Modification of strength properties of copper ore as a factor in improving the efficiency of ore preparation processes

This paper presents a comparative analysis of autogenous and media assisted grinding of a manganese ore and copper ore both obtained from Otjihase in Namibia. The objective was to understand the relationship between ore properties and Grindability and thus effectively select comminution circuit and equipment based on this relationship. Laboratory studies were carried out to determine the ease of grinding the ore samples relative to one another. The sample of known weight was crushed and the particles thoroughly homogenized for sieve size analysis and Grindability tests. The Grindability test on each ore was both autogenous and media assisted for dry grinding at -250 microns with constant mill charge of 200 g per run, media charge of 40% by weight and mill operations of 100 to 500 revolutions corresponding to mill speeds of 5 to 25 rpm. The Grindability index of each ore was calculated and compared based on the tests results and used to calculate work indexes for the ores based on the Bond’s model. The autogenous tests produced average Grindability values of 0.55 kg/ton/rev and 0.65 kg/ton/rev for the copper and manganese ores respectively; and media assisted tests gave average values of 0.8 kg/ton/rev and 1.45 kg/ton/rev respectively for the copper and manganese ores. The results show that although media charge grinding produced higher Grindability values, both ores are economically amenable to autogenous grinding which suggests that with proper circuit design, the use of autogenous grinding for these ores (especially the manganese) can save significant cost. The results also show that Grindability increases with mill speed up to an optimum value beyond which grindability decreases with increasing speed and may even drop to zero while mill is running. It is also observed that grindability has close relationship with ore properties especially hardness and compressive strength. It should be noted that the inefficiency factors for the grinding are not considered in these results.

Modification of magnetic properties of siderite ore by microwave energy

The aim of the work is to assess the factors that determine the effectiveness of devices used at different stages of ore processing. The nature of the destruction at each stage is determined by different parameters, therefore, it is so important to search for information factors that allow evaluating the response of mineral raw materials to external influences at the stages of ore preparation. The research methodology is based on the analysis of energy and power factors, which can be correlated both with the loading device and with the body being destroyed. Force factors characterize the response of a material to damaging effects, for example, the limiting amount of resistance to deformation is estimated by the force at which the destruction occurred. The results of the analysis of the role of energy and power factors are given on the example of a selfgrinding mill, a centrifugal crusher, and others. The effectiveness of the self-grinding mill is determined by the ratio of energy and power parameters in the processes of ore lumps kinetic energy conversion into the energy of elastic and breaking strains of the crushable (and crushing) material. It is shown that 88 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 1. 2020 ISSN 0536-1028 the efficiency of centrifugal crushers is ensured by the high intensity of collisions of a multitude of particles, which initially possess excess kinetic energy. In devices such as a roller-press or a cone inertial crusher, the final phase of destruction is associated with volumetric deformation of the layer. This means that the final stages of destruction are completely determined by the structural and strength characteristics of the feedstock and its particle size distribution. The field of application of the presented results are technologies in which the liberation of minerals during ore destruction is considered as a process of structure transformation based on the principles of rational ore preparation. The properties of ores, energy and force factors are important informational parameters of the analysis and selection of methods of destruction during the liberation of minerals. Examples of successful and unsuccessful use of a roller press as a device for reducing the energy consumption for ore preparation are explained within the framework of ideas about the relationship between energy and power factors.

The study on potential-controlled flotation test of differential flotation process was carried out in the light of the change of a certain ore properties. The test used self-developed EMZ-91, as well as conventional collectors of ethyl thio carbamate and butyl xanthate for the flotation of copper, lead and zinc ores respectively, in which the copper sulfate was used as the activator of zinc mineral. The new differential flotation process, which is using lime to regulate pulp potential, produced the copper concentrate grading 27.18% copper at 73.37% recovery, the lead concentrate grading 66.00% lead at 63.00% recovery, and the zinc concentrate grading 55.27% zinc at 87.69% recovery.

The depletion of mining resources forces the mining industry to process more heterogeneous and complex orebodies. The inherent heterogeneity of these orebodies and their relation to processing recoveries have received considerable interest in recent years. The properties of ores, such as mineral composition and association, are known to affect flotation performance. Even ores with similar compositions can vary significantly regarding their texture, where the same minerals can occur in different forms. Therefore, very careful geometallurgical planning is needed to overcome the recovery losses. Glencore’s Mount Isa Copper Operation has reported historical difficulties decreasing the copper losses associated with natural floatable pyrites. Understanding the rock properties of naturally floatable pyrites and how they relate to chalcopyrite losses is crucial for concentrator operations. The Mount Isa geometallurgy team is looking for proxies for predicting copper losses and natural floatable pyrites to improve mine planning. This paper presents an approach for predicting the collector-less flotation of pyrite, as well as chalcopyrite losses from rock properties. The statistical analysis between the rock quality and ore type gives an indication of the chalcopyrite losses and natural floatable pyrites, which has potential use in geometallurgy plans.

