Ore Recovery Research Articles

A zero-carbon emission approach for the reduction of refractory iron ores: Mineral phase, magnetic property and surface transformation in hydrogen system

In this study, a feasible strategy, named hydrogen mineral phase transformation (HMPT) technology, is proposed and employed to achieve efficient and clean recovery of Hainan Shilu refractory iron ore (HSRIO). The influences of HMPT roasting temperature, roasting time, and H2 concentration on the separation index of HSRIO are investigated. Under the optimal experimental conditions, the iron concentrate grade increases from 62.5% to 67.9%, and the iron recovery increases from 65.0% to 94.7% compared with the original beneficiation process. In addition, the evolution of mineral phases, magnetic properties, and mineral microstructures is analyzed using XRD, VSM, SEM, and high-temperature hot-stage microscopy. It is revealed that the transformation of hematite to magnetite occurs during the HMPT process, with the newly formed magnetite exhibiting a loose and porous reticulation structure. This study is of guiding significance for the development of Hainan Shilu refractory iron ore with high efficiency and zero-carbon emission.

Integration of experimental study and neural network modeling for estimating iron recovery in Davis tube tests

Magnetic separation is a common procedure for the enrichment of magnetic iron ores. Davis tube (DT) test is a standard laboratory technique used to determine the optimum magnetic recovery of iron ore using wet low-intensity magnetic separators. However, the DT test is time-consuming and labour-intensive. In this study, based on the results of DT-tests, generalized regression (GRNN) and radial basis function (RBF) neural networks were developed to predict iron recovery through the Fe and FeO content of the feed. First, the DT tests were performed on 613 iron ore samples with varying Fe and FeO content. Then, neural networks were used to model the iron recovery from the DT test, using the Fe and FeO content of the feed as input data. The modeling results showed that GRNN is a better model for predicting iron recovery. The main statistical metrics indicated that GRNN has AAPRE, RMSE, and R2 values of 3.929%, 2.804, and 0.976 respectively for a total of 613 data points. Moreover, sensitivity analysis demonstrated that iron recovery is directly influenced by both Fe and FeO contents, with FeO content having a more pronounced effect. Finally, Leverage analysis showed that GRNN is highly reliable for predicting iron recovery, with only 2.77% of data points flagged as suspicious based on outlier estimation.

Variations in Temperature and Pressure in the “Reservoir–Well” System Triggered by Blasting Recovery of Iron Ore at the Kursk Magnetic Anomaly

This paper presents the results of precise measurements of temperature and pore pressure in the “reservoir–well” system during the development of iron ore deposits of the Kursk Magnetic Anomaly (KMA) via blasting. For the observation period from October 2021 to June 2024, variations in compressibility, permeability and temperature in the upper Albian-Cenomanian confined aquifer, which is used for district water supply, were determined. The general trend in a decrease in water temperature was traced (from 12 °C to 11.4 °C). It was accompanied by an increase in the hydrostatic head (from 3.7 m to 7.4 m). Water temperature in the upper aquifer was measured for 9 industrial explosions in the mine and for 30 explosions in the quarry. For one explosion in the mine and five explosions in the quarry the coseismic changes in water temperature with amplitudes of 0.06–0.09 °C were established, while changes in pore pressure in the “reservoir–well” system were 0.4–2.2 kPa. Local changes in the permeability of the reservoir in the vicinity of the well (the skin effect) are considered to be the main factor that controls the coseismic response of temperature during industrial explosions. As the reservoir permeability increases, the water temperature in the “reservoir–well” system can decrease and vice versa. The same pattern was observed according to regime measurements performed in 2022–2023. The recorded coseismic responses of water temperature in the upper aquifer in the high-frequency range are similar to the effects observed during propagation of seismic waves originated from earthquakes in the low-frequency range at different sites all over the world for the seismic energy density of 0.05–0.45 J/m3. The observed variations in aquifer temperature in the “reservoir–well” system under episodic dynamic impacts are of particular interest from the point of view of activating hydrogeochemical processes that accompany the development of iron ore deposits.

