Grinding Product Research Articles

ОПИСАНИЕ ПРОЦЕССА ДВИЖЕНИЯ ЧАСТИЦЫ МАТЕРИАЛА В МЕЖДУРЯДНОМ ПРОСТРАНСТВЕ ДЕЗИНТЕГРАТОРА С ИЗМЕНЯЮЩИМСЯ МЕЖДУРЯДНЫМ РАССТОЯНИЕМ

Currently, disintegrators are one of the types of equipment used for grinding and mixing various materials. The advantages of disintegrators are the ability to control the speed of rotation of the rotors and change the geometric parameters to obtain a grinding product with the desired grain composition, as well as the simplicity of the design. In this paper, as a result of theoretical research, analytical expressions and are obtained, which define the radial size between adjacent rows of impact elements of the grinding chamber with a periodically varying distance. This change in the radial size has a high-frequency character, which determines the destruction of material particles under the influence of tangential stresses arising in them. To perform the necessary transformations, the article presents a design scheme of the disintegrator grinding chamber with a changing radial distance between adjacent rows. In the inter-row space, due to the inequality of the circumferential velocities of moving particles, tangential stresses acting on these particles occur. According to the result of, the value of tangent stresses in the inter-row space depends on the circumferential velocity of the particle, the coefficient of pseudo-viscous flow grinding and the value of the inter-row distance. The value of the row spacing, due to its periodic nature, can be represented as a function of the amplitude of the change in this distance and the angle measured from the initial direction of the axis. By solving a first-order differential equation with separable variables, it is possible to determine the initial and final value of the particle velocity in the region (0 ≤φ≤ /2) of an inter-row space of variable cross-section. The destruction of a material particle in an area with a periodically changing distance will be carried out if the change in the kinetic energy of the particle exceeds the work on its destruction as a result of collision.

Fluidized Bed Jet Milling Process Optimized for Mass and Particle Size with a Fuzzy Logic Approach.

The milling process is a complex phenomenon dependent on various technological and material parameters. The development of a fluidized bed jet milling model is of high practical significance, since milling is utilized in many industries, and its complexity is still not sufficiently recognized. Therefore, this research aims to optimize fluidized bed jet milling with the use of fuzzy logic (FL) based approach as one of the primary artificial intelligence (AI) methods. The developed fuzzy logic model (FLMill) of the investigated process allows it to be described as a non-iterative procedure, over a wide range of operating conditions. Working air pressure, rotational speed of the classifier rotor, and time of conducting the test are considered as inputs, while mass and mean Sauter diameter of the product are defined as outputs. Several triangular and constant linguistic terms are used in the developed FLMill model, which was validated against the experimental data. The optimum working air pressure and the test’s conducting time are 500 kPa and 3000 s, respectively. The optimum rotational speed of the classifier is equal to 50 s−1, considering the mass of the grinding product, and 250 s−1 for the mean Sauter diameter of the product. Such operating parameters allow obtaining 243.3 g of grinding product with the mean Sauter diameter of 11 µm. The research proved that the use of fuzzy logic modeling as a computer-based technique of solving mechanical engineering problems allows effective optimization of the fluidized bed jet milling process.

Synthesis and Properties of Silicon-Carbide-Modified Porous Glass Composite

The synthesis and properties of a porous glass composite obtained, based on cullet powder using aluminum powder and liquid glass, at temperatures not exceeding 100°C are discussed. It is shown that silicon carbide or a mixture of silicon carbide with gallium arsenide, which is a product of grinding in the semiconductor industry, can be used as a composition modifier. It is shown that porous glass composite with density not exceeding 600 kg/m3 and strength in compression not less than 1.7 MPa can be obtained by introducing 32% waste into the composition. The introduction of modifiers promotes better foaming and positively impacts the structural quality factor of the material. The results of these studies expand the range of application and the raw material base for the production of porous glass composites.

Influence of the metal chips disintegration method on the physical and mechanical properties of metal powders obtained

This paper presents the results obtained in comparative grinding studies of alloy metal chips using a ball mill and a vibrating mill. A comparison of the effective viscosity, bulk and tapped density in narrow size classes demonstrated higher rheological properties of the vibration grinding product and significant differences in the distribution of indicators by the size classes, depending on the grinding method. The specific yield and energy consumption indicators were established, which confirmed the superiority of vibration grinding over ball mill grinding. A visual assessment of the shape and surface condition of the ground particles is presented, conducted using a scanning electron microscope.

