Ore Comminution Research Articles

Aspects of roller press for the comminution of crushed iron ores

Aspects of roller press for the comminution of crushed iron ores

Evaluation of Ni-Cu Ore from Zapolyarnoe Based on Mineralogical and Physical Properties before and after Comminution

For the effective comminution and subsequent enrichment of mineral ores, comprehensive knowledge of their mineralogical and physical properties is required. Using an integrated methodology, this study evaluated samples of polymetallic Ni-Cu ore from Zapolyarnoe, Russia. Several analytical techniques were utilised, including optical microscopy, microindentation with Vickers geometry, the Point Load Test, and Mineral Liberation Analysis (MLA). The purpose of this study was to determine mineral associations, physical features, and enrichment during jaw crusher comminution. The acquired properties included the Point Load Strength Index, Vickers Hardness Number, and fracture toughness. The MLA method characterised seven fractions in terms of particle size distribution, degree of liberation, association, and modal mineralogy. Magnetite, pyrrhotite, pentlandite, and chalcopyrite were calculated in terms of wt% and their textural features. The enrichment of each ore phase in fractions with particle sizes smaller than 400 µm was determined. The influence of this enrichment was discovered to be correlated with various textural and structural parameters, such as intergrowth, grain size, and crack morphologies after indentations. In addition, the chromium content of magnetite contributed to an increase in the fracture toughness values. Despite the complexities involved, even limited samples of materials provide valuable insights into processing behaviour, emphasising the importance of considering mineralogical parameters in comminution studies.

A Review of the Grinding Media in Ball Mills for Mineral Processing

The ball mill is a rotating cylindrical vessel with grinding media inside, which is responsible for breaking the ore particles. Grinding media play an important role in the comminution of mineral ores in these mills. This work reviews the application of balls in mineral processing as a function of the materials used to manufacture them and the mass loss, as influenced by three basic wear mechanisms: impact, abrasion, and corrosion. The effect of grinding media geometries and density on the mill performance was also reviewed to determine what the research has recommended as the most suitable grinding media for different grinding applications. Although considerable work has been carried out in that area, the influence of grinding media shape on the liberation of minerals, as well as the effect of various mill conditions on the performance of mixed grinding media shapes, are still poorly understood. Thus, the review opens up opportunities for further research to improve the grinding processes, especially considering that even a slight improvement in the process efficiency significantly reduces the production costs.

Influence of ore size on the production of micro-sized ore particles by high-pressure gas rapid unloading

Comminution of ore is a critical and energy-intensive process in mineral resource utilization. High-pressure gas rapid unloading (GRU) has emerged as a promising ore grinding technique, wherein high-pressure gas is injected into the ore and is unloaded at high speed to induce tensile failure inside the ore. Although the GRU is capable to achieve more efficient ore comminution with lower energy consumption compared to conventional methods, it is still in the early stages of development. The pulverization effect of different size ores is a crucial question needing to be revealed before the GRU industrial application. This study explores the impact of ore size on ore pulverization by GRU, using kaolin as an experimental material. Specifically, we discuss the following: 1. the impact of ore size on high-pressure gas infiltration, 2. the effect of infiltration time on ore pulverization, and 3. the effect of ore size on GRU-pulverized ore. The results indicate that the GRU pulverization method is highly applicable to kaolin, and different ore sizes have minimal effects on ore pulverization. Finally, we explain the insignificant size effect of GRU-pulverized ore by discussing the ore material length scale, deformation scale, and ore size. The conclusion may provide a basis for extending the GRU method from the experimental lab scale to a larger one. It may also provide a reference for applying GRU in kaolin comminution.

The effect of high voltage electrical pulses on iron ore comminution to improve desulfurization flotation recovery

The effect of high voltage electrical pulses on iron ore comminution to improve desulfurization flotation recovery

Simulation of Electrical and Thermal Properties of Granite under the Application of Electrical Pulses Using Equivalent Circuit Models.