A Study on the efficiency of organic activator application to process refractory hard-to-beneficiate raw materials

Polymetallic ores with complex mineralogical compositions pose significant challenges in flotation beneficiation, often resulting in suboptimal separation and recovery of valuable minerals. This study aims to analyse the effectiveness of alkyl benzene sulfonic acid (ABSA) as a frothing activator in improving the flotation performance and mineral recovery of polymetallic ore. It presents the results of flotation beneficiation experiments for polymetallic ore of complex mineralogical composition. Experiments were conducted on polymetallic ore samples using ABSA as the frothing activator in the flotation process. The performance was evaluated based on recovery rates and separation efficiency, comparing the results with standard floating frothing agents. The findings showed the highest efficiency of ABSA application for samples of mixed-type ores in increasing the recovery of gold, copper, zinc and lead in the collective concentrates of flotation beneficiation. ABSA activator promotes additional cleaning of fragments containing valuable metals from oxide films and coatings and the transfer of valuable metals' microparticles due to the organics' adsorption properties and the formation of metal-carbon bonds. Another effect of using this reagent is there was an increase in concentrate mass yield while maintaining the quality parameters. A similar effect was observed for beneficiation of copper ore with complex composition - copper recovery in the main concentrate increased. Selective flotation with the development of gold concentrate from hard-to-beneficiate polymetallic ore also showed a significant increase in gold recovery with ABSA pretreatment.

Enhanced recovery of low-grade copper ore and associated precious metals from iron tailings: A case study in China

In the processing of copper and precious metal recovery in a mine in Chengde, Hebei Province, the decrease in copper mineral content and finer grain size distribution of the selected ores have caused challenges in the existing milling process. This has led to difficulties in achieving significant dissociation of chalcopyrite, resulting in decreased separation efficiency of copper and associated precious metals. Particularly, there is a notable loss of precious metals in the flotation tailings. Using BPMA and other detection equipment, the occurrence state, distribution patterns, and liberation degree of copper and associated precious metals in iron tailings were investigated. Subsequent flotation experiments examined the impact of grinding regimes on mineral liberation and reagent regimes on mineral enrichment. Subsequently, flotation experiments were conducted to examine the influence of grinding regimes on mineral liberation and reagent regimes on mineral enrichment. The research findings revealed that copper and precious metal contents in iron tailings are extremely low and finely disseminated within gangue minerals, posing challenges for liberation. Under the optimal conditions determined from flotation experiments, a laboratory closed-circuit process consisting of one rougher, one scavenger, and two cleaner stages yielded a copper concentrate with a grade of 11.33 %, a recovery efficiency of 66.95 %, and containing 9.42 g/t gold, 52.72 g/t silver, 2.78 g/t platinum, and 8.46 g/t palladium. The SEM-EDS analysis further emphasizes the necessity to tailor grinding and flotation processes to optimize the liberation and subsequent recovery of these valuable minerals, avoiding excessive grinding of gangue minerals which could negatively impact flotation performance.

Ultimate Pit Limit Optimization Method with Integrated Consideration of Ecological Cost, Slope Safety and Benefits: A Case Study of Heishan Open Pit Coal Mine

The ecological impacts of mining and the instability of slopes are the key factors restricting the safe, efficient, and low-carbon production of open-pit mines. This study focused on the ultimate pit limit (UPL) optimization under the concept of sustainability by integrating consideration of the economic benefit, ecological impact, and slope geometry. The integrated UPL optimization model based on the floating cone method was proposed by establishing a quantitative model for ecological impacts arising from open-pit coal mining in arid or semi-arid weak ecological land and a cost calculation model of slope reinforcement based on the Monte Carlo method. The case study revealed that steepening the slope angle of given regions resulted in random variations in the quantity of ore rock and the limit morphology. There was an average economic profit rise of USD 9.54M with every 1° increase in slope angle, but the probability of slope instability and the reinforcement cost grows exponentially. In the arid or semi-arid weak ecological land, the ecological costs exceeded 20% of the mines’ average pure economic gains. The proposed optimization method contributes to obtaining an integrated optimal UPL, improving the benefits and the ore recovery rate.