An Investigation into the Effects of Grinding Media on Grinding Products Characteristics and Flotation Performance of Pyrite

ABSTRACT During the grinding of pyrite, the grinding medium affects the properties of the grinding products, which in turn affects its flotation performance. In this study, we investigated the effects of cast iron ball (CIB) and ceramic ball (CB) grinding media on the grinding products characteristics and flotation performance of pyrite using atomic absorption spectrometry, scanning electron microscopy combined with energy dispersive spectrometry, X-ray photoelectron spectroscopy, contact angle measurement, and single mineral flotation analysis. The results showed that the Fe3+ and SO4 2- concentrations and pH value of the pulp were significantly lower in the case of grinding with the CB medium than with the CIB medium, whereas the dissolved oxygen content of the pulp was significantly higher. The surfaces of the pyrite samples produced by the CB grinding medium were relatively even and smooth with a small amount of formation and coverage of FeOOH as compared to those of the pyrite samples produced by the CIB grinding medium, resulting in a superior hydrophobicity and floatability. Resultantly, the pyrite samples obtained using the CB grinding medium exhibited better performance in flotation recovery than those obtained using the CIB grinding medium. The presence of ferric ions was adverse to pyrite flotation because of the formation of ferric hydroxyl complex. CB shows great potential to be used as grinding medium for pyrite.

Dynamic Rounding Stability in Through-Feed Centerless Grinding

The through-feed method in centerless grinding allows manufacturers to produce cylindrical parts at much higher levels of productivity than can be achieved with in-feed grinding, so it has been extensively employed in industry. However, its rounding mechanism is not yet well understood due to the complexity of the through-feed process. This paper presents the fundamental parameters, such as material removal rates, forces, and so on in the through-feed grinding, and analyses on the grinding system with feedback loops, including regenerative functions and the machine dynamic functions. Further, the characteristic roots of the system, representing the number of waves and the growth rates of the harmonics in roundness, are identified at each grinding position from entry to exit. To evaluate the grinding process stability, a rounding stability index (RSI) was proposed. It was demonstrated that the analytical tool modeled in this paper can identify the optimum operational conditions by the RSI for achieving desired grinding productivity and accuracy. Finally, the model is verified with grinding tests, and the nm-order roundness obtained by the tests is shown.

Effect of dissociation size on flotation behavior of waste printed circuit boards

Flotation is an effective method for recovering metals from dissociated waste printed circuit boards (WPCBs). The difference in dissociation and flotation behaviors of various size particles are revealed in this study. The metal and impurity in 3–1 mm particles were first dissociated under the impact force. The particle morphology of each size particle in the grinding products was analyzed by scanning electron microscope (SEM). SEM results show that the metal particles presents flake shape, and the dissociated glass fiber shows rod shape. The size composition and element distribution appear bimodal distribution. Flotation results present that the distribution rate of particles in floats increases with the decrease of particle size, and increases with the increase of collector dosage. In addition, the removal rate of Si and Cu reveals the same trend. The finer particles are more sensitive to the change of collector dosage. The removal rates of Si in 1–0.25, 0.25–0.074 and −0.074 mm reaches 59.80%, 95.69% and 95.59% with 4 kg/t collector. Under the action of the collector, the floatability of Cu particles with organic matter adhered to the surface is enhanced, which results in the higher impurity removal and Cu loss.

Effect of calcination temperature on the structure and properties of SiO2 microspheres/nano-TiO2 composites

The silica microspheres surface-coated nano-TiO2 composite material (MS-SiO2/TiO2) was prepared by co-grinding the silica microspheres (MS-SiO2) and nano titanium dioxide soliquid (nano-TiO2-sol) in a stirring mill, and then calcining the above grinding products. The photocatalytic performance (methyl orange as the target pollutant) and surface photoinduced hydrophilicity of MS-SiO2/TiO2 calcined at different temperatures were tested, and their structure and morphology were characterized. The calcination temperature has a great effect on the structure and properties of MS-SiO2/TiO2 composites. The composite particles calcined at 300 °C (MS-SiO2/TiO2-300) have low photocatalytic efficiency because they are aggregated seriously and the crystalline phase of TiO2 in MS-SiO2/TiO2-300 has not formed. While, the MS-SiO2/TiO2-500 composite particles showed a good separation state. The TiO2 particles on MS-SiO2 were single anatase phase, and its particle size was about 10–20 nm, exhibiting a well dispersion state. The degradation rate of MS-SiO2/TiO2-500 under 90 min ultraviolet irradiation was 92%, and the water contact angle was 10°, which was better than pure nano-TiO2. In MS-SiO2/TiO2, the reduction of TiO2 particles aggregation, improvement of dispersion and the presence of a single anatase phase were important factors for MS-SiO2 to exert a synergistic effect, which led to the enhancement of nano-TiO2 functional efficiency.