Since energy efficiency in comminution of ores is as small as 1% using a mechanical crushing process, it is highly demanded to improve its efficiency. Using electrical impulses to selectively liberate valuable minerals from ores can be a solution of this problem. In this work, we developed a simulation method using equivalent circuits of granite to better understand the crushing process with high-voltage (HV) electrical pulses. From our simulation works, we calculated the electric field distributions in granite when an electrical pulse was applied. We also calculated other associated electrical phenomena such as produced heat and temperature changes from the simulation results. A decrease in the electric field was observed in the plagioclase with high electrical conductivity and void space. This suggests that the void volume in each mineral is important in calculating the electrical properties. Our equivalent circuit models considering both the electrical conductivity and dielectric constant of a granite can more accurately represent the electrical properties of granite under HV electric pulse application. These results will help us better understand the liberation of minerals from granite by electric pulse application.

An Investigation into the Influence of α–β Quartz Phase Transition on Banded Iron Ore Comminution

An Investigation into the Influence of α–β Quartz Phase Transition on Banded Iron Ore Comminution

Simulation of the comminution process in a high-speed rotor mill based on the feed’s macroscopic material data

In this paper, we present a method that allows for the quick and efficient simulation of the comminution process in high-speed rotor mills. The method requires only the feed’s macroscopic material data and the geometry of the machine. Consisting of two stages, the method couples Computational Fluid Dynamics (CFD) with the Discrete Element Method (DEM) to obtain the collisional velocities and angles of a representative group of particles passing through the machine. Due to this coupling, any mill which relies on fluid forces acting on the ore particles can be simulated. After obtaining these values, the second stage commences wherein a single ore particle consisting of DEM elements collides against a rigid surface. The data obtained from this stage is then used to determine the minimum required working parameters of the chosen machine to achieve proper ore comminution. The proposed methodology was applied to analyse the novel concept of using beater mills for the comminution of copper ore.

Wear resistance of a Metco 1030A hard coating deposited on Hadfield steel by laser cladding for ore comminution application

The premature wear and/or failure of components and equipment used for ore comminution can result in unscheduled downtime and, therefore, significant losses for the mining industry, in which it is estimated that about half of the total maintenance cost in mining is due to the manufacture of damaged parts and the other half due to downtime and labor. In this sense, approaches to improve the wear resistance of this kind of equipment are of great interest. Therefore, the present work aims to evaluate the potential of coating a high manganese Hadfield steel used to manufacture grinding hammers with Metco 1030A alloy (Fe–C–Mo–V–B) via laser cladding (DED-L). The coatings were deposited on Hadfield steel substrates (cast) using different levels of laser power and scanning speed. The coatings were characterized in relation to the presence of surface and internal defects, morphology, microstructure, chemical composition, and microhardness. The wear resistance of the coatings was evaluated by pin-on-drum tests. For all deposition conditions, continuous tracks were formed. Despite the superficial cracks, the layers did not detach, confirming the metallurgical bond with the substrate. The microstructure of the coatings is typically composed of vanadium carbides (VCs) and molybdenum borides (Mo2B) in a martensitic matrix. For the same scanning speed, carbides and borides tend to become larger and more widely spaced with increasing laser power. Compared with the Hadfield steel substrate, the coatings have significantly higher hardness and wear resistance. Despite the cracks, normally acceptable in the intended application, it can be said that the application of the Metco 1030 alloy via laser cladding has the potential to increase the service life of Hadfield grinding hammers.

Increasing Energy Efficiency and Productivity of the Comminution Process in Tumbling Mills by Indirect Measurements of Internal Dynamics—An Overview

Tumbling mills have been widely implemented in many industrial sectors for the grinding of bulk materials. They have been used for decades in the production of fines and in the final stages of ore comminution, where optimal levels for the enrichment particles’ sizes are obtained. Even though these ubiquitous machines of relatively simple construction have been subjected to extensive studies, the industry still struggles with very low energy efficiency of the comminution process. Moreover, obtaining an optimal size for the grinding product particles is crucial for the effectiveness of the following processes and waste production reduction. New, innovative processing methods and machines are being developed to tackle the problem; however, tumbling mills are still most commonly used in all ranges of the industry. Since heavy equipment retrofitting is the most costly approach, process optimization with dedicated models and control systems is the most preferable solution for energy consumption reduction. While the classic technological measurements in mineral processing are well adopted by the industry, nowadays research focuses on new methods of the mill’s internal dynamics analysis and control. This paper presents a retrospective overview of the existing models of internal load motion, an overview of the innovations in process control, and some recent research and industrial approaches from the energy consumption reduction point of view.