To choose the most efficient method and ore beneficiation flow diagram, it is important to know physical and chemical properties of ore concentrates. The feasibility of application of the Cu nuclear magnetic resonance (NMR) method in a local field aimed at studying the properties of copper ore concentrates in the copper–iron–sulfur system is demonstrated. Cu NMR spectrum is measured in a local field for a copper concentrate sample and relaxation parameters (times T and T) are obtained. The spectrum obtained was used to identify a mineral (chalcopyrite) contained in the concentrate. Based on the experimental data, comparative characteristics of natural chalcopyrite and beneficiated copper concentrate are given. The feasibility of application of the NMR method in a local field to explore mineral deposits is analyzed.

The complexity of deep processing of fine-grained and refractory mineral raw materials is determined by the difficulty of disclosing aggregates of ore components during disintegration and extracting them into commercial products of standard quality. The main task of the disintegration of such ores is to destroy the object along the phase boundaries without overgrinding while minimizing energy costs. To implement selective disintegration, a precise study of the properties of the mineral components of the ore is necessary. However, there are no systematic data on the effect and relationship of the mineralogical-technological, structural-textural and physical-technical properties of minerals, rocks and ores with the processes of selective disintegration. The article presents the results of computer microtomographic and optical-microscopic studies of the structural and textural characteristics of typical sulfide copper-nickel ores using a SkyScan-1173 microtomograph from Bruker (Belgium), as well as a specialized, accredited as a measuring tool, Thixomet Pro software (Russia). The studies made it possible to identify automatically 19 morphometric parameters of ore grains in three mutually perpendicular sections, the most informative of which were the grain size of individual ore minerals, their perimeter, distance between grains and grain shape (sphericity, edge roughness, and others). The obtained quantitative characteristics of the structural and textural parameters, the analysis of the granulometric composition of the grains of ore minerals make it possible to assess the possibility of using selective grinding at various stages of ore preparation.

Based on the analysis of the properties of the copper ore from Jinggu area in Yunnan province, a suitable technical route was presented for processing of eligible copper concentrate and the main factors i.e. grinding fineness, Na2S dosage and collector dosage, affecting the quality of roughing concentration was investigated. On this basis, a close-circuit flotation test scheme was preceded, which obtained a high quality copper concentrate with Cu grade of 16.08%, copper recovery of 58.52%. The recovery of copper concentrate is much lower than the Cu recovery of roughing concentrate from the condition experiments. This may be contributed to the fact that fine slime carried by middling worsens the separation of copper minerals and gangues. The Mo was enriched in concentrate, which is significantly considered to recovery in further work.

Ore retention bunkers and receiving bins are important for continuous operation of transport system in a mine. Although the designs of the bins used in the KGHM PM S.A. mines have undergone modifications, their operating principle has remained unchanged since their initial commissioning. Their operation entails many problems, which are caused by the durability and functionality of the entire structure. Preventive actions and research into directions for possible modernizations require the type of damage and its reasons to be identified in the first place. This article presents an evaluation of the documented types of damage and an analysis of the repair works performed for the entire population of the receiving bins operated in one mine. The comparative evaluation of the bin failure rate is here proposed to be performed with the use of a number-based failure indicator and of a mass indicator. The key problem identified in the research was the wear and tear on steel elements due to abrasive processes. The linings of the bin elements were observed to undergo intensive abrasive wear. This abrasive wear of the analyzed bin elements is influenced by a combination of factors, the most important of which include variable physical and mechanical properties of the copper ore.

Chemical looping combustion (CLC) has been validated as one of the most promising technologies for fossil fuel combustion, which can produce high-purity CO2 streams ready for capture and sequestration in power production. The selection of an appropriate oxygen carrier is one of the most important issues for the CLC process, and the reduction kinetics investigation of the oxygen carrier with fuel gas can provide the basis for CLC reactor design and simulation optimization. In this study, copper ore was chosen as an oxygen carrier, and the oxygen release property of copper ore under a nitrogen environment at various temperatures (1073–1193 K) was first investigated in a thermogravimetric analyzer (TGA). Subsequently, the reduction kinetics of copper ore with CO and H2 were evaluated by the TGA at temperatures ranging from 773 K to 1073 K, using a continuous stream of 5, 10, 15, 20, 25, and 30 vol. % of CO or H2 balanced by CO2 or N2. It was found that the reaction rates of these reactions accelerated with the increase in temperature and fuel gas concentration in inlet gas. Both the oxygen release process of copper ore and the reduction process of copper ore with reducing gases can be described by the unreacted shrinking core model (USCM). The reaction mechanism function for the oxygen-releasing and reduction process of copper ore oxygen carrier was varied. The activation energy of the oxygen-releasing process, reduction process with CO, and reduction process with H2 were calculated as 99.35, 5.08, and 4.28 kJ/mol, respectively. The pre-exponential factor ranged from 1.96 × 10−1 to 1.84 × 103. The reaction order depended on the fuel gas, which was 1 and 0.86, respectively, for reaction with CO and H2.

