Heavy Media Separation Research Articles

Upgrading low-rank lignite coals (Çan, Çanakkale/Turkey) by leaching

ABSTRACT Reserve of quality coal mines has been getting decreased all over the world, as well as Turkey. Presently, there is a concentrated effort in academia conducting intensive studies aimed at enhancing the quality of low-rank coals for utilization. Turkish lignite, containing high sulfur and ash, can be treated to remove sulfur and ash from the coal using physical, chemical, and biological methods. In this study, chemical (humic acid) and biological (Pseudomonas putida) leaching methods were applied for removing of pyritic and organic sulfur from a high sulfur content lignite coal taken from Çan (Turkish Coal Enterprises (TKI), Çanakkale, Turkey) region. The experimental study consisted of the two main stages as (i) column chemical leaching and bioleaching, and (ii) a combination of chemical and biological process at atmospheric pressure on physically the treated/cleaned lignite coal by heavy media separation. A clean coal product with 4.40% ash and 2.09% S content was obtained by both using chemical and biological leaching to the lignite coal treated/washed (16.46% ash and 6.14% S).

Efficient separation and recovery of barium from barium slag via hydrometallurgical approach: Process design, thermodynamics research and mechanism investigation

The accumulation of barium slag (Bs) not only presents significant environmental challenges but also results in the inefficient utilization of resources. The present study investigates the scientific problems of hydrometallurgical methods for converting compounds containing barium in Bs into desired barium salts, with a specific focus on acid treatment, flocculation and precipitation of soluble barium from the leaching solution, as well as heavy media separation in the Bs residue. The experimental findings demonstrate that over 98.5% of the compounds containing barium undergo successful conversion into BaCO₃ and BaSO₄, achieving high purities of 98.7% and 79.4%, respectively. A crucial aspect of the mechanism lies in the interaction among ions, which facilitates the conversion of compounds containing barium into the desired barium salts. Additionally, the utilization of flocculants significantly enhances the efficiency and rate of flocculation for the BaCO₃ turbid fluid, wherein PAM and C-PAM exhibit superior effects in comparison to A-PAM. The reduction in the thickness of the electrical double layer, achieved through the application of flocculants, plays a pivotal role in expediting particle precipitation. Moreover, thermodynamic analysis illuminates the energy changes and the transformation processes during the recovery of barium from Bs. The study concludes by presenting a strategy for cleaner production to recover desired barium salts with Bs.

Spatially permeable screening distribution characteristics of banana-type vibrating screen material groups and industrial application

ABSTRACT Screening is a critical technology to achieve clean and effective use of coal. Due to their ability to achieve equal-thickness screening and excellent working efficiency characteristics, banana screens are widely utilized for material classification. The current work employs a vibration test and analysis system to investigate the laboratory-scale and industrial banana screens’ kinematic features. The screen surface’s amplitude gradients at the inlet and outlet ends of the laboratory and industrial scale banana screens were 0.5 mm and 7.5 mm, respectively, verifying the “strong-in, weak-out” transfer law of the vibration energy. The results of the 6 mm screening experiment in the laboratory indicated that the coal samples were concentrated in the middle of the screen surface with the highest screening efficiency of 95.05% and the lowest total mismatch content of 2.68%. A Birtley’s four-stage banana screen was utilized to classify the 6 mm raw coal during the on-site heavy media separation at the Tunbao coal processing plant. Besides, a better screening performance was obtained with an efficiency of 89.92% and total mismatch content of 5.31%. The differences in accuracy of the distribution rate curves were all less than 5%, indicating that the laboratory banana screen is a prominent guide for industrial applications.

Application of lean Six Sigma to improve the dense medium separation performance at a diamond processing plant in Namibia

Lean Six Sigma (LSS) is a rigorous, data-driven, and results-oriented process improvement philosophy. To date, there is no evidence of a study of the application of LSS in a diamond plant. One of the most common recovery methods in the diamond industry has been dense medium separation (DMS), also known as heavy medium separation (HMS). The main purpose of the study is to investigate how to implement LSS to improve the dense medium separation performance at a diamond plant. Further, we investigate the factors impacting DMS by finding the most relevant factor/s and applying the principles of Lean and Six Sigma to improve the performance of dense medium separation (DMS) at a diamond plant in Namibia. The research found out that factors affecting DMS include cyclone pressure, medium density, viscosity, and worn cyclone parts and maintaining these parameters within narrow limits in relation to the correct set points is beneficial. Also, the study established that, operational conditions (cyclone pressures and medium densities) are the topmost factors affecting DMS followed by viscosity and lastly, equipment dimensions. The application of LSS reduced downtime delays and boosted the associated production, thus achieving cost-efficiency, improved DMS performance and reducing waste. Diamond mines are found in large numbers in Africa, and this study will help the mines to improve their efficiency. Further, using the lens of theory of swift and even flow, the LSS is applied in the diamond company to streamline the DMS performance. Further, it poses key implications for future LSS research.