Sulphate-temperature-time interactions and their influence on rheological characteristics of cemented paste backfill

Cement paste backfill (CPB) can provide social and economic benefits such as treating mine waste, preventing surface settlement, providing a safe working platform in underground mines and improving ore recovery. Rheological properties (including yield stress and viscosity) are key factors influencing the ability of CPB to be successfully transported into specified mine stopes. However, no study has been carried out to comprehensively examine the rheological properties of CPB under the combined effects of sulfate, temperature and time. This study was therefore carried out to evaluate the yield stress and viscosity of CPB samples with different sulfate contents (0 ppm, 5000 ppm, 15,000 ppm and 25,000 ppm), exposed to different temperatures (2 °C, 20 °C and 35 °C) and subjected to different curing or transport times (0, 20 min., 1 h and 2 h). Additional measurements, such as TG/DTG, pH, zeta potential and EC monitoring, were also carried out. It was found that CPB viscosity increased significantly with the simultaneous increase in sulfate, time and temperature, and that yield stress also increased, but at a relatively limited rate. There was competition between the yield stress-reducing factor (e.g. sulfate) and the increasing factors (temperature, time). Higher temperatures had a compensatory or counterbalancing effect on the reduction in CPB yield stress caused by the addition of sulfate. It was also found that the significant increase in viscosity was due to the combined effect of a greater number of ettringite crystals generated by the addition of sulfate and a greater number of hydration products produced by higher temperature and/or longer time. The results of this research will be useful for the efficient design of a long-distance transport system for CPB in mines located in permafrost and/or warm regions, in deep mines as well as for CPB containing sulfate.

Towards a Sustainable and Enhanced Iron Ore Recovery: Bio-beneficiation Review

Towards a Sustainable and Enhanced Iron Ore Recovery: Bio-beneficiation Review

Immobilisation of chromium in magnesium carbonate minerals

AbstractHexavalent chromium (Cr6+) is a toxic carcinogenic pollutant that might be released by the mining and processing of ultramafic rocks and nickel laterites and which requires permanent removal from the contaminated biosphere. Ultramafic material can also serve as a feedstock for the sequestration of CO2 resulting from the growth of new minerals, raising the intriguing proposition of integrated sequestration of both pollutants, CO2 and chromium, into magnesium carbonates. Such a synergistic process downstream of ore recovery and mineral processing could be an elegant proposition for more sustainable utilisation and management of the Earth's resources. We have therefore carried out an experimental and microanalytical study to investigate potentially suitable carbonate minerals. Uptake of chromium in carbonate phases was determined, followed by identification of the crystalline phases and characterisation of the local structural environment around the incorporated chromium centres. The results suggest that neither nesquehonite nor hydromagnesite have the structural capacity to incorporate Cr6+ or Cr3+ significantly at room temperature. We therefore propose that further research into this technology should focus on laboratory assessments of other phases, such as layered double hyroxides, that have a natural structural capacity to uptake both chromium and CO2.

Improvements in Rock Mass Description for Stope Design by Geophysical and Geochemical Methods

Stope design is an important part of mine planning, and it aims to balance ore recovery, ore dilution, and production costs without compromising the safety aspects. This paper summarizes the main results from the research, which aims to introduce new techniques to describe the ore body and surrounding rock mass at the tunnel face prior to stope excavation. The research comprises a literature review and a survey among mining professionals to assess current stope design practices. The study identifies geotechnical data, software improvements, and integration of design into mine planning as the most critical areas for improvement. The empirical part of the study proposes new techniques for fast data acquisition. The laser-induced breakdown spectrometry (LIBS) technique is developed for measurements at the tunnel face and from core boxes to provide mineralogical and geometallurgical data. Ground-penetrating radar (GPR) studies are conducted to improve discontinuity characterization, and rapid photogrammetric methods are proposed for efficient tunnel geometry characterization. The techniques discussed in this paper already have many industrial applications. This study reveals their potential to be adopted and further developed to serve ore and rock mass characterization for stope design.

