Gravity Separation Research Articles

Zirconia Enrichment of Zircon from Arikya, Nasarawa State, Nigeria, by Magnetic and Gravity Separation Processes for Use as Reinforcing Agent in Composite Formulation

Acceptable zircon for composite formulation in the aerospace industry requires that the mineral contains a minimum of 65% zirconia (ZrO2). Despite having vast deposits of zircon, Nigeria’s aerospace industry has historically relied primarily on imported mild steel tubes for solid rocket motor cases (SRMCs) construction, resulting in three major challenges: low strength-to-weight ratio, pressure, and temperature containment. In this study, the Arikya zircon deposit located in northern Nigeria was investigated with the aim of upgrading low-grade zircon ore using magnetic and gravity separation processes for use in composite formulation for SRMCs. The dry high-intensity magnetic separator (DHIMS) produced a ZrO2 grade of 52.48%, recovery of 57.99%, and an enrichment ratio of 0.78 with a separation efficiency of 0.56, while the air-floating separator (AFS) generated the highest of 65.52% ZrO2 grade with 70.81% recovery and enrichment ratio of 1.25 with a separation efficiency of 0.25. The ZrO2 content increased from 40.77 to 65.52% after beneficiation. Iron oxide and titanium dioxide contaminants at 0.73 and 0.83% were reduced to 0.66 and 0.54%, respectively, while the specific gravity increased from 4.4 to 4.6 g/cm3. The ZrO2 content and specific gravity were improved to the minimum standard specified for zirconia-reinforced composite application and competed effectively with industrially/globally accepted zircon. These results demonstrated the efficacy of combining DHIMS and AFS to upgrade the low-grade zircon ore from Arikya, Nasarawa State.

Purification and Recovery of Hot-Dip Galvanizing Slag via Supergravity-Induced Cake-Mode Filtration

The elimination and retrieval of slag produced during the hot-dip galvanizing process are crucial in reducing plating defects and enhancing economic efficiency. Hot-dip galvanizing slag can be separated and purified efficiently by using graphite carbon felt filtration in a supergravity field. The effects of the gravity coefficient (G), separation temperature (T), and separation time (t) on the separation efficiency were investigated. Under the optimal conditions as G = 300, T = 460 °C, and t = 120 s, these conditions yielded filtered zinc with 0.022 wt% Fe and 1.097 wt% Al. The separation efficiencies achieved were 87% for the acquisition ratio of filtered zinc (AZn), 93.67% for the recovery ratio of zinc (RZn), and 96.01% for the loss ratio of iron (LFe). Based on these laboratory findings, an amplified centrifugal separation apparatus was conceptually designed for future online separation and recycle of zinc slag on an engineering scale. The filtered zinc obtained from this apparatus contained 0.027 wt% Fe and 1.844 wt% Al, while the recovery ratio of zinc (RZn) and the loss ratio of iron (LFe) achieved 85.97% and 95.47%, respectively.

Reapplication Potential of Historic Pb–Zn Slag with Regard to Zero Waste Principles

Smelting used to be less efficient; therefore, wastes obtained from historical processing at smelter plants usually contain certain quantities of valuable metals. Upon the extraction of useful metal elements, metallurgical slag can be repurposed as an alternative mineral raw material in the building sector. A case study was conducted, which included an investigation of the physico-chemical, mineralogical, and microstructural properties of Pb–Zn slag found at the historic landfill near the Topilnica Veles smelter in North Macedonia. The slag was sampled using drill holes. The mineralogical and microstructural analysis revealed that Pb–Zn slag is a very complex and inhomogeneous alternative raw material with utilizable levels of metals, specifically Pb (2.3 wt.%), Zn (7.1 wt.%), and Ag (27.5 ppm). Crystalline mineral phases of wurtzite, sphalerite, galena, cerussite, akermanite, wüstite, monticellite, franklinite, and zincite were identified in the analyzed samples. The slag’s matrix consisted of alumino-silicates, amorphous silicates, and mixtures of spinel and silicates. Due to the economic potential of Pb, Zn, and Ag extraction, the first stage of reutilization will be to transform metal concentrates into their collective concentrate, from which the maximum amount of these crucial components can be extracted. This procedure will include combination of gravity concentration and separation techniques. The next step is to assess the Pb–Zn slag’s potential applications in civil engineering, based on its mineralogical and physico-mechanical properties. Alumino-silicates present in Pb–Zn slag, which contain high concentrations of SiO2, Al2O3, CaO, and Fe2O3, are suitable for use in cementitious building composites. The goal of this research is to suggest a solution by which to close the circle of slag’s reutilization in terms of zero waste principles. It is therefore critical to thoroughly investigate the material, the established methods and preparation processes, and the ways of concentrating useful components into commercial products.