Intelligent control of heavy media separation

Intelligent control of heavy media separation

Intelligent control of heavy media separation

Intelligent control of heavy media separation

The study of enhanced gravity concentrator for maceral enrichment of low-rank coal with heavy medium

ABSTRACT The enhanced gravity concentrator with water medium has been used for the low-rank coal maceral enrichment and achieved a favorable effect. This study utilized the magnetite powder as the separation medium in the enhanced gravity separation test. The enhanced gravity separation with different medium was contrasted, the heavy medium separation possessed a more excellent separation mechanism and better effect, and the vitrinite content and recovery of concentrates was increased to 80.40 vol.% and 54.85%. In addition, the results of float–sink test and enhanced gravity separation with heavy medium were compared under the same separation density, the difference of vitrinite content and between the two methods was below 5%, and the vitrinite recovery of enhanced gravity separation was increased to 77.9% with the separation medium of 1.40 g/cm3. The density difference of macerals was proved by the EDS and XRD measurement, the more quantity of polycondensation aromatic rings and tighter microcrystalline structure leads to the higher density of inertinite.

Effect of flotation fractions of long-flame coal on regulation of sulfur and coke reactivity during pyrolysis of high-sulfur coking coal

The flotation fractions of a long-flame coal were obtained by heavy medium separation method, and its effect on regulation of sulfur and coke reactivity during pyrolysis of high-sulfur coking coal were investigated by FT-IR, Raman, TG, Gieseler fluidity, N2 adsorption, XRD. The results show that the low density fractions contain more aliphatic side chains and unstable aliphatic structure, while the high-density fractions show higher amount of minerals and inert components. Low density fractions have the highest sulfur removal rate due to lower content of alkaline minerals and more aliphatic side chains. The medium molecular weight component in the low density fractions has little effect on properties of metaplast. Higher minerals and inert components in high-density fractions deteriorate the metaplast more obviously. Meanwhile, order of the coke's microcrystalline structure is reduced and the defect sites increase, and consequently, reactivity of the coke increases.

ФИЗИКО-ХИМИЧЕСКИЕ И ЭЛЕКТРОХИМИЧЕСКИЕ МЕТОДЫ МОДИФИЦИРОВАНИЯ СВОЙСТВ АЛМАЗОВ И КОМПОНЕНТОВ РУДНОЙ ПУЛЬПЫ ПРИ СЕПАРАЦИИ АЛМАЗОСОДЕРЖАЩИХ КИМБЕРЛИТОВ

The main deposits of kimberlite ores located in the regions of Western Yakutia are enriched at the ALROSA diamond extraction factories using a similar technology, in which the maximum completeness of extraction and safety of diamond crystals is ensured by the stages of schemes. The bulk of diamond crystals is extracted in the processes of heavy medium, sticky and foam separation, the effectiveness of which is determined by the properties of diamonds, kimberlite minerals and the media separating them. The article presents the results of theoretical and experimental studies carried out by ICEMR RAS together with the largest universities in Russia, scientific and industrial enterprises of ALROSA. It is shown that the use of combined energy methods of destruction and removal of hydrophilizing formations on diamond crystals provides hydrophobization of their surface in the processes of sticky and foam separation. It has been established that the efficiency and economic indicators of the process of dense medium separation of diamond-containing raw materials are due to the stability of the technological properties of the weighting agent of the ferrosilicon medium and the suspension prepared on its basis. The method for modifying the corrosion resistance of ferrosilicon by nitriding its surface has been substantiated and tested. The proposed method makes it possible to create a protective shell on the surface of the granules, preventing their destruction upon contact with corrosive components of the water-air environment. Semi-industrial tests have established the possibility of increasing the extraction of diamonds into concentrates for sticky and foam separation by 4 and 5.2%, respectively. The results of laboratory tests have confirmed the possibility of reducing the corrosion rate of ferrosilicon by 5-6 times in the process of dense medium separation.