Utilization of Waste Straw Biomass in Suspension Magnetization Roasting of Refractory Iron Ore: Iron Recovery, Gas Analysis and Roasted Product Characterization

The straw-type biomass, as a green and alternative reductant for the suspension magnetization roasting (SMR) of iron ores, is proposed. The roasted products are investigated at a roasting temperature of 750 °C, the roasting time of 7.5 min and the biomass dose of 25%. The iron phase results indicate that hematite ores were reduced to magnetite by the biomass, and the magnetization transformation increased from 0.64 A·m2·g−1 to 36.93 A·m2·g−1. The iron ore microstructure evolutions of holes and fissures are detected by SEM-EDS. The biomass pyrolyzed to form CO2, CO, CH4, H2O, H2, C=O, benzene skeleton, C-Hand C-O compounds at 200–450 °C, while the mass loss of the magnetization roasting process occurred at 450–750 °C by using TG-FTIR. The GC/MS results showed that the organic gases preferred to produce the O-heterocycles at 329 °C while the hydrocarbons were dominant at the high temperature of 820 °C for the hematite ore and biomass mixture. The gas composition analysis explained that the reducing gaseous products (CO, CH4 and H2) were used as a reductant and consumed obviously by hematite ore in the SMR process. The innovative utilization of biomass waste was effective for iron recovery of hematite ore and contributes to the reduction of greenhouse gases and the protection of the environment.

Novel insights into the microstructure of Al-BHA on the surface of ilmenite

In the process of flotation recovery of metal oxide ore, the complexes obtained by premixing metal ions with benzohydroxamic acid are often used as collectors. The study of aluminum (III) -benzohydroxamic acid (Al-BHA) system is not perfect. In order to study the chemical properties, microstructure and adsorption mechanism of Al-BHA on mineral surface, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and density functional theory (DFT) were used. The analysis of FTIR confirmed the chemisorption of Al-BHA onto the ilmenite. AFM results show that the coverage of Al-BHA on the surface of ilmenite is obviously better than that of BHA. According to Fukui function and frontier orbital theory, the chemical activities of Al-BHA are greater than those of BHA. In addition, aluminum atom is the active center of Al-BHA. The bonding model of the collector and (104) ilmenite surface showed that the vacuum adsorption energy of Al-BHA was higher than that of BHA, and the bridge site adsorption form is the most stable. Overall, it is possible to apply Al-BHA with higher activity to ilmenite flotation.

Effect of calcium ions on the surface properties of heterogenite and conducive to sulfidization flotation: Insight from oxygen vacancy

It is challenging to obtain a satisfactory sulfidization effect via direct sulfidization of heterogenite, and the introduction of Ca2+ to modify the surface property of heterogenite could improve its sulfidization. Tests using ICP-OES and SEM-EDS showed that Ca2+ modified the surface morphology of heterogenite, facilitating sulfur ion adsorption. FT-IR and Raman spectrometer analysis revealed that the pre-treatment of Ca2+ was beneficial to form more Co-S bonds on the surface of heterogenite. XPS analysis indicated that Ca2+ modified heterogenite surface properties by creating more oxygen vacancies, which was further supported by EPR test results. DFT calculations further show that oxygen vacancies could increase the adsorption capacity of Co sites on the heterogenite surface. Furthermore, micro-flotation tests showed that the surface modification of Ca2+ could significantly improve the sulfidization flotation recovery of heterogenite. This study found calcium ions enhance the sulfidization of heterogenite by inducing surface oxygen vacancies, which provides a new perspective for understanding and enhancing the sulfidization process of heterogenite and contributes to the efficient recovery of cobalt oxide ore.

