3+Ca(NO3)2 і NH4NO3+NaNO3, which made it possible to obtain ceramic samples with a compressive strength 10 МПа, were determined. This mechanical strength meets the requirements of the State Standard of Ukraine B M.2.7-61: 2008 in part of ordinary brick of the M100 brand.

The effect of phosphate flotation wastes and phosphogypsum on cattle manure compost quality and plant growth

In this study, the effect of phosphates flotation wastes (PFW) and phosphogypsum (PPG) on organic biomass degradation, compost quality, and plant growth was examined. Our results showed that PFW and PPG improve composting mechanisms, accelerate organic substance degradation, and increase fertilizing elements (P2O5, K2O, MgO, CaO). The low level of C/N ratio in the finished composts reflects the good quality of the prepared composts. The effect of PFW and PPG additives on plant growth was evaluated using chickpea plants. Addition of PFW and PPG enhanced significantly chickpea plant growth and development, compared to the control, especially when added simultaneously. These results indicate that PFW and PPG can be utilized in compost formulations, and as fertilizers in agricultural practices to improve chickpea plant growth and development, while at the same time reducing the environmental and health risks associated with their disposal.

Combustion of Coal Flotation Wastes and Woodworking Wastes in Blends and Suspensions

The utilization of flammable wastes in composite fuels for boiler combustion is discussed. The combustible materials considered are coal flotation wastes, long-flame coal, sawdust, and cardboard. These components undergo combustion in the form of a bed of dry mixture or as aqueous suspensions. The following characteristics are determined: the minimum ignition temperature, the delay time of gaseous or heterogeneous ignition, the maximum temperature in the combustion zone, and the calorific value of the fuels. Sawdust-based compositions may be recommended for kindling and to minimize the ignition time. The heat liberation in the combustion chamber may be significantly increased by using mixtures of sawdust, coal slurry or filter cake, and coal dust. The use of such wastes as industrial fuels is very promising.

Improved Coal Flotation with Sinterol Modifier

The flotation of coal with different ash content when using Sinterol modifier is studied. If the modifier consumption is 1.0–3.0 g/t of coal fines, the extraction of the coal’s combustible mass in the concentrate is increased; the selectivity of the process is increased; and the loss of the coal’s organic mass with the flotation wastes is decreased. The improved flotation may be explained as follows. The Sinterol modifier is adsorbed on active sections of the coal surface by means of hydrogen bonds with its polar groups, in a configuration such that the hydrocarbon groups face the water. That results in a more hydrophobic surface of the coal particles and improves their floatability. The modifier is more effective in flotation when supplied before the collection agent.

Environmental, economic and energetic benefits of using coal and oil processing waste instead of coal to produce the same amount of energy

The replacement of coals by less environmentally hazardous coal-water slurries with and without petrochemicals is often discussed with an emphasis on quite a long list of advantages of composite fuels. In this research, we perform a compound analysis of the main prospects of switching from coal to slurries containing coal and oil processing waste. The main focus is on comparing a group of parameters to produce the same amount of heat from the combustion of coals and high-potential fuels. The compound analysis includes fuel consumption, the most hazardous anthropogenic emissions (sulfur and nitrogen oxides), the mass of the ash residue, the cost of components as well as their properties and concentrations. The numerical values of the relative efficiency factor of fuels based on municipal and industrial wastes vary in a wide range from 2 to 165. The best results are shown by the slurries based on flotation wastes (filter cakes) of coking and nonbaking coals (ranks C and N). For them, the aggregated criterion indicators are 70–90% higher than for the respective coals. A forecast has been made on the amount of energy that can be generated using fuels from wastes. According to our forecast, the waste-based fuels under study may be used to generate 773 TWh of energy annually.

Improving the quality of coal is one of the factors in intensification of combustion processes in coal-based energy

For flotation enrichment of coals, spent engine oils modified with ozone were used. Preliminary ozonation contributes to the increase in the share of low-boiling components in the compositions of spent oils, also it reduces the viscosity of reagents and improves their flotation properties when coals are enriched. By flotation of coal, using ozonized spent oils, the yield of concentrate significantly increases, ash content is reduced, mineralization of waste flotation is increased, and as a result, the selectivity of the process is increased as well.

Mineralogical-and-technological assessment of mining and processing waste flotation in terms of low-grade copper-molybdenum ore

Mineralogical-and-technological assessment of mining and processing waste flotation in terms of low-grade copper-molybdenum ore

Utilization of coal-flotation wastes at OAO TsOF Belovskaya

Flotation wastes at OAO TsOF Belovskaya are studied with a view to their disposal in systems for the combustion of high-ash coal. Analysis indicates that, if the flotation wastes are mixed with regular coal, they may be used as fuel in low-temperature fluidized-bed furnaces. The introduction of such furnaces in the drying department at OAO TsOF Belovskaya is recommended, for use in the drying of coal concentrates.

Possibility of uranium and rare metal recovery in the Polish copper mining industry

Wastes originating from copper mining create a big problem regarding their quantity and toxicity. However, they are a source of valuable metals, and new hydrometallurgical technologies are becoming more economical in the recovery of these metals. In most cases, the leach liquor also contains uranium which can be easily recovered. This paper reports on the results of a universal method for the extraction of uranium (with the possibility of other valuable metals) from different raw materials (ground ores and/or flotation wastes). An innovative process of uranium dioxide synthesis by the sol–gel technique has been developed as well. The synergistic effect of the application of both techniques (extraction and sol–gel) led to the elaboration of a consistent technology for the recovery of uranium from copper mining materials and wastes. The direct method (with the possibility of elimination the precipitation step) of uranium dioxide synthesis can be used to generate a nuclear fuel precursor for present and future generation nuclear reactors, e.g. pressurized heavy water reactors or fast breeder reactors.