Characterizing magnesite heavy-media separation screenings as promising technogenic raw materials

Introduction. This article discusses the possibility of using technogenic raw materials for the production of magnesia and magnesium oxide. The analysis of domestic industry supply with magnesite and magnesian raw materials is presented. Man-made minerals, such as magnesite screenings, produced in the course of heavy-media separation of ore, are noted to be a promising source of this type of raw material. It has been established that this type of raw material is poorly studied. Research methodology. The applied research methods were substantiated to establish the amount and form of magnesium oxide in the magnesite screenings of the Satka deposit. Results and discussion. A significant amount of both current and accumulated screenings at the site in Satka and their chemical composition allow us to consider them as a promising technogenic raw material for magnesium oxide production. The work has determined the distribution of magnesium oxide by size classes. On the basis of elemental analysis, it was decided to recognize the object under study as a suitable mineral for processing. The thermogravimetric analysis of magnesite screenings made it possible to establish the forms of magnesium oxide in the material. Conclusions. Analysis of the results obtained allows us to assert the possibility of processing the studied technogenic raw materials, but the presence of magnesium oxide in the composition of solid solutions with calcium carbonate predetermines the use of chemical enrichment methods.

Role of mineral flotation technology in improving bitumen extraction from mined Athabasca oil sands III. Next generation of water‐based oil sands extraction

AbstractCurrent water‐based oil sands extraction operations are unsustainable, due to their consumption of large quantities of water and energy, generation of large volumes of fluid fine tailings, and rapid expansion of tailing ponds. From a brief analysis of the historical evolution of water‐based oil sands extraction, it has been identified that the use of conventional dispersed air flotation to recover liberated bitumen from oil sand slurries is mainly responsible for the high consumption of water required and the fluid fine tailings generated. Based on mineral flotation principles, a new concept is proposed, whereby water‐based oil sands extraction is simplified as a process of transferring hydrophobic bitumen from hydrophilic surfaces (sands) to hydrophobic surfaces (bitumen carriers). Compared to existing bitumen extraction technologies, bitumen liberation from sands is accelerated by attrition/scrubbing, and the liberated bitumen is recovered from the oil sand slurry by hydrophobic coagulation and heavy media separation. This concept is verified from preliminary laboratory tests for processing (above) average grade oil sands. The water required is significantly reduced from 100 to 150 wt% of the ores processed (as seen in current commercial operations) to 30‐40 wt% of the ores. Virtually no fluid fine tailings are generated, with the potential of eliminating tailing ponds. The tailings produced after bitumen extraction are paste‐like, containing >60 wt% solids, which can be directly disposed of in the mining pit, with little or no further treatment. Future research is needed to justify and refine the concept in large‐scale tests and engineer it into commercial operations.

Metallurgical Evaluation of the Hoidas Lake Rare Earth Deposit

Hoidas Lake lies in the Northern Rae Geological Province, in the general vicinity of many of Saskatchewan's large uranium mines. The mineralogy of the Hoidas Lake rare-earth deposit differs from most other such deposits in that it is hosted in equal abundance in veins containing apatite and allanite mineral groups. Hoidas Lake also differs from other deposits in that it contains a significant amount of heavy rare-earth elements, such as dysprosium. This abundance of heavy Rare Earth Elements (REE’s) is significant, as there is a growing demand for the heavier rare earths in high-tech manufacturing (such as the use of dysprosium in the manufacturing of hybrid car components). Recently, metallurgical testing was performed on a Hoidas Lake REE deposit composite. These investigations included characterization, flotation testing, heavy media separation, magnetic separation testing, whole ore leaching studies, bond work index grindability testing, and relative abrasion index testing. This paper summarizes this research effort.

