Spiral Classifier Research Articles

Cathodic Protection System of the Spiral Classifier at the KGHM Polska Miedź S.A. Ore Concentration Plant—Case Study of Commissioning and Control of Operating Parameters

The project involved designing, constructing and commissioning a cathodic protection system for a selected spiral classifier operating at the KGHM Polska Miedź S.A. Ore Concentration Plant (O/ZWR). The authors developed a concept and assumptions regarding the corrosion protection of a large industrial device using a cathodic protection system with an external power source. Pre-project studies included conducting a trial polarization of one of the 28 classifiers operating at O/ZWR. The obtained results enabled the determination of the protective current demand required and the selection of a target polarization device, ensuring the flow of current with an intensity that guarantees that the required corrosion protection level will be achieved. The ultimately installed cathodic protection system consisted of an external cathodic protection current source with maximum output parameters of 50V/20A, a power supply system and a polarization anode system. Elements for monitoring corrosion occurring during system operation were installed, which employed reference electrodes of zinc (Zn) and silver chloride (Ag/AgCl) to measure the potential of the structure under cathodic protection. Furthermore, resistive corrosion sensors were installed to measure the steel corrosion rate under polarization conditions, making it possible to assess the effectiveness of the protection. The system will also be equipped with a prototype system for remote monitoring of the operation of the protection system, enabling online observation and analysis of settings and temporary indicators influencing the ongoing corrosion processes.

Enhanced gravity closed spiral classifier: Experimental investigation

Traditional gravity classifiers that leverage differential settling velocities in the gravitational field are bulky and ineffective for particles less than 150 μm. In this study, a newly introduced compact enhanced gravity Closed Spiral Classifier (CSC) is tested experimentally for the classification of slurries containing silica or iron ore fines. The device exploits the differential settling experienced by the particles that are carried by a fluid flowing through a closed rectangular spiral channel. The centrifugal acceleration that is much greater than acceleration due to earth’s gravity enhances the particle classification. Many experiments were conducted using a 3D printed CSC to study the effects of solid system, particle loading, feed flow rate, number of turns and splitter location on the performance of the classifier. Regression models for key performance characteristics are built using the experimental observations to aid in the scale-up and design studies. The equipment is explored to a limited extent for its ability to separate desired and undesired minerals in the iron-ore fines exploiting the density differences.

Advantages of selective grinding using high-pressure grinding rolls combined with air classification

It is well known that the use of high-pressure grinding rolls (HPGR) in crushing circuits improves subsequent power consumption through the output of finer material: the yield of fine fractions in the HPGR product is higher than that in the product of traditional crushers (including third and even fourth stage crushing). It has been established that the use of screens in HPGR circuits is inadvisable and would limit the circuit capacity due to lower friction and the fact that screen performance depends on the size of the finished product. In addition, the use of water (its availability and cost) for spiral classifiers, screens, or hydrocyclones remains a major problem in the industry. The alternative option involving air classification has been used in the cement industry for several decades to separate material fractions in the size range of 0.01–1.0 mm, but has yet to find its way to mineral processing plants. It has been shown that volumetric fracturing in HPGR improves subsequent selective separation. Adequate distribution of the ore components in air classifiers allows the separation boundary to be optimized. The expediency of using HPGR in combination with air classification has been substantiated as it allows, in some cases, to eliminate subsequent ball grinding at industrial plants. This is revolutionizing the ore preparation process. The authors are grateful to Köppern for their research support.The work was carried out with the support of the Russian Foundation for Basic Research (project No. 20-55-12002).

Analysis of the Possibility of Using New Types of Protective Coatings and Abrasion-Resistant Linings under the Operating Conditions of the Spiral Classifier at KGHM Polska Miedź S.A. Ore Concentration Plant