Analysis of the grain market in Ukraine and directions for the development of logistics for the transportation of grain cargo

Grain logistics in Ukraine is actively developing, and therefore needs to study the problems of grain infrastructure and transport and logistics in supply chains. The analysis of the dynamics of grain production volumes indicates their increase during 2010-2019. An analysis of the dynamics of the volume of transportation of grain and grinding products by rail indicates a trend towards a dynamic increase in transportation volumes in 2010-2019. However, the level of logistics efficiency does not correspond to a significant growth rate of grain production volumes, and consequently, an increase in their transportation volumes with subsequent transshipment in ports. The consequence of this is the high cost of Ukrainian grain, and, consequently, a decrease in its competitiveness in the foreign market.Deficiencies in the process of organizing the transportation of grain cargoes by rail to ports were identified and recommendations were made on improving the efficiency of organizing the supply of grain goods from supplier to consumer.

Enhancing the capacity of large-scale ball mill through process and equipment optimization: An industrial test verification

The production capacity of the large-scale ball mill in the concentrator is a crucial factor affecting the subsequent separation and the economic benefits of the operation. The main aim of this study is to improve the processing capacity of the large-scale ball mill. Taking a Φ5.49 × 8.83 m ball mill as the research object, the reason for the low processing capacity of the ball mill was explored via process mineralogy, physicochemical analysis, workshop process investigation, and the power consumption method. Based on this framework, a series of laboratory grinding optimization tests were conducted and verified via industrial tests. The results show that the ore primarily contained hematite and magnetite, the disseminated particle size of magnetite was primarily a coarse-grained inlay that was easy to separate from gangue, while the disseminated particle size of hematite was primarily an uneven and medium-sized inlay, which increased the grinding difficulty. Under optimum conditions of +6.0 mm material suitable for a 100 mm ball diameter, −6.0 + 2.0 mm material suitable for an 80 mm ball diameter, −2.0 mm material suitable for a 70 mm ball diameter; medium ratio of Φ90 mm 34.62%, Φ70 mm 26.92%, Φ60 mm 23.08%, Φ40 mm 15.38%; filling ratio of 32%; material ball ratio of 1.0; rotation speed rate of 80%; and grinding concentration of 78%, the −0.074 mm content in the grinding product increased from 55.10% to 58.86% and the processing capacity of the ball mill increased from 310 to 320 t/h to 350 t/h. Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDS) micrograph analysis shows that the fineness of the ore and dissociation degree of useful minerals were apparently improved by optimizing the process and equipment.

Mesoscale Particle Size Predictive Model for Operational Optimal Control of Bauxite Ore Grinding Process

This article investigates the use of a mesoscale kinetic model to cooperate with the operational optimal control of bauxite ore grinding process. In this article, we propose a new modeling framework where a discretized distributed parameter macroscale model and a mesoscale kinetic model are combined to predict the grinding product particle size. The mesoscale kinetic method does not need an explicit model of the process because it describes the process as a stochastic process. However, the high computational demand has prevented the kinetic model from using an online setting. We overcome this problem by embedding an acceleration algorithm based on the τ-leap method. The proposed model is validated using experimental data. Finally, a solution of the bauxite ore grinding operational optimal control is proposed and the cooperation of the predictive model with other modular is demonstrated.