UTILIZATION OF FLOTATION IN COPPER EXTRACTION FROM POLYMETALLIC ORE

The aim of this study was to examine flotation of utility metals from poor polymetallic ores and verify the potential for profitable yields in connection with potentially economic deposits of non-ferrous metals. The paper describes results in flotation concentrate research to recover copper from polymetallic ore. The polymetallic ore from Zlate Hory deposit (Czech Republic) was subjected to crushing, grinding, and screening to prepare feed for separation with mesh size under 200 microns. The heavy medium separation was performed in tetrabromethane with a density of 2.967 g.cm-3. The float and sink products were obtained and tested for chemical composition. Next, the treated polymetallic ore sample was subjected to flotation. In flotation, various dosages of collector (PAX) and various pH were tested, at which pyrite was depressed. The recovery of metallic copper in the concentrate increased with the collector dose. As the pH of the medium increased, the pyrite content in the concentrate dropped. The lowest content of pyrite, i.e. 4.01 %, was obtained at pH 10. In the original polymetallic ore, the Cu content was 0.41 % after subsequent treatment and flotation tests, the Cu content increased to 1.38 % with Cu recovery 86.18 %. Keywords: Copper; Flotation; Polymetallic ore; Potassium amylxanthate (PAX); Zlate Hory   DOI 10.35180/gse-2020-0030

Recovery of Apatite From Ore Slimes Using Centrifugal Heavy Liquid Separation

The aim of this study is to determine the feasibility of using a centrifugal heavy medium separation (CHMS) method to obtain apatite concentrates from ore slimes (particle size < 45 µm, 4.5% P2O5). The effects of the specific gravity, centrifugal speed, and time on the P2O5 content of the product and its recovery were investigated based on the Box–Behnken approach. X-ray fluorescence (XRF) spectroscopy, x-ray diffraction (XRD) analysis, and thermogravimetric (TG) analyses were performed to evaluate the properties of the product. The experimental findings indicate that each experimental parameter had a strong effect on the recovery of P2O5 from the ore slimes. The final product consisted mainly of hydroxyapatite along with aragonite, while its P2O5 content exceeded 30% P2O5, with recovery of 99.81%. The minor element ratio and CaO/P2O5 ratio were found to be 0.02 and 1.66, respectively. These values meet industrial requirements.

Upgrading low-rank coals (Çan, Çanakkale/Turkey) by float-sink separation in dense media

ABSTRACTTurkey coal reserves are mainly lignite (brown coal) and the majority of these reserves contain high-ash/sulfur coals, therefore, it is important to evaluate these low-quality lignite coals. Most of the produced lignite is utilized at the coal power stations in Turkey. The polluting gases containing sulfur dioxide after burning of low-quality coals are the main reason for air pollution, acid rain, and some respiratory systems diseases. In order to avoid these problems, high ash and sulfur-containing coal in our country need to be improved. In this study, the sink-float tests (heavy media separation) were applied to increase the quality of coal samples so that the ash and the impurities could be removed using a high ash-sulfur content coal sample (36.96% ash, 6.94% S and calorific value 3185 kcal.kg−1) taken from TKI (Turkish Coal Enterprises) Çan (Çanakkale, Turkey) lignite coalfield. The results of the float-sink tests showed that the most convenient washing operating density was 1.6 g/cm3, and the weight yield of the clean coal was 53.16%wt. (70.94% coal recovery) with 16.46% ash, 6.14% S with calorific value 5000 kcal.kg−1 using 10–0.5 mm size fraction of the coal.

Simulation-aided studies of heavy-media separation in Angouran lead and zinc ore

ABSTRACTPre-concentration of lead and zinc ore in Calcimin (public Co) which is done using heavy-medium cyclones (HMC) undergoes lots of inefficiencies and not in the desired manner. Considering the fact that feed material is variable in the case of Zn–Pb grades, it is important to make HMC plant flexible when facing different ore types. The present study aims to prepare a predicting tool which can determine the operational parameters of HMC plant such as density separation and predict the properties of the final product e.g. Zn–Pb grades and recoveries using existing models. After determining the feed ore characterizations including particle size distribution, XRF, XRD, and high-density sink-float tests, an existing empirical model for high-density HMC was used. Inserting the data obtained from ore characterization tests in existing models and solving necessary calculations makes it possible to predict the behavior of HMC plant at different ore types and select the most favorable operational conditions without doing a mass of experimental work. An optimal flowsheet of HMC plant was proposed as an example for the studied sample which shows the possibility of producing a pre-concentrate with Zn and Pb grades of 36.60 and 3.24%, respectively, with the recoveries of 93.66 and 90.31%.