A process mineralogy approach to study the efficiency of milling of molybdenite circuit processing

This study is conducted with the aim of investigating the efficiency of open and closed-circuit molybdenite ore comminution processes (primary and secondary mill, respectively), through mineralogical study of mills feed and product. For this purpose, particle size distribution, minerals distribution, degree of liberation and interlocking of minerals in mills feed and product were studied. According to the results, chalcopyrite, molybdenite, pyrite and covellite constitute the major part of the mineral composition of open-circuit mill feed. Minerals at the mill product, in the order of abundance include liberated molybdenite particles, liberated chalcopyrite and interlocked chalcopyrite with pyrite, liberated and interlocked pyrite particles, and associated silicate gangues. The d50 values of the feed and product particles of the open-circuit mill are equal to 13.80 and 13.40 microns, respectively. Degree of liberation of molybdenite for the feed and product of this mill is almost the same and is equal to 98.0%. Closed-circuit mill feed includes, in order of is abundance, liberated molybdenite particles in the form of blades and irregular polygonal shapes, liberated and interlocked chalcopyrite, and liberated and interlocked pyrite particles with gangue minerals. Molybdenite particles in the mill product are almost completely liberated, and the degree of liberation values of chalcopyrite and pyrite are 84.40% and 91.40%, respectively. According to particles size distribution of the feed (d50 equal to 25.03 microns) and the product (d50 equal to 24.24 microns) of closed-circuit mill, it can be stated that comminution is not well-operated in closed-circuit mill due to the low solid percentage of closed-circuit mill feed and the inefficiency of hydrocyclone. Examination of Mo, Cu, and Fe grade variations for 10 days in both off and on modes of mill shows that closed-circuit mill does not have an impact on comminution process. It can even be concluded that the mill has a destructive effect the flotation process by producing slimes.

Comminution of Copper Ores with the Use of a High-Pressure Water Jet

The article presents research on the comminution of copper ore in a self-constructed mill using high-pressure water jet energy to investigate the usefulness of such a method for comminuting copper ore. As a result, ore particles are obtained that are characterized by appropriate comminution and a significant increase in their specific surface, in turn allowing for potential further processing of the mineral. A comparative analysis of the efficiency of copper ore comminution, primarily taking into account the unit energy consumption and the efficiency of the milling process, clearly indicates that the energy absorption of hydro-jet material comminuting is lower than during mechanical grinding, e.g., in a planetary ball mill. The applicability of the technique depends on the brittle nature of the host rock, e.g., it is especially appropriate for sandstone and shale ores.

Modern trends in the design of comminution processes and equipment for non-ferrous metals ores

When designing new concentrator plants or revamping the existing ones, it is crucial to properly size and design the process equipment and choose the supplier. The comminution circuit is the most power consuming of all the processing stages. A variety of tests are usually performed to determine the physical and mechanical properties of ore, and the results of such tests serve as the basis for comminution circuit equipment sizing. Various computer simulation packages are used to find the best solutions in terms of process equipment and processes. Analysis of the in-house and public databases containing the test data helped obtain new relationships with regard to ore hardness. Having analyzed the public laboratory test data accumulated by Alex Doll, as well as the results of experiments conducted by the ore comminution laboratory of the Minerals Processing Department at Saint-Petersburg Mining University, the authors came up with a modern procedure to examine the physical and mechanical properties of ores for equipment sizing to implement a standard cycle of semi-autogenous grinding with further ball milling. Samples of copper-nickel ores were analyzed in this research study. The results of the analysis served as the basis to estimate the power consumption by the comminution circuit. The resultant figures were compared with the power consumption figures of a functioning concentrator plant that processes the studied copper-nickel ores. The estimated specific power consumption of the SAG mill deviated from the actual power consumption by –6.5%. In the case of the ball mills, the deviation was estimated at +14.4%. The total estimated specific power consumption of the entire comminution circuit exceeded the one of the functioning plant by +7.6%. The described approach is applicable to different comminution circuits, which include crushers, high pressure grinding roll, and tumbling mills. The resultant process parameters are necessary and sufficient for the comminution circuit simulation using the JKSimMet software and for crushing circuit simulation using the discrete element method in the RockyDEM software.This research study was funded by the Russian Foundation for Basic Research (Grant No. 20-55-12002 NNIO_a).