Implementation of Sodium Hydrosulfate (NaHS) Flotation with F83 and F515 on Mass Recovery of Gold Ore

Implementation of Sodium Hydrosulfate (NaHS) Flotation with F83 and F515 on Mass Recovery of Gold Ore

A comprehensive assessment on sludge conditioning by pyrite acid eluent-activated peroxymonosulfate based on dewaterability, heavy metals risk and ore recovery

Wastewater activated sludge (WAS) has poor dewaterability and contains heavy metals (HMs), limiting its land application. Therefore, in this study, a novel pyrite acid eluent-activated peroxymonosulfate (Fe2+pyrite/PMS) conditioning approach that can completely recover the residual pyrite and greatly reduce acid use was developed to improve WAS dewaterability, and the HMs chemical speciation and risks of conditioned WAS were assessed. Our results showed that under the optimized operational parameters, the capillary suction time (CST) and water content (Wc) of WAS decreased by 46.03% and 7.75%, respectively. Furthermore, during Fe2+pyrite/PMS conditioning processing, sulfate radical (SO4−) destroyed the extracellular polymeric substances (EPS) matrix, causing bound water release and the decrease of proteins/polysaccharides in outer layered EPS, even the decomposition of some protein-N in tightly bound EPS (TB-EPS) into inorganic-N. In addition, although the total concentration of HMs in the conditioned WAS matrix increased, the Ni concentration decreased in the solid fraction. Further, the risk assessment code (RAC) levels did not increase, and the eco-toxicity of Cr became weakened after Fe2+pyrite/PMS conditioning. However, after acid extraction, the pyrite residue had worsened recycle performance because the passivation layer contained S0/Sn2− on its surface, and no additional elements were detected in the pyrite residue, which had almost no effect on its further usage.

Study on condition prediction and influencing factors of manganese carbonate recovery by high gradient pulse magnetic separation

Manganese carbonate ore belongs to weakly magnetic minerals, and its co-associated minerals are mainly non-magnetic minerals, which can be separated from gangue minerals at high magnetic field intensity. However, manganese grade and recovery of magnetic separation concentrate of manganese carbonate ore are low in actual production. Therefore, the influences of manganese carbonate particle size, magnetic field intensity, volume susceptibility, pulse stroke, pH, and other factors were studied. The optimal test conditions for manganese carbonate ore recovery by high-gradient magnetic separation were predicted through the calculation results. The results show that the particle radius of manganese carbonate is 0.020 mm, the pulse impulse time is 200 r/min, and the magnetic field intensity is 0.9 T. The optimum condition test was carried out with Qianbei manganese carbonate ore as the material. The test results show that the optimum conditions are the particle radius of 0.074-0.019 mm, pulse impulse time of 200 r/min, and magnetic field intensity of 1.2 T. The reason for the deviation is that the actual ore has a fine distribution particle size, many associative bodies, complex composition, and serious agglomeration, resulting in variable particle volume susceptibility. The capture yield increases with the increase of magnetic field intensity and volume susceptibility but decreases with the increase of pulse. The lower the surface potential of manganese carbonate, the higher the recovery of manganese carbonate. The grade of manganese concentrate was 19.06% and the recovery was 76.85%. Mixed manganese concentrate with a grade of 18.04% and recovery of 87.14% was obtained by adding drugs and changing the grinding method.

Lost-ore mining—A supplementary mining method to sublevel caving

Sublevel caving (SLC) is a mass mining method having high productivity and high safety. However, this method often causes a considerable amount of permanent ore loss. Interestingly, all lost ores are buried in the broken waste rocks that come mostly from the caved hanging wall and partly from the ore body in which ore and waste rock are originally situated together. To mine out such lost ores from the broken waste rocks and increase ore recovery in SLC mines, a new mining method called lost-ore mining is introduced as a supplementary method to SLC, and a simple mechanics analysis is used to explain why the lost-ore could be mined out. Using this lost ore mining method, the Malmberget mine had recovered 7.5 million tons of lost iron ores from many old production drifts, as reported in the year 2016. Similarly, the Kiruna mine had mined out 2.6 million tons of iron ores from the old production drifts, according to a report in 2012. At last, some suggestions on how to use this new method are proposed.