A study was carried out to select the appropriate coatings for corrosion protection of the spiral classifier working at KGHM Polska Miedź S.A. Ore Concentration Plant. The abrasion resistance of selected protective coatings and wear-resistant linings was investigated using a DT-523 rotary abrasion tester with Taber CS-10 rubber abrasive discs. The average weight loss of the coatings after a cycle of 2000 revolutions was determined. Tests of protective coatings using the electrochemical impedance spectroscopy (EIS) technique were carried out to determine the suitability of coatings in the highly saline environment of the aqueous suspension of ground copper ore. During the measurements, changes in resistance, polarising current and capacitance were determined as a function of time for the tested coatings. The linings selected on the basis of laboratory tests were also tested under industrial conditions. Their degrees of wear were characterised. The results obtained indicated the highest abrasion resistance of materials from the polyolefin group (polyethylenes), where the average weight loss did not exceed 5 g/dm2. In the case of protective coatings, the highest durability was demonstrated by coatings with additives of ceramic aggregates, phenol-epoxy, and an elastomeric coating based on polyurea, whose average weight loss during the test cycle did not exceed 19 g/dm2. EIS measurements showed that the tested coatings were resistant to the aggressive environment of the feedstock. Tests under cathodic polarisation conditions of the samples at a potential below the protection potential showed that they were resistant to a highly saline environment and were also resistant to its alkalinisation resulting from the application of cathodic protection, which will be used to protect the classifier together with protective coatings. Tests carried out under industrial conditions using wear-resistant linings made of plastics have made it possible to analyse the mechanism and degree of wear of the various materials during the operation of the classifier. Measurements of lining wear were made in relation to baseline volumes. Polyurethane, a polymer lining based on MDI and PTMG, and those made of ultra-high-molecular-weight polyethylene with anti-stick additives showed the lowest wear rates.

Elaboration and implementation technology of concentration of Magnitogorsk steel-works slime tailings

The problems of processing iron ore tailings of wet concentration plants and wastes with high content of iron, contaminated by oil products are actual from both points of view of ecology and economy. One of the reasons restraining solving the problem is absence of technologies ensuring to involve such wastes into industrial turnover. In the process` of the research, composition and opening degree of ore and non-metallic minerals of concentration slime tailing of Magnitogorsk steel-works (MMK) were studied and technology of their concentration was elaborated. Taking into consideration the contamination of initial slime tailings of MMK, it was proposed to accomplish their preliminary de-sliming to remove vegetable remains and clay slimes by disintegration in a screw-toothed crusher and washing in a spiral classifier. Results of wet magnetic separation (WMS) of the initial slime tailings of MMK, made at JSC “Uralmekhanobr” presented, the slimes having natural coarseness of –2.0+0.0 mm. It was established that WMS at the magnetic field intensity of 1500 Oe ensures effective removal of magnetite, aggregates magnetite-hematite-goetite into magnetic product. Iron content in the magnetite concentrate was varying from 61.5 to 62.6%. For processing of slime tailings of MMK, magnetic separation was proposed by high-gradient magnetic separator with permanent magnets, created specially for these purposes by “ERGA” company. To increase iron extraction degree, it was proposed to apply gravitation methods of concentration of nonmagnetic product, obtained at high-gradient WMS. It enabled to increase iron content in the final magnetite-hematite concentrate up to 59%. A technological diagram of oiled slimes processing presented. Tests with oiled slimes of bottom deposits of metallurgical production under pilot-industrial conditions of MMK exhibited a possibility to obtain additional iron concentrate with total iron content of 62.47% while oil content in it was less 0.3%.

Application of control units VAZM-2U in ore grinding

This paper considers the results of research work aimed at developing control systems to control ore grinding processes that would be compatible with the control unit VAZM-2U developed by Soyuztsvetmetavtomatika. The underlying principle concerning the unit is that grinding of ores with different mineralogical compositions is governed by the same common regularities in correlation between the physical processes that develop in grinding circuits and the defining process parameters. A grinding mill is fed with ore that has varying physical and mechanical properties, and this can lead to accumulation of material in the mill. Indicators of the probable overload condition include mill vibration level and active power draw of the mill drive motor. The point at which the overload condition has arrived is determined by analyzing active power draw and reverse vibration trends. It is demonstrated that a mill overload condition may take place in those time intervals when both the vibration level and the active power draw of the mill motor fall. In this case the VAZM-2U unit calculates a correction command for the ore flow rate regulator, and this way the overload condition is overcome while the ore feed rate returns to the initial value. The VAZM-2U unit can also help reach the maximum output of the overflow product from a spiral classifier avoiding overgrinding, with the finest material being monitored. The unit can also determine the underflow flow rate in the spiral classifier while adjusting this parameter within a given range of allowable values. The underflow flow rate is estimated with the help of an adaptive mathematical model, which can be utilized in closed-loop grinding circuits that include classifiers. The ore grinding control algorithms implemented in the VAZM-2U unit can be modified to be applicable for milling and flotation control.