Effects of microwave irradiation on impact comminution and energy absorption of magnetite ore

The severe mechanical wear and high-energy consumption in the comminution process of high hardness iron ore have always restricted the efficient and economic development of an enterprise. On the basis of the basic principle that microwave irradiation can induce rock damage, the magnetic ore specimens were subjected to microwave heating treatment with different heating paths and cooling paths; the uniaxial impact comminution test was conducted by the drop hammer impact equipment. This study analyzed the effect of the heating and cooling paths on the crack propagation process, dynamic mechanical strength, and energy consumption of magnetite ore. The results show that microwave irradiation causes obvious microwave-induced cracks in ore, and in the subsequent impact cracking process, the new cracks gradually penetrate the microwave-induced cracks and form the macroscopic fracture surface. With the increase of irradiation power and time, the ore dynamic strength decreased, and the absorption energy increased. Therefore, increasing the total output energy of microwave can effectively alleviate the mechanical wear and enhance the comminution effect of ores. Among the factors that affect the mechanical properties and absorption energy of ore, power has a higher priority than time. With the increase in the heat exchange rate between the ore and the external environment, the ore comminution becomes more intense, leading to the best comminution effect of ores. The research results have an important reference for the practical application of microwave irradiation technology in hard rock comminution.

Potential Benefits in Copper Sulphides Liberation through Application of HRC Device in Ore Comminution Circuits

The article presents results of investigations on a high-pressure comminution process carried out in the roller press device, aiming at potential improvement of effectiveness of downstream beneficiation operations. The major point of interest of the paper concerned an assessment of the useful mineral liberation in relation to the volume of operating pressing force in the press device. Obtained results of mineral liberation were compared to flotation effects and downstream grinding process in a ball mill. Environmental influence in terms of dust emission was also analysed. The feed material was crushed in the high-pressure roller crusher (HRC) device under four different values of pressing force (Fsp): 3.0, 3.5, 4.0 and 4.5 N/mm2. Each product then underwent the liberation analysis, together with determination the energy savings through calculation of Bond’s working index, flotation recoveries and grinding kinetics. Results of investigations showed that both the most favourable crushing results and mineral liberation level were achieved for the highest values of operational pressing force. Nevertheless, the observed effects were less than linear together with further increasing of Fsp in HRC device. However, the obtained results of investigation unambiguously showed that pressing force affects the obtained crushing results: comminution degrees and flotation recoveries were higher while the duration of downstream grinding operation and grinding energy consumption were lower.

Application of the Cumulative Kinetic Model in the Comminution of Critical Metal Ores

Over the last decades, several reliable mathematical models have been developed for simulating ore comminution processes and determining the Work Index. Since Fred Chester Bond developed the Work Index standard procedure in 1961, numerous attempts have been made to find simpler, faster, and economically more advantageous alternative tests. In this paper, a Bond test simulation based on the cumulative kinetic model (CKM) has been checked on a spreadsheet. The research has been accomplished by conventionally determining the kinetic parameters for some Ag and Au ores and for three pure minerals and one rock that are common constituents of the gangue rock. Analysis of the results obtained allowed to develop a simplified procedure for calculating the kinetic parameters and their application to Work Index determination through simulation.

Methods of Ore Pretreatment for Comminution Energy Reduction

The comminution of ores consumes a high portion of energy. Therefore, different pretreatment methods of ores prior to their comminution are considered to reduce this energy. However, the results of pretreatment methods and their technological development are scattered in literature. Hence, this paper aims at collating the different ore pretreatment methods with their applications and results from published articles, conference proceedings, and verified reports. It was found that pretreatment methods include thermal (via oven, microwave, or radiofrequency), chemical additive, electric, magnetic, ultrasonic, and bio-milling. Results showed that the chemical pretreatment method has been used at an industrial scale since 1930, mainly in cement production. The microwave pretreatment results showed positive improvements at pilot scale mining applications in 2017. The results of ore pretreatment using electric and ultrasonic methods showed up to 24% and 66% improvement in energy consumption, respectively. The former and the latter have been piloted for gold and carbonate ore, respectively. Findings also showed that magnetic, radiofrequency, and bio-milling methods have not led to significant reductions in comminution energy. Based on energy reduction, safety, costs, stage of application, and downstream benefits, microwave and electrical pretreatment methods may be focused for applications in the mining industry.