The New Zealand sea sand ore is a kind of vanadia–titania magnetite formed by erosion in the coastal zone. Because of its coarse particle size, smooth spherical particles, complex chemical composition, it has been added to sinter as an auxiliary material. Based on the principle of optimizing ore blending to strengthen advantages and weaken disadvantages, this paper used New Zealand sea sand raw ore that has not undergone any pretreatment as the main material and prepared it into oxidized pellets using a disc pelletizer and explored the influence of high-proportion unground sea sand ore on the preparation process and reduction performance of oxidized pellets. The influence of unground sea sand ore on the falling strength, compressive strength, reduction swelling index, and reduction degree of pellets was analyzed by the ICPAES, XRF, XRD, SEM-EDS, and other detection methods, and the change laws and influencing factors of oxidized pellets were analyzed. With the increase of the amount of unground sea sand ore used, the falling strength and compressive strength of the green pellets first decreased and then gradually increased, while the compressive strength of the oxidized pellets first increased and then decreased. At the same time, as the amount of sea sand ore used increased, the reduction process of pellets was restricted. The reduction swelling index and the reduction degree index generally show a downward trend. However, the compressive strength of the pellets gradually increased after reduction. Through the research on the pellet-forming performance and reduction properties of unground sea sand ore, it is shown that when the amount of unground sea sand ore used was 40%, it can still be used as raw material for blast furnace ironmaking. Thus, this research provided specific data support for iron and steel enterprises to improve the ratio of unground sea sand ore and reduce production cost.

Copper ores are mineral formations of natural origin, the concentration of copper or copper compounds in which is sufficient for their commercial mining. Because of this, copper ores are on the list of minerals that are of strategic importance for the sustainable development of the economy and defense capability of Ukraine. In addition, due to the high thermal conductivity, copper and its alloys are widely used for the manufacture of various types of heat exchangers and radiators. The content of copper in ores usually ranges from 1 to 5%; ores containing less than 0.5% copper are unprofitable for processing at the current level of technology. Mining of copper is of strategic importance, as copper is the main material for the production of cable products and other conductive parts in the electrical industry. The efficiency of technological processes in the mining and industry during the production of copper depends on the quality of ores in relation to the content of minerals that contain copper. Copper ore can be considered a heterogeneous material consisting of two homogeneous phases, one phase is host rock, and the other is copper mineral. Modern image processing techniques have allowed as to automate the identification of minerals in ore samples. Automatic recognition and quantification of minerals using X-Ray tomography, scanning electronic microscope, light microscopy, is one of the most important problems in ore processing systems, as the amount of the minerals in the ore must be determined for further processing. A method of segmentation of colour images of sections of test samples of copper ore is proposed to estimate the percentage content of its components in the section of the tested samples. It is based on the use of chalcopyrite colour features in the HSV model. This colour-based segmentation method is proposed to exploit the average value and distribution of HSV colour components of chalcopyrite in an copper ore image. Segmentation parameters are configured. The experimental results of the segmentation of colour images of copper ore slices by the proposed method are analyzed. The effectiveness of the method is checked using synthesized test images. The method provides an absolute error less than 2.5%.

Graphite ore and graphite tailings were blended into iron-tailings-based cementitious mortars, and their mechanical properties and microstructure were experimentally investigated. The flexural and compressive strengths of the resulting material were tested to compare the effects of graphite ore and graphite tailings as supplementary cementitious materials and fine aggregates on the mechanical properties of iron-tailings-based cementitious mortars. Additionally, their microstructure and hydration products were mainly analyzed using scanning electronic microscope and X-ray powder diffraction techniques. The experimental results showed that the mechanical properties of the mortar material incorporating graphite ore were reduced due to the lubricating properties of graphite ore. As a result, the unhydrated particles and aggregates were not tightly bound to the gel phase, making the direct application of graphite ore in construction materials unfeasible. In the iron-tailings-based cementitious mortars prepared in this work, the optimal incorporation rate of graphite ore as a supplementary cementitious material was 4 wt%. The compressive strength of the optimal mortar test block after 28 days of hydration was 23.21 MPa, and the flexural strength was 7.76 MPa. The mechanical properties of the mortar block were found to be optimal with a graphite-tailings content of 40 wt% and an iron-tailings content of 10 wt%, resulting in a 28-day compressive strength of 48.8 MPa and a flexural strength of 11.7 MPa. By observing the microstructure and XRD pattern of the 28-day hydrated mortar block, it was determined that the hydration products of the mortar with graphite tailings as an aggregate included ettringite, Ca(OH)2, and C-A-S-H gel.

An Approach for Optimizing the Preparation and Production Planning Process in Single Item Production

Observation-informed modeling of artificial neural networks to predict flow and bleeding of cement-based materials