Comparative Cleaning Stages in Recovery of Copper and Cobalt from Tailings using Potassium Amylxanthate as Collector

Copper and cobalt demand is projected to be increased from here to 2050 and the challenge is to find treat economically minerals which contains those metals. Several tailings from oxide ores throughout the word contain good grades of copper and cobalt that should be recovered by froth flotation. This paper investigates the recovery of copper and cobalt through reprocessing of spiral classifier tailings by determination of specific reagents dosage. The flotation behaviours of malachite and heterogenite were studied through many roughing and cleaning flotation tests in order to recovery most of copper and cobalt. The effect of specific reagents was be varied and others parameters were kept constant. The highest recoveries of both copper and cobalt in rougher concentrate were respectively 82.51% and 72.51% with grades of 12.52% and 0.99% respectively. However, the cleaner concentrate was 24.54 Cu% and 1.38% Co with recoveries of 69.26 % and 40.7% respectively. It was concluded that the reprocessing of spiral classifier tailings through froth flotation is benefit because it recovers most of desired metal and reduces the risk of their presence on environment through.

Comparative Cleaning Stages in Recovery of Copper and Cobalt from Tailings using Potassium Amylxanthate as Collector

Copper and cobalt demand is projected to be increased from here to 2050 and the challenge is to find treat economically minerals which contains those metals. Several tailings from oxide ores throughout the word contain good grades of copper and cobalt that should be recovered by froth flotation. This paper investigates the recovery of copper and cobalt through reprocessing of spiral classifier tailings by determination of specific reagents dosage. The flotation behaviours of malachite and heterogenite were studied through many roughing and cleaning flotation tests in order to recovery most of copper and cobalt. The effect of specific reagents was be varied and others parameters were kept constant. The highest recoveries of both copper and cobalt in rougher concentrate were respectively 82.51% and 72.51% with grades of 12.52% and 0.99% respectively. However, the cleaner concentrate was 24.54 Cu% and 1.38% Co with recoveries of 69.26 % and 40.7% respectively. It was concluded that the reprocessing of spiral classifier tailings through froth flotation is benefit because it recovers most of desired metal and reduces the risk of their presence on environment through.

Hydraulic separation in spiral classifiers. Part 1. Theoretical justification for a mathematical model compiling

Hydraulic separation in spiral classifiers. Part 1. Theoretical justification for a mathematical model compiling

Система автоматичного регулювання співвідношення тверде/рідке в млинах з циркулюючим навантаженням

The operation of a ball mill operating in a closed loop with a spiral classifier depends on the vacuum of the pulp in it, which is characterized by a solid / liquid ratio. Supply to the entrance of the ball mill at the same time ore and sand classifier, as well as changes in the circulating load in a wide range greatly complicate the definition of this technological parameter. This situation has led to the fact that the solid / liquid ratio in mills operating in such conditions can not be automatically adjusted, in turn, the deviation of the pulp vacuum from the required value leads to significant losses. The study of the ball mill as a controlled object on the pulp vacuum channel made it possible to describe it using the mathematical expression given in the article. The solution of this expression makes it possible to characterize the change in the mass of the material in the mill over time, provided that a stepwise action is introduced at the entrance - the volume flow of water or ore. A constant value of the mass of material in the mill will clearly characterize the corresponding solid/liquid ratio. It has been found that it is important to study the filtering capabilities of the control object, as control actions on water and disturbing actions on ore can significantly change the vacuum of the pulp in some areas of the mill. The filtering capabilities of the mill can be investigated by its amplitude frequency characteristics, which showed that at low circular frequencies the amplitude frequency characteristics depend on the mode of operation of the mill - the magnitude of the circulating load and the cost of the source ore. Using computer technology, spatial diagrams of the relative oscillations of the mass of material in the mill from the amplitude and frequency of influences at its entrance through the ore and water. In the course of theoretical research it was determined that the only approach to ensure the required accuracy of determining the solid / liquid ratio in these conditions is to filter the signals before applying to the input of the identification unit of the ratio. Thus, the system of automatic control of the solid/liquid ratio at the entrance to the mill is implemented on microprocessor means. Its operation on the laboratory test bench made on the microcontroller showed high accuracy of stabilization of technological parameter, reliability in various conditions of change of characteristics of input signals.