Comprehensive Recovery of a High-sulfur Copper-gold Ore in Shandong

The raw gold grade of a mine in Shandong is 1.42 g/t, and it is accompanied by copper and sulfur minerals, and the embedding is closely related, so it is difficult to obtain the ideal index using the original flotation process. In order to realize the effective recovery of gold, copper, and sulfur, the test study of mixing-separation flotation and priority flotation is carried out. The results show that the mineral is more suitable for the beneficiation process of mixing-separation flotation. The recovery rate of gold, copper, and sulfur is 70.42%, 93.58%, and 68.85%, and the recovery rate is 22.89% higher than the priority flotation. The produced copper and gold mixed concentrate and sulfur concentrate can be directly sold to realize the effective recovery of gold, copper, and sulfur.

Mine Design of Laterite Nickel Ore Based on Pit Limit Optimization with Floating Cone Method at Meranti Pit of PT Ang and Fang Brother

PT Ang and Fang Brother Site Lalampu is a nickel laterite mines company located at Lalampu Village, Morowali Regency, Central Sulawesi Province. The purpose of research is to determine the ultimate pit limit using floating cone method and calculate the net present value (NPV), to design the ultimate pit limit at Front 8 of Meranti Pit (one of the company’s fronts), to calculate the mined laterite nickel reserves and the overburden based on the pit design. The data used are block model data, topography, capital and operating costs, commodity price, density, geotechnical data, mine recovery 85%, cut-off grade 1.3%, and the company's production target of 50,000 tons/month. Data processing generates Pit Shell 9 as the ultimate pit limit with ore recovery of 264,375 tons from 284,063 tons of Front 8 resources. Based on the design using Micromine 2021 software with an area of 5.25 hectares, a total of 234,142 tons laterite nickel ore obtained by stripping 389,063 BCM of the overburden, and it still economical with stripping ratio value (1.66 BCM/ton), smaller than the BESR value (6.32 BCM/ton). The amount of nickel laterite reserves produced based on mine recovery of 85% is 199,021 tons so the life of mine lasted 3.98 months.

Rapid detection of molybdenum ore grade based on visible-infrared spectroscopy and MTSVD-TGJO-ELM

The rapid determination of ore grade can improve the efficiency of beneficiation. The existing molybdenum ore grade determination methods lag behind the beneficiation work. Therefore, this paper proposes a method based on a combination of Visible-infrared spectroscopy and machine learning to rapidly determine molybdenum ore grade. Firstly, 128 molybdenum ores were collected as spectral test samples to obtain spectral data. Then 13 latent variables were extracted from the 973 spectral features using partial least square. The Durbin-Watson test and the runs test were used to detect the partial residual plots and augmented partial residual plots of LV1 and LV2 to determine the non-linear relationship between spectral signal and molybdenum content. Extreme Learning Machine (ELM) was used instead of linear modeling methods to model the grade of molybdenum ores because of the non-linear behavior of the spectral data. In this paper, the Golden Jackal Optimization of adaptive T-distribution was used to optimize the parameters of the ELM to solve the problem of unreasonable parameters. Aiming at solving ill-posed problems by ELM, this paper decomposes the ELM output matrix by using the improved truncated singular value decomposition. Finally, this paper proposes an extreme learning machine method based on a modified truncated singular value decomposition and a Golden Jackal Optimization of adaptive T-distribution (MTSVD-TGJO-ELM). Compared with other classical machine learning algorithms, MTSVD-TGJO-ELM has the highest accuracy. This provides a new method for rapid detection of ore grade in the mining process and facilitates accurate beneficiation of molybdenum ores to improve ore recovery rate.