Gravity Separation Tests of a Complex Rutile Ore

The complex rutile ore containing TiO2 and ZrO2 exhibited a high economical value. To effectively recover TiO2 and ZrO2 from the raw sample, a complete gravity separation process including a spiral chute and a shaking table was proposed. Chemical constituents, phase, liberation degree and size distribution were firstly characterized by XRF, chemical analyses, XRD, EPMA-EDS and screening to understand the mineralogy. Then, two stages of spiral chute separation tests were performed to treat the complex rutile ore. A rough zircon concentrate containing 33.18% ZrO2 was obtained after the first-stage spiral chute and a rough rutile concentrate containing 56.77% TiO2 was obtained after the second-stage spiral chute. To further improve the grade and recovery of ZrO2 and TiO2 in the rough products obtained by spiral chutes, shaking table tests were performed. A zircon concentrate containing 42.65% ZrO2 and a rutile concentrate containing 61.75% TiO2 were obtained. For the tailing of the first-stage spiral chute, a rutile product assaying 57.50% TiO2 was obtained, and the tailing was directly discarded as waste after the shaking table tests. Moreover, the distribution regularities of ZrO2 and TiO2 in the products were further revealed by XRD analyses. Finally, a closed-circuit beneficiation process was proposed to treat the complex rutile ore for achieving comprehensive and effective utilization.

Минералого-геохимические особенности золотосодержащих руд месторождения Пакрут (Центральный Таджикистан) как основа гравитационного обогащения

The mining sector, in particular gold mining, plays an important role in the economy of Tajikistan. Today, the issue of optimizing gold mining mechanisms, increasing its efficiency and expanding the resource base is of topical importance. The depletion of easily accessible gold deposits is stimulating the development of methods for extracting gold from refractory and low-grade ores. One of the promising methods of pre-treatment of such ores is gravity enrichment. The aim of the study is to characterize the Pakrut gold deposit, to determine its mineralogical and chemical composition, and to develop an optimal gravity enrichment scheme for gold recovery. Research objectives are as follows: to study the mineralogical composition and geochemical characteristics of gold-bearing ores, and then to develop a technique for their gravitational enrichment. The object of the study is the gold-bearing ores of the Pakrut deposit (Central Tajikistan). Materials and methods of research: analytical work and enrichment in laboratory conditions were carried out in the chemical laboratory of the Pakrut Joint Venture, the ore enrichment laboratory of the V. I. Nikitin Institute of Chemistry of NANT, the Central Committee of the Main Geological Directorate under the Government of the Republic of Tajikistan. It is found that gold in the Pakrut ores is mainly represented by native gold and electrum. The main gold-bearing minerals are pyrite, arsenopyrite, sphalerite, galena, jamesonite and some vein minerals. The gold content in the ore is about 6 g/t. The granulometric composition of gold is extremely uneven. Most of the gold particles are less than 10 μm in size and are coated with gold-bearing minerals, which hindered their release during grinding. In accordance with the characteristics of the gold deposit, gravity enrichment method has been used to extract the liberated coarse gold. Studies have shown that the gravity separation process is used for the primary processing of ore to recover coarse gold particles. The gold content and recovery in the gravity separation concentrates are 46.58 g/t and 44.59 %, respectively.