Study of Suitable Washing Flowsheets For High Ash Coals of Nui Hong Coal Mine

Current high ash coal stockpile of Nui Hong Coal Mine is estimated at about 1 million tonnes. This increasingly stockpiled coal is not sellable and disposable due to the government regulations so that a problem related to space and environment limitations becomes more serious. This report presents the results of the study on washability of Nui Hong high ash coals and proposed suitable flowsheets for washing this type of coals. Basic characteristics of the coals include High ash content of over 55%; High moisture of above 20%, high rate of disintegration into finer particles in water, the high proportion of fine coals of the size fraction 0–6 mm; 30% or more of high ash superfine fraction -0.045 mm that contained mainly slime, clay and fine non-coal organic impurities. The results of particle size analysis and sink-and-float analysis of +1 mm coal sizes indicated that a 1–6 mm clean coal with ash content of less than 45% could be produced by a combination of coal feed crushing, washing and removal of 0–0.1 mm superfine particles. Flotation of the size fraction - 0.1 mm could produce a clean coal float with the ash less than 40%, provided that slimes should be removed before flotation. From results of the study, it was found that the most suitable flowsheet for washing of Nui Hong high ash coals should include crushing of the feed down to -6 (8) mm, washing by rotary scrubber screens to separate clean coal of 0.1–6 (8) mm, desliming of -0.1 mm fraction by spiral classifier before flotation. From the study samples with the average initial ash content of 55%, a common clean coal product with ash content of about 40–45% and with a yield of over 60% were obtained according to the proposed flowsheet. The quality of the clean coal matched with Vietnam coal quality standard as 6B grade fine coal (TCVN) so that it could be supplied to the local thermal power plants.

Simulation of layout rearrangement in the grinding/classification process for increasing throughput of industrial gold ore plant

In this study, a simulation of layout rearrangement in grinding/classification process was conducted to increase the throughput of an industrial plant processing 5.9 t/h of gold ore in Jeollanamdo province, Korea. The layout was rearranged to maintain the final product particle size while restoring the loss of throughput that has resulted from recent developments in mines. The process is composed of two-stage circuit, the first stage is an open circuit of the first ball mill and spiral classifier, and the second stage is a closed circuit of the second ball mill and hydrocyclone. Particle size distributions of each streams were predicted through simulation, using the population balance (PBM), Stokes’ and Plitt’s models for the ball mill, spiral classifier, and hydrocyclone, respectively. Lab-scale parameters for PBM were obtained by conducting batch grinding tests. The obtained lab-scale parameters were scaled-up using an empirical scale-up equation based on the industrial plant conditions. Using the obtained particle size distributions, the reduction ratio based on the 80% passing size was calculated to be 80.5 for the first ball mill, while it was only 1.19 for the second ball mill. To solve the process imbalance problem, a layout rearrangement that involves the switching of the first and second ball mills in the process was proposed. The final product was finer, with the 50% passing size reducing from 35 μm to 31 μm. The throughput of the industrial plant can therefore be increased by approximately 36% to 8 t/h. This study provides the guideline of the methodology which can help in adapting the simulation of layout rearrangement in the grinding/classification process for an industrial plant.

Optimisation of Operational Parameters of a Spiral Classifier Using Design of Experiment (DOE)

Abstract
 Classifying Mn Ore to improve upon the grade and the properties has become a crucial activity for the Mn industry since it increases the market value of the ore. Ghana Manganese Company (GMC) has renovated their oxide washing plant by integrating it with a spiral classifier to make a batch system operating process. Particle size of <3.35mm (Mn grade of 43-47%) obtained from the primary section of the plant served as feed to the classifier and with the plant condition (i.e. at 60 min washing time, 30 rev/min speed of spirals and feed tonnage of 6 t), Mn grade of 49% was achieved. This paper focused on the optimisation of some selected operational parameters of the classifier to obtain a Mn grade >50% using Design of Experiment (DOE). Series of test works were designed using the DOE for the classifier using the constraints of washing time (30-90 min), speed of spirals (20-40 rev/min) and feed tonnage (6-9 t). The outcome of the test work after simulation showed that all the selected parameters had a great influence on Mn grade. The spiral speed and feed tonnage correlated negatively to the Mn grade with washing time correlating positively. Operating the spiral classifier at a feed rate, spiral speed and washing time of 6 t, 25 rev/min, and 30 min, respectively, yielded Mn grade of 53%. A Confirmatory test using the established conditions gave a Mn grade of 53%, which is a 4% increment in the previous Mn grade which was 47%. The outcome of the studies is the new established operational conditions which is adhered to by the plant, producing a manganese concentrate grade ranging between 52-54%.
 
 Keywords: Design of Experiment (DOE), Spiral Classifier, Grade, Manganese

Production of process automation technology in the first stage of preparation ore of wet grinding

The creation of a new technology of automation of ore preparation processes in cycles of wet ore grinding is considered on the basis of analysis and modeling, modeling of the technological and physical features of apparatus and processes. An example of creation automation technology for controlling the performance of a spiral classifier in sand, modeling, testing technology and practical use in the conditions of the ore processing plant.