ОПИСАНИЕ ПРОЦЕССА ИСТЕЧЕНИЯ ДВУХФАЗНОЙ СРЕДЫ ИЗ КАМЕРЫ ПОМОЛА ДЕЗИНТЕГРАТОРА В ПЛОСКОСТИ, ПЕРПЕНДИКУЛЯРНОЙ ОСИ ВРАЩЕНИЯ РОТОРОВ

Currently, disintegrators are equipment used for grinding and mixing various materials. The ad-vantages of disintegrators are the ability to control the rotation frequency of the rotors and change the geometric parameters to obtain a grinding product with the required grain composition, as well as the simplicity of the design. This article describes the flow of a two-phase medium from the grinding chamber to the outlet pipe, whose axis is shifted relative to the plane passing through the center of rotation of the rotors. A design scheme for the two-phase flow into the outlet pipe in a plane perpen-dicular to the axis of the cylindrical body is presented. It is assumed that the movement of the two-phase medium from the grinding chamber to the outlet pipe occurs at a constant modulus speed. The diagram of the two-phase flow is considered taking into account that the length of the outlet pipe sig-nificantly exceeds its width. The relations determining the change of the velocity vector components near the two-phase flow outlet to the outlet pipe are obtained. Based on the obtained expressions, the trajectory of the two-phase flow from the grinding chamber to the outlet pipe is determined. Thus, us-ing the results of this theoretical study, it is possible to provide a rational ratio of the main design pa-rameters of the disintegrator unloading unit.

Extreme Learning Machine Soft-Sensor Model With Different Activation Functions on Grinding Process Optimized by Improved Black Hole Algorithm

Aiming at predicting the key economic and technical indicators (Granularity and Ore content)in the grinding production process, the extreme learning machine (ELM) soft-sensor model with different activation functions on grinding process optimized by improved black hole (BH) algorithm was proposed. Based on the selected auxiliary variables for the soft-sensor model of the grinding, the KPCA method is used to reduce the dimensionality of the high-dimensional data. In order to investigate the influence of different activation functions on the prediction accuracy of the ELM model, seven continuous function (Arctan, Hardim, Morlet, ReLu, Sigma, Sin and Tanh) are used as the activation function of the ELM neural network to establish soft-sensor models respectively. For the shortcomings that ELM model weights and offset values are arbitrarily given so as to result in the low prediction accuracy and low reliability, an improved BH algorithm based on the golden sine operator and the Levy flight operator (GSLBH) was used to optimize the parameters of the ELM neural network. Simulation results show that the model has better generalization and prediction accuracy, and can meet the real-time control requirements of the grinding process.

A Study on Productivity Improvement for the SKD11 Steel Grinding by Using CBN Grinding Wheel - A New Approach

This paper presents a new approach to improve the machining productivity when grinding the SKD11 steel by using CBN grinding wheel. This approach based on the satisfaction of the surface roughness requirement. The grinding experiments were carried out according to Box-Behnken plan by using the CBN grinding wheel, HY-180x13x31.75-100#. The experimental data was used to build a regression function of the surface roughness depending of the cutting parameters in grinding process including the workpiece velocity, radial feed rate, and depth of cut. The effect degree of each cutting parameter on the surface roughness was also determined. And then, a new solution was proposed to improve the grinding productivity by increasing the workpiece velocity with the satisfaction of the surface roughness requirement. The proposed solution was verified by experimental research. The analyzed results showed that the workpiece velocity can be increased about 1.7 times to increase the machining productivity while the surface roughness only changed about 0.14μm.