Efficiency of preliminary gravity separation of gold-bearing ore from the Malinovka deposit

Efficiency of preliminary gravity separation of gold-bearing ore from the Malinovka deposit

Applicability of Gravity Separation Method on the Ashashire Gold Ore Deposit from Benishangul Gumuz Region, Western Ethiopia

Applicability of Gravity Separation Method on the Ashashire Gold Ore Deposit from Benishangul Gumuz Region, Western Ethiopia

The Analysis of Gas-liquid Separation Technology Research Progress

Gas-liquid separators are commonly utilized in the energy and chemical industries. This paper briefly introduces the separation principles and research progress of the primary gas-liquid separation equipment domestically and internationally. The paper briefly summarizes the working principles of gravity separation, filtration separation, and centrifugal separation equipment. Next, attention is focused on optimizing the separation performance of centrifugal separation equipment, which offers advantages of small size and high separation efficiency. Finally, a comparative analysis of these gas-liquid separators is provided.

Geological investigations and mineralogical characterization of the Awreith Gol Lead-Antimony Deposit, Chitral, Pakistan

Purpose. The importance of mineralogical characterization for complex ore deposits is continuously increasing due to the increasing demand for minerals worldwide. The proper mineral characterization needs to be carried out for selecting appropriate processing technology for the beneficiation of complex ore in order to efficiently obtain ore concentrate according to the market demand. The purpose of this study is to carry out a detail mineral characterization of the complex lead-antimony ore deposit of Chitral, Pakistan, necessary for selecting the most appropriate processing technology and designing a mineral processing plant. Methods. In this research, a preliminary study was conducted on representative samples of complex lead-antimony ore deposits of the Awreith Gol area in Chitral, Pakistan to investigate and characterize the deposit prior to beneficiation, as well as to determine the processing potential of the deposit and to make a further decision on a suitable beneficiation technology. In this regard, thin section of complex ore representative samples was studied using a Scanning Electron Microscope for ore morphology analysis, EDX for chemical composition analysis, and X-ray fluorescence spectrometer analysis. Findings. The ore deposit of the studied area is mainly composed of sedimentary rocks and intrusions of igneous rocks with varying degrees of metamorphism. Geologically, the area is characterized by the Paleozoic-Mesozoic sequence of North Karakorum system and volcano-sedimentary series. The study of mineral characteristics confirms that galena and stibnite are ore minerals containing lead 48.01% and antimony 15.43%. Originality. The geological characteristics of the studied area have been explored. The studied ore consists of lead, antimony, stibnite and galena. The mineral characterization results have revealed that these metals can be extracted economically by selecting an appropriate mineral processing technology. Practical implications. Mineralogical study of the mineral, combined with the chemical analysis of the ore, confirms that the lead-antimony complex ore of Chitral deposit can be beneficiated using relatively cheap gravity separation technology.

Applicability of the Teetered Bed Separator for Beneficiating Indian Iron Ore Fines: An Experimental Study

Higher alumina and lower iron content in Indian iron ore fines is a major problem for its effective utilization in the ironmaking process. India is the second largest steel producer in the world with an annual production of 200 million tons in the year 2020, whereas iron ore beneficiation of this country is highly derisory. Only 52 concentrators are required to produce 220 MTPA of iron ore. Most of the concentrator's benefits are limited to sizing and washing. In recent years, the Teetered Bed Separator (TBS) has gained significant importance and appeared as a viable option for beneficiating a variety of fine minerals. So, a systematic study has been carried out to verify the suitability of the TBS to reduce the alumina content and improve the iron grade in Indian iron ore fines. As the performance of gravity separation processes strongly depends on the feed particle size, a size-by-size beneficiation study was carried out to delineate the role of particle size on the performance of the TBS. Based on this study, the TBS is established to be a possible alternative to the other conventional equipment used for the beneficiation of iron ore fines.

Utilisation of livestock by-products for resource-saving biogas production in industrial pork production