Photovoltaic module recycling, a physical and a chemical recovery process

End-of-life photovoltaic modules can be hazardous wastes if they contain hazardous materials. The main problem arising from this type of waste is the presence of environmentally toxic substances and the poor biodegradability of the waste, which occupies great volumes when landfilled. For these reasons, photovoltaic modules have to be treated before landfilling as required by the legislation. The subject of this paper is the polycrystalline silicon type photovoltaic modules. They were treated with a physical and a chemical process. The physical process was aimed at the recovery of glass, metals, and the polyvinyl fluoride film. The modules were initially shredded with a knife mill and then processed with heavy medium separation, milling, and sieving. The glass (76%) and 100% of the metals were recovered respectively, at a grade of about 100% and 67%. Finally, a flow sheet of the physical process was proposed. The chemical process was aimed at identifying the best conditions which allow the dissolution of the EVA (ethylene vinyl acetate), that is the polymer that attaches the three layers that make up the module, namely the glass, the polycrystalline silicon, and the polyvinyl fluoride support. The experimental factors investigated were: type of solvent, thermal pretreatment, treatment time, temperature, and ultrasound. The best conditions to completely dissolve EVA in less than 60 min were the use of toluene as a solvent at 60 °C combined with the use of ultrasound at 200 W, while the pretreatment at 200 °C appeared to be useless.

Beneficiation of Sugarcane Bagasse Boiler Ash via Production of Syntactic Foams and Thermal Refractory Materials

Aqueous solutions of sodium polytungstate were used to fractionate samples of sugarcane bagasse ash by heavy media separation. Practically no cenospheres were recovered from the ash samples. The method was successful in separating fibrous carbonaceous particles with a uniform surface from particles containing more silica and having a less uniform surface. A geopolymer refractory brick having satisfactory durability was produced from sugarcane bagasse ash with metakaolin and ball clay fillers and a sodium metasilicate/hydroxide activator liquor. Drying and firing shrinkage, bulk density and ultimate compressive strength tests were performed to determine the most feasible combination of ingredients. Geopolymer samples produced using aluminium powder instead of ball clay were found to be very brittle and unsuitable for refractory service.

Development of dry coal gravity separation techniques

Dry separation method was used at the beginning of 20th century to separate coal separation process. First industrial applications of dry separation took place in the middle of 1930s. At that time air separator Frazer-Yankey, based on aero suspension was used in in Pittsburgh and Lundale, West Wirginia coal preparation plants. Later, some more constructions like RAW air jig, air table “V” type Birtley, air jig type Kirkup, air table “V” type Peale-Davis or air jig type Bruay-Soulary were constructed. Fast development of wet technologies of processes, especially jigging and heavy dense medium separation caused the discontinuation of the further development of dry separation methods and replacement of dry preparation plants with plants based on wet methods of enrichment. At the end of 20th century and beginning of 21st century dry separation method started once again to be widely used in the world. New types of equipment like FGX vibrating air table, TFX air jig or KAT process technology were introduced to wide applications in Asian countries. The paper describes few constructions of old air separators and new ones, used nowadays. It contains comparison of the separation results obtained by means of various equipment and shows possibility to separate coal in laboratory scale air jig.

Substitution of magnetite in dense medium separation by Zinc-Lead waste

Dense Medium (or Heavy Medium) Separation (DMS) is one of the most efficient and commonly used method of separation in different mining branches. Dense Medium for coal processing is based on the suspension of fine and dense material, usually magnetite or ferrosilicon, in water. Magnetite for that purpose is the most commonly used mineral in Polish mines, but has to be entirely imported from abroad. Ferrosilicon, recovered from Zinc-Lead waste could be an alternate to magnetite for use in DMS coal processing. In this study an attempt of recovering that material from “Miasteczko Śląskie” Zinc Plant wastes was made. By simple separation and comminution processes, large amount of magnetic fraction, which could be successfully used in dense medium as the substitution for the magnetite was obtained. Almost 70% of collected waste from lead refining process is proper for the use in the DMS process. Obtained fraction is relatively brittle and easy to grind, which should generate minor costs of production. Almost entire fraction is also highly reactive for magnetic field, which will be helpful in the recovery from dense medium solution, using existing magnetic separators in coal processing plants. Chemical analysis show that concentration of a few metals is significant, which may cause environmental obstacles. But that can also be solved, using simple method of recovery of metal ions from process water.