Информационные системы оценки технологических достоинств пшеницы

В практике пищевой промышленности востребованы высокоточные и экспрессные методики определения технологических качеств пшеницы и прогнозировании будущих потребительских свойств продуктов ее переработки. Перспективным является использование для этих целей комплексного показателя твердозерности, однако на сегодняшний день его определение сопряжено с низкой точностью, высокими трудозатратами, использованием дорогостоящего инструментария. Целесообразны разработки автоматизированных систем анализа размолотого зерна в помольных линиях на мукомольных предприятиях. Такие системы могут использоваться для определения целевого назначения производимой муки. В статье описана автоматизированная система оценки технологических свойств продуктов переработки зерна в процессе помола. В основе системы лежат методики формирования данных о форме и размерах частиц в потоках размола зерна. Для этого производимые цифровой камерой Sony IMX219 микроснимки частиц размола зерна подвергались обработке микрокомпьютером Raspberry Pi 3 разработанным программным обеспечением на основе библиотеки алгоритмов компьютерного зрения OpenCV. Для реализации работы такой системы в помольных линиях производства была сконструирована лабораторная установка. Поскольку для успешного анализа частиц компьютерным зрением необходимо устранение эффекта слипания частиц, пользовались для этой цели совместным влиянием электростатических полей и вибрации. Оптимальные технические параметры подобраны опытным путем - электрическое напряжение около 24 кВ и частота вибраций анализируемых образцов размола зерна муки около 45 Гц. Для получения высокого напряжения использовался генератор коротких импульсов на основе высокочастотных тиристоров ТЧ63. Меняя напряжение питания генератора можно плавно менять напряжение на выходе от 1 до 35 кВ. Один вывод высоковольтного источника питания заземлен, второй вывод подключен к датчику-регистратору частиц размола. Разработан алгоритм оценки твердозерности пшеницы на основе данных о форме и размерах частиц в потоках размола зерна – построено соответствующее регрессионное уравнение. Для оценки точности алгоритма сравнивали результаты оценки твердозерности образцов зерна с референтным методом – по показателю микротвердости - способности зерна сопротивляться деформации (вдавливанию). Микротвердость зерна оценивали на микротвердомере ПМТ-3 с квадратной пирамидкой. Установленные эмпирические зависимости позволяют производить оценку твердозерности зерна - с точностью не менее 3 %. Благодаря экспрессности такой оценки технологических свойств продуктов переработки зерна, имеется возможность вмешаться в процесс помола и скорректировать его для повышения эффективности.

ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ СТРУМИННОГО ПОДРІБНЕННЯ НА ОСНОВІ АКУСТИЧНОГО МОНІТОРИНГУ ПРОЦЕСУ

Мета. Метою роботи є розробка шляхів підвищення ефективності струминного подрібнення на основі встановлення зв’язку продуктивності млина та якості продукту з характеристиками акустичних сигналів.Методика. Оптимізація процесу струминного подрібнення виконувалась з використанням аналізу акустичних сигналів робочих зон струминного млина. Для побудови залежностей технологічних і акустичних параметрів було використано статистичний аналіз експериментальних даних.Результати. Дослідження підтвердили залежність параметрів акустичних сигналів робочих зон від режиму подрібнення. Встановлено, що зміни максимальної і середньої амплітуди акустичних сигналів робочої зони в процесі подрібнення мають чітко виражений коливальний характер, що пов’язано зі зміною циркуляційного навантаження в робочій зоні. Показано, що відносна продуктивність млина, нормована рівнем завантаження камери подрібнення, змінюється в процесі подрібнення за квадратичним законом. В той же час, зміна максимальної і середньої амплітуди акустичних сигналів робочої зони в процесі подрібнення описується поліномом 4 порядку, при цьому величина середньої амплітуди акустичних сигналів робочої зони подрібнення в сталому режимі процесу є квадратичною функцією від відносної продуктивності за рівнем завантаження. Показано, що амплітуда акустичних сигналів характерної частоти, записаних в зоні за класифікатором, прямо пропорційна крупності часток готового продукту, що транспортується.Наукова новизна. Вперше науково обґрунтовано і експериментально підтверджено, що продуктивність струминного млина за рівнем завантаження матеріалом змінюється в процесі подрібнення за квадратичним законом. А залежність амплітуд акустичних сигналів зони подрібнення від відносної продуктивності носить поліноміальний характер.Практична цінність. Встановлення нових залежностей характеристик акустичних сигналів від технологічних параметрів дозволить підвищить ефективність струминного подрібнення на основі результатів акустичного моніторингу. Контроль продуктивності млина та якості продукції за величиною середньої амплітуди акустичних сигналів в робочих зонах установки дасть змогу знизити витрати енергії в технологічних процесах подрібнення для одержання тонкого і надтонкого матеріалу.