Failures and a concept of corrosion protection system for spiral classifiers at KGHM Polska Miedź S.A. Ore Concentration Plant

The Ore Concentration Plant, where the process of flotation is carried out as well as the final production of copper concentrate, plays a key role in the entire production line of KGHM Polska Miedź S.A. Majority of operations related to the run-of-mine preparation to copper flotation enrichment are carried out in a water environment. The maintaining of production process continuity requires to pursue minimisation of many production limitations. The corrosive action of the technological medium, being a salted water suspension of ground copper ore, is one of them. The concept of spiral classifiers cathodic protection presented in this paper may become an alternative to the anti-corrosion protection methods of machinery and equipment used now at the KGHM.The obtained results of research indicate a possibility of significant reduction of classifiers corrosion rate at the application of cathodic protection and of a few times extension of the period of spiral classifiers operation, which replacement generates substantial operating costs.

Enhanced gravity particle classifier: Experiments with 3D printed device and computational fluid dynamics simulations

AbstractCentrifugal force developed in a fluid flow through closed spiral channel produces enhanced gravity environment to facilitate particle classification. The novel design is inspired by open channel spiral concentrators that are used in mineral processing industries. The concept is initially validated through computational fluid dynamics (CFD) simulations. Preferential movement of coarser particles, which experience greater centrifugal force, to the outer periphery was observed. These predictions are validated by conducting experiments on a 3D printed spiral classifier. The CFD simulations compared well with observed experimental separation function. The model was further used to conduct parametric study of various design and operational parameters. Simulations reveal that the cut‐size could change from 8 μm to 260 μm depending on the splitter position. The novel device will allow a direct and online control of cut size/density when suitably enhanced with required mechanisms.

Experimental Investigation of Novel Enhanced Gravity Closed Spiral Classifier

Classifiers have found wide applications in the mineral processing industry. In this study, a novel enhanced gravity closed spiral classifier is presented. This device uses induced centrifugal force to classify particles. A functional prototype of the separator was 3D printed to experimentally validate the concept. The performance characteristics of the classifier were established by conducting experiments under different process and design conditions. Silica slurries with particle loading of 5–15 wt% were used in this work as a model system. The particle size distribution analysis was performed using laser scattering particle size distribution analyser (LSPSDA). The effects of particle loading, velocity of feed stream, and number of turns of spiral were explored. The equipment could be used in many applications ranging from size (mass) classification to disposing of unwanted gangue.

Analytical presentation of the separation of dense suspension for the extraction of amber

New devices were developed to increase the extraction of amber, especially with the size less than 5 mm, which can not be extracted at the present time. They are made on the basis of a hydraulic spiral classifier using vibration and bubbling with air bubbles. Analytical formulas are needed to calculate such devices, in first, for free motion of particles, then the constrained motion, and then to determine the effect of vibration and bubbling on the speed. This article discussed the first part of the problem – hydrodynamics of free movement of amber and quartz particles in a mixture of amber sand-clay rocks with water. The technique and formulas of calculation of kinematic viscosity and speed of movement are given. The dependences of the kinematic viscosity and the speed of free deposition of quartz and free ascent of amber on the density of the suspension for particles size less than 5 mm are obtained. The non-linear character of the dependence of the speed of ascent of amber from the density of the suspension is set. The results obtained are the basis for the calculation constructional parameters and technological characteristics of the hydraulic classifiers of new construction.

Increasing efficiency of technological process by limiting impact of corrosive environment on operation of spiral classifiers

Most of the technological operations related to the preparation of the output to be enriched and to the production of the final copper concentrate take place with the use of water environment. Water management, besides using innovative technical and technological solutions, is a significant factor in the whole copper ore enrichment process. Mine water resources and surface water of the tailing pond named “Żelazny Most” are the two sources of technological water. Its physico-chemical composition is not insignificant for both the flotation process and the machinery and equipment maintenance. The concept of electrochemical protection of the spiral classifier presented in this article is the supplement and alternative for anti-corrosion protection of the machinery and equipment used in KGHM Polska Miedź S.A. Ore Enrichment Plant. The adequate appreciation of the spiral classifier characterisation and the working conditions will allow for the optimal adjustment of cathodic protection installations with the anode polarization system. Research into the development of an effective protection method will combine two complementary types of anti-corrosion protection systems, that is the passive (a protective coating) and the active (a cathodic protection). The effect of the planned research will be the evaluation of the potential possibilities of the corrosive and erosive impact limitation of the spiral classifier working condition. And, moreover, it will lead to an extension of working hours and the reduction in the costs of the technological circuit.

Research of the technical characteristics of the electromechanical drive system of spiral classifier

Research of the technical characteristics of the electromechanical drive system of spiral classifier