Modern energy systems are complex multi-component systems that use mechanical, thermal, and electrical energy. As fossil fuel reserves decline, interest in renewable energy sources is growing everywhere, which is driving research into biogas production technologies. The purpose of this study was to evaluate technological approaches to reduce resource costs to produce renewable energy sources from organic waste (manure) from pig farms. This study employed the bibliographic method of research, laboratory method, biochemical methods (determination of the chemical composition of manure and wastewater), statistical, mathematical (calculation of economic efficiency), multicriteria analysis, and analytical method. Based on the conducted research, a resource-saving technology for the preparation of wastewater for use in the production of renewable energy in industrial pork production was developed, which ensures a reduction in capital and operating costs for biogas generation. It was found that the settling of the initial wastewater with a moisture content of 96.94±0.18% produces a sediment with a moisture content of 91.23±0.25% and a liquid fraction with a moisture content of 98.86±0.42%. At the same time, the organic matter in the sediment extracted from the original wastewater is about 87%, and in the liquid fraction – about 98% of the dry matter. The technological process includes centrifugal and gravity separation of the initial wastewater into fractions (sediment and liquid fraction), gravitational thickening of the sediment and its dosing for methane digestion to produce biogas. It was shown that the application of the proposed approaches can reduce capital investments by about 30%. Based on the multicriteria analysis, it was found that the proposed biogas production technology has a significant advantage in terms of the complex efficiency indicator of each of the considered options N(Ck) compared to the idealised one. For this technology, the objective function is the smallest according to the criteria considered and amounts to 0.1672, while the objective function of the baseline technology is 1.9 times worse. The findings of the study on the use of livestock by-products for resource-saving biogas production are planned to be used at pork production complexes and farms

Impact of feeding conditions on continuous liquid-liquid gravity separation, part II: Inlet/outlet drop size distribution and fractional separation efficiency

The effect of the feeding conditions and operating temperatures on the separation process was investigated in a continuous gravity-driven separator, following the analysis of the outlet drop size, and formation/shape of dense-packed zone. The inlet and outlet drop size distributions (DSDs) were considered in combination with the separation efficiency. The inlet and outlet DSDs were found to be self-similar across varied feeding conditions and operating temperatures. An increase of operating temperatures from 20 to 40∘C had a tiny impact on the inlet DSDs and resulted in an 1% - 3% increase in separation efficiency but an 8% - 13% reduction in outlet drop size. A novel concept of integrating separation efficiency and DSDs was introduced, allowing for a more comprehensive assessment of the separation process. The fractional separation efficiency was introduced, and it was evaluated based on the self-similarity of inlet and outlet DSDs.

Advances in E-Waste Recycling: Physical and Chemical Treatment Methods

The unprecedented rise in production and consumption of electronic devices has resulted in staggering amounts of electronic waste (e-waste). Improper recycling and disposal of e-waste can cause severe environmental and public health repercussions due to the presence of toxic substances like lead, mercury, and flame retardants. This article introduced advanced e-waste recycling technologies, focusing on physical and chemical treatment methods. Physical treatments such as gravity separation, electrostatic separation, and inverse flotation enable efficient and cost-effective recovery of precious metals like gold, silver, platinum, and rare earth metals from e-waste components. These physical processes are often environmentally friendly, scalable, and can handle diverse e-waste streams. Chemical treatments, including the dimethylformamide technique, supercritical fluid technique, and pyrolysis, allow for separating hazardous substances and recovering valuable materials not amenable to physical processes. Supercritical CO2 fluid destroys toxic organic compounds while enabling metal recovery. Pyrolysis converts plastics into liquid oil and gas products. By enhancing the separation and purification of valued materials, these physical and chemical e-waste recycling techniques provide more profitable, efficient, and sustainable solutions to ever-growing e-waste volumes.

Iron, copper, and rare earth minerals beneficiation in an IOCG type deposit

ABSTRACT The sample of the Sineqan mine (Arak, Iran), containing 16.5% Fe, 0.13% Cu, 475 ppm Ce, 446 ppm La, and 134 ppm Nd, was characterised and processed to investigate the possibility of separating iron, copper, and REE minerals. Microscopic studies showed that the main minerals in the sample include magnetite, hematite, goethite, specularite, pyrite, and chalcopyrite, while the gangue minerals consist of quartz, clay minerals, and carbonate minerals. The results of heavy liquid studies using Bromoform showed that by reducing the particle size from 1180 to 300 micrometre, 76.6% of iron and 72.76% of copper went into the heavy section, while 77.9% of REEs entered the light section. The magnetic separation experiments revealed that higher magnetic field intensity increased the recovery of iron, copper, and REEs with no separation between them. In summary, the results indicate that REEs are primarily present in the light section due to their association with sphene silicate mineral, and gravity separation demonstrated superior performance in terms of both recovery and selectivity. The results of this research are significant for the processing of iron oxide-type deposits that contain copper and REEs.