КИНЕТИКА РАЗРУШЕНИЯ ЧАСТИЦ МАТЕРИАЛА В ДЕЗИНТЕГРАТОРЕ В РАМКАХ СТАТИСТИЧЕСКОГО ПОДХОДА

Disintegrators are one of the types of equipment that has the ability to combine grinding, mixing and activation of materials of medium strength and hardness. The advantages of disintegrators are the ability to integrate into existing technological schemes and obtain a grinding product with a given particle size distribution, as well as the simplicity of the design. This article analyzes the kinetics of particle destruction in the inter-row spaces of the disintegrator grinding chamber. A diagram of the disintegrator grinding chamber is presented. The mathematical description of impact destruction of particles in the grinding chamber is considered in the framework of the inhomogeneous Markov process. An equation is presented that describes the change in the statistical quantity m (t) - the mathematical expectation. It has been suggested that the intensity of the Markov process ( ) is proportional to the frequency (ω) of rotor rotation multiplied by the time function f (t). This functional dependence is determined from the condition of the same interaction time 0 of the material particle in the inter-row spaces of the grinding chamber. If we assume that the probability of destruction of the particles of the material in the interaction with each shock element is constant, then the mathematical expectation value m (t) will be proportional to the number of particles n (t). The resulting relation (11) determines the law of change in the number of particles during the passage of each row of shock elements. The article derived formulas for determining the change in the number of particles in each inter-row space of the grinding chamber. The obtained relations (24) and (25) describe the kinetics of grinding material particles in the grinding chamber of the disintegrator in the framework of the statistical approach and make it possible to determine the relationship between the size of the initial particles and the size of the grinding product.

A novel crushing pretreatment：Inhibitory effect for micro-fine grinding products of China copper ore based on high voltage pulse

In this paper, a novel crushing pretreatment: the inhibitory effect for micro-fine particles of China copper ore was investigated based on high voltage pulse. The ore structural weakening performance, inhibitory effect, size-reduction energy intervals, energy efficiency were determined. The results show that the main size-reduction energy interval is affected by voltage, and the interval is 3–4kWh/t at 150kV. The pretreatment effect of HVP was improved with an increase in energy consumption, and the maximum grinding index was 1.28at 90kV and 4kWh/t. The content of −74 μm product is 72.91% for pretreated ore compared with 57.16% for untreated ores. The inhibitory effect can be reflected on the contents of micro-fine particles. The ratio of −45 μm in −74 μm product decreases from 71.29% to 53.52% for untreated and treated ores and the inhibitory index is 0.24. The inhibitory effect for micro-fine particles can be effectively achieved by electrical pretreatment.

Effects of grinding media on grinding products and flotation performance of chalcopyrite

Selective flotation has been considered the most promising strategy for treating chalcopyrite. Grinding, an essential procedure before flotation, has extraordinary significance in chalcopyrite flotation. In this study, the differences between the properties of the products obtained by grinding with cast iron ball (CIB, >3.5% C) and ceramic ball (CB, >90% Al2O3) media were investigated using various techniques: atomic absorption spectrometry, scanning electron microscopy combined with energy dispersive spectrometry, X-ray photoelectron spectroscopy, and contact angle and zeta potential measurements. The performance of chalcopyrite flotation was used as the final factor in determining the characteristics of both the grinding media. The results indicate that the Fe3+ concentration and the pH of the pulp obtained by grinding with CB medium were lower, while the dissolved oxygen content was obviously higher, than those of the pulp obtained by grinding with CIB medium. The Cu2+ concentrations were basically the same under the two grinding media systems. Furthermore, grinding with CB medium yielded products with relatively more even and smoother surface than grinding with CIB medium did. Fewer oxygen-containing floccules, i.e., FeOOH and Cu(OH)2, had formed and scattered on the chalcopyrite surface during grinding with CB medium, and this is mainly attributable to the limited local cell reaction of chalcopyrite alone. Additionally, it was found that better hydrophobicity and a lower iso-electric point of the chalcopyrite surface were achieved by grinding with CB medium. Consequently, grinding with CB medium exhibited better performance in terms of chalcopyrite recovery, which was approximately 16% higher than that obtained by grinding with CIB medium.

The effect of degree of liberation on copper recovery from copper-pyrite ore by flotation

ABSTRACT Flotation of grinding products with 55, 60, 65, 70, and 75% of grain size <74 μm, was conducted at the pulp’s pH values of 10 and 12. Higher copper recovery was obtained in concentrates at pH 10, but with lower copper grades, approximately 2%. Copper recovery in concentrates at pH 12 was slightly less, but copper grades were much higher. The effect of grinding was higher at pH 12, especially in terms of copper grades in concentrates, which declined with the increase of grinding time. Ore microscopy tests were done on the concentrates with 55 and 75% of grain size <74 μm at pH 10 and 12. All particles of copper minerals were divided by grain size fractions and by the degree of liberation. Analysis have shown that degree of liberation was higher in finer grinding products.