Exact solutions of population balance equations for breakage and growth processes, using group analysis

Population balance equations have been applied to model a wide range of processes including breakage, crystal nucleation, growth, agglomeration, comminution of ores and other solids, but the lack of exact solutions necessitates the use of numerical methods. A class of population balance equations with time independent but size dependent growth rate and breakage rate is investigated analytically. All invariant solutions, explicit exact solutions, reduced equations and optimal system of subalgebras for the corresponding system of equations are presented in this paper.

Automated SEM Mineral Liberation Analysis (MLA) with Generically Labelled EDX Spectra in the Mineral Processing of Rare Earth Element Ores

Many rare earth element (REE) deposits have experienced multistage geological enrichment processes resulting in REE bearing mineral assemblages of considerable complexity and variability. Automated scanning electron microscopy (SEM) mineral liberation analysis of such REE ores is confronted by the difficult assignment of energy-dispersive X-ray (EDX) spectra to REE mineral names. To overcome and bypass this problem, a generic and reliable labelling of EDX reference spectra obtained from REE-bearing minerals based on their contents of Si, Ca, F and P in a bulk normalised analysis is proposed. The labelled spectra are then combined into groups of REE-P (~monazite), REE-Ca-Si-P (~britholite), REE-Ca-F (~synchysite) and REE-F (~bastnaesite, parisite, fluocerite). Mixed spectra with low counts for REE from minute REE mineral grains are combined into a separate group. This classification scheme is applied to automated SEM mineral liberation analysis (MLA) data from beneficiation products by comminution and multistage flotation of REE carbonatite ores. Mineral modes, mineral grain size distribution, mineral liberation, mineral locking and mineral grade versus recovery curves based on the analysis of >200,000 particles in a sample can be recognised and interpreted in virtual grain size fractions. The approach as proposed here will allow future process mineralogical studies of REE deposits to be robust and comparable.

EFEKTIVITAS PENGGERUSAN BIJIH TIMAH PRIMER MENGGUNAKAN BALL MILL DI PT MENARA CIPTA MULIA DESA SENYUBUK KABUPATEN BELITUNG TIMUR

PT Menara Cipta Mulia is a primary tin mining company. The primary tin ore processing process includes comminution, sizing and concentration activities. The stage of primary tin ore comminution begins with the crushing process using a jaw crusher and then refined using a ball mill again. Ball mill is a form that is used to shrink the grain size of materials to obtain finer materials (fine materials) and preparation of the right size for the concentration process, namely size 60.degree. -200 mesh. Variable ball mill settings that are not appropriate welcome coarse ball mill scouring material (20 s.d. 50 mesh), so we need to do the grinding again because the minerals have not been taken from the impurity minerals. The ineffective process of grinding primary tin ore records high production costs. The experiment was carried out with bait stimulating variables 3-4 TPH, 4-5TPH, and 5-6 TPH. The bait size is 0-2 cm, 0-4 cm and 0-6 cm. The air rate is 4.436 l/h, 7.394 l/h, and 11.091 l/h. The experiment was conducted 27 times with the combined formula for the results of scouring the ball mill. Based on the experiments carried out, the right material for the process of concentration size 60 s.d. Was obtained. -200 mesh, because the size of the mineral has been released from the impurity minerals. The smaller feed bait, bait size, and air flow obtained from the materials resulting from the grinding of ball mill 60 mesh up to -200 mesh height. Effectiveness of grinding get in sample 19 with the highest production value of 5 s.d. 6 TPH. This parameter is used to get the right results for the concentration process, which is 60 mesh size. -200 mesh. The effective value of the feed rate variable 5 d. 6 TPH, feedback size 0-2 cm, and water rate 4.336 l/h.