Tungsten tailings issues and reprocessing solutions

This paper aims to provide an overview of tungsten (W) tailings properties, detrimental impacts of these tailings, approaches to mitigate these impacts, and a presentation of methods to reprocess them to capture their economic value. Since W is widely used in a variety of industries, it has been extensively mined since the 19th century, and the mining continues to generate significant volumes of tailings. Recent data show that global W production stands at 84 kt per year, and more than 100 Mt of W tailings exist containing over 100 kt of WO3. The tailings contain variable amounts of valuable products and deleterious environmental substances. Some of the contained metals are in great demand for the energy transition. However, these tailings usually contain FeS2/Pyrrhotite and FeAsS minerals, which, when exposed to air and water, can produce acid mine drainage. As such, W tailings may pose environmental and human health risks. Globally, the reprocessing of W tailings presents a potential resource that can be regarded as a paradigm of sustainability and circular economy. Flotation, enhanced gravity separation, and wet high-intensity magnetic separation have been reported to be the common approaches to reprocessing W tailings. However, W processing presents particular difficulties owing to complex material properties, such as fine particle size, surface weathering, similarity in surface properties exhibited by gangue materials (fluorite, apatite, calcite), low concentrations of the elements of interest, and poor mineral liberation.

Effect of cleaning, milling, and cooking on the reduction of deoxynivalenol in freshly harvested rice

Abstract Fusarium mycotoxins were frequently present in freshly harvested rice samples caused by Fusarium head blight in China recently. Due to the importance of rice and the risks associated with mycotoxins, the fate of Fusarium mycotoxins in rice was evaluated by physical methods. In the present study, a total of 157 freshly harvested rice samples were collected from fields in Jiangsu Province. Mycotoxin analysis showed that only Fusarium mycotoxins were found in these samples, with deoxynivalenol (DON) being the major mycotoxin. Twenty-three freshly harvested rice samples containing concentrations of DON higher than 200 μg/kg were selected for cleaning and milling. Compared with air or gravity separation, the combined air and gravity separation was the most effective cleaning method to decrease the content of DON. After milling, brown and white rice intended for human consumption presented lower level of DON than freshly harvested rice, husks, and bran. Three types of brown and white rice with different contents of DON were chosen for cooking. Compared with other treatments, preboiled was the most effective method to reduce DON in both brown and white rice. The results of this study improve our understanding of the transfer ratios of DON and the development of effective control measures during the postharvest stage.

Scalable fabrication of a robust asymmetric superwetting Janus mesh by facile spray-coating for oil–water emulsions separation

Janus membrane with asymmetric wettability are emerging separation materials for the purification of emulsified oil–water mixtures, however, their poor mechanical durability and low-flux without external pressure severely limit their practical application. Herein, a robust superwetting Janus mesh demonstrating a high water contact angle (WCA) difference up to 157° was developed by simply spraying on the stainless steel mesh (SSM), via the superhydrophobic fluorocarbon resin/polyvinylidene fluoride/1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane modified titanium dioxide@carboxylated CNTs (FEVE/PVDF/F-TiO2@CNTs) layer and a superhydrophilic layer consisting epoxy resin/ethylene imine polymer/sodium perfluorooctanoate modified bentonite (EP/PEI/F-Bentonite). By carefully adjusting the surface polar-nonpolar molecule repulsion based on the two oppositely bond energy side and incorporating nano/microstructures to form a stable interfacial oiling/hydration layer, the robust Janus mesh achieved interface demulsification and gravity separation of emulsified oil–water mixtures. The prepared Janus SSM exhibited excellent gravity-driven separation performance, achieving a flux up to 1508.6 L m−2h−1 for water-in-oil (W/O) emulsions, and 843.1 L m−2h−1 for oil-in-water (O/W) emulsions. Additionally, it exhibited high separation efficiency with water rejection above 99.9 % and oil rejection above 99.7 %. Moreover, the prepared Janus mesh with fine uniform nano/microstructures and functionalized groups demonstrated notable reusability and mechanochemical stability after 10 cycles of O/W and W/O emulsion filtration, 100 cycles of sandpaper abrasion, and strong acid/alkali immersion for 7 d. Overall, this study expected to facilitate the fabrication of a robust asymmetric superwetting Janus mesh with enhanced separation properties for highly efficient oily wastewater treatment.

Mineralogical factors affecting the separation behavior of Ta-Nb-bearing minerals in the gravity field: mineral grain size, liberation, and association relationship

Gravity separation is the primary method used to beneficiate Ta-Nb-bearing minerals, however, it performs poorly in low-grade and fine-grained ores. A comparative study of gravity separation products (concentrate, middlings, and tailings) reveals the factors affecting the separation behavior of Ta-Nb-bearing minerals in the process combined with a spiral chute and shaking table from the perspective of mineralogy. The results reveal that columbite-tantalite is the principal Ta-Nb-bearing mineral. The grain size of columbite-tantalite in the concentrate is the coarsest, followed by that in the middlings, and the finest in the tailings, which are mainly distributed in the range of -150+38 μm, -75+20 μm, and-38 μm, respectively. The liberation degree of columbite-tantalite in the concentrate and tailings is positively correlated with grinding time, while that in the middlings is negatively correlated with grinding time. The density of columbite-tantalite-bearing particles in concentrate is mainly distributed above 3 or even 4, due to the high liberation degree of the columbite-tantalite in the concentrate, as well as the high amount of rich intergrowth associated with heavy minerals. The density of Ta-Nb-bearing mineral particles in the middlings and tailings is predominantly distributed in D<3. It demonstrates that the liberation degree is not the most essential factor in determining columbite-tantalite separation behavior in the gravity field, and the mineralogical characteristics of columbite-tantalite including grain size, association relationship, and particle density, may be more important. The results of this investigation can provide theoretical support for the strengthening separation of low-grade tantalum-niobium ore.

Farklı İki Metal Grubun Geri Kazanımı İçin Gravite Ayırıcısı Tasarımı

This study, "Design of a Gravity Separator for the Recovery of Two Different Metal Groups", represents important research aiming to recover metals in a sustainable way and reduce the amount of waste. This study aims to separate metals according to their density differences. It is an effective method, especially for the separation of different metals such as copper and aluminum. Therefore, this study investigates how this technology can be used more efficiently.As a result of the literature review, existing gravity separation techniques were evaluated. This formed the basis for a new and novel gravity separator design based on existing knowledge. This design is designed to have a capacity of one ton per hour. This capacity demonstrates usability on an industrial scale. The designed separator aims to separate mixed copper and aluminum pieces and convert them into pure granule raw material.During the implementation phase, it was tested how this design would perform in the field. As a result of these tests, it is aimed to recover approximately 8760 tons of waste material annually. This makes a positive contribution to the environment by recycling large amounts of waste material. In conclusion, this study highlights an important method for sustainable recovery of metals. The effective use of gravity separation technology is of great importance in reducing the amount of waste and protecting natural resources. This study is an important step in highlighting sustainability and environmentally friendly practices.

Recovery of residual carbon from coal gasification fine slag by a combined gravity separation-flotation process

Recovering inner residual carbon is important for fully utilizing coal gasification fine slag (CGFS) resources. In this study, we adopted a combined gravity-separation and flotation process to efficiently recover residual carbon by considering the characteristics of the CGFS and optimizing the operating factors of the process. CGFS is principally a mixture of residual carbon and ash, with low-density particles containing more of the former. Accordingly, residual carbon is preliminarily enriched by gravity separation, in which gas velocity (vg) and water velocity (vw) significantly impact separation efficiency, followed by feed volume (m). The residual carbon in the initial concentrate was preliminarily enriched (i.e., loss on ignition (LOI): 55.90%; combustible recovery (Ro): 72.36%) under appropriate operating conditions (i.e., vw = 0.04 m/s, vg = 3 m/s, m = 150 g). Moreover, the quality of the flotation concentrate was most influenced by collector dosage (mc), followed by aeration rate (η), frother dosage (mf), stirring speed (w), and grinding time (t) during flotation of the primary concentrate. The flotation concentrate exhibited LOI and Ro values of 90.95% and 50.34%, respectively, under the optimal flotation conditions (i.e., mc = 20 kg/t, mf = 15 kg/t, w = 2600 rad/min, η = 200 L/h, t = 360 s); it has a high residual carbon content and is an ideal raw material for preparing fuels or carbon materials.