Slime Particles Research Articles

Effect of APMImBr ionic liquid on the migration of silver in copper electrorefining

As the grade of copper concentrate decreases and its composition becomes increasingly complex, the silver content in the anode plate casting after fire refining increases. This leads to a high silver content in the copper cathode during electrorefining and a substantial loss of precious metals. This study investigated the effect of 1-aminopropyl-3-methylimidazolium bromide (APMImBr) ionic liquid on the migration of silver during high-silver anode plate electrorefining. The results show that APMImBr is adsorbed on the anode surface by reacting with Ag+ released from the anode to form AgBr precipitates, thereby preventing Ag+ ions from entering the electrolyte. Simultaneously, agglomerates of fine Ag–Se compounds and AgBr particles form, resulting in anode slime particles that are sufficiently large to settle quickly to the bottom of the cell, thus inhibiting fine silver-containing particles from adhering to the cathode. Furthermore, APMImBr adsorbs onto the cathode surface, forming CuBr intermediates and inhibiting Cu2+ electrodeposition. This facilitates the refinement of the surface grains and flattens the copper cathode surface. The Ag content of the cathode decreased continuously as the concentration of APMImBr increased. The Ag content of the cathode decreased by 41.67% from 6.0 ppm (no additives) to 3.5 ppm upon the addition of the optimal concentration of 300 mg/L of APMImBr.

Impact of 5-Amino-1H Tetrazole on Reducing Silver in Copper Cathodes during Electrorefining with High Silver Content Anode Plates

As the grade of the copper concentrate decreases and its composition becomes increasingly complex, the silver content in anode plates cast after fire refining increases, leading to a higher silver content in the copper cathode during electrorefining and a substantial loss of precious metals. This study investigates the impact of 5-amino-1H tetrazole (5-AT) on reducing silver in copper cathodes during electrorefining with high silver content anode plates. 5-AT forms an “adsorption layer” on the anode surface, reacting with Ag+ released by the anode to form a precipitate and prevent Ag+ from entering the electrolyte. This process agglomerates fine Ag-Se compounds and AgCl particles, creating larger anode slime particles that settle quickly, thus inhibiting fine silver-containing particles from adhering to the cathode. Furthermore, 5-AT adsorbs on the cathode, binding with Cu+ and promoting the Cu2+ electrodeposition process while inhibiting Ag+ electrodeposition. This facilitates uniform copper cathode grain growth and reduces inclusions in the copper cathode. The grain size of the copper cathode initially decreases and then increases as the concentration of 5-AT increases. At an optimal 5-AT concentration of 15 mg/L, the Ag content in the copper cathode decreased from 6.9 ppm to 4.7 ppm, indicating the potential efficacy of 5-AT in improving the quality of electrorefined copper.

Evaluation of calcined coal slime in binary and ternary ordinary portland cement composites: The role of calcination temperature

Coal slime is a by-product of coal washing plants, which accounts for around 8.3% of total coal production. China generates about 200 million tons of coal slime annually, and most of which can not be utilized efficiently. As a result, the disposal of coal slime leads to serious environmental problems and high costs. To provide a green utilization of coal slime, this study investigated the preparation of binary and ternary cement binder systems by using various calcined coal slime particles. The effects of calcination temperatures (600 °C, 700 °C, 800 °C, and 900 °C) on the evolution of mineral phases, microstructure and morphology of coal slime were addressed and discussed. The feasibility of calcined coal slime in blended cement preparation was tested and evaluated in comparison with calcined coal gangue. The results indicated that kaolinite in coal slime can be effectively transformed into metakaolin at 600 °C. The increase of calcination temperature after 600 °C reduced the reactivity, porosity and water demand of calcined coal slime. 600 °C Calcined coal slime effectively promoted the formation of monosulfate and the monocarboaluminate in binary and ternary cement, respectively, as well as the hydration process. The highest compressive strength of the calcined coal slime blended sample achieved 48.04 MPa, which presented a higher performance than the calcined coal gangue. The organic components in coal slime could be the key to reaching a high reactivity at a low (600 °C) calcination temperature. The calcined coal slime has the potential to be a reactive additive in cement-based materials.

Ultrasonic-assisted flocculation and sedimentation of coal slime water using the Taguchi method

ABSTRACT As the intensity of mining increases, the gangue content in coal slime water increases, leading to difficulties in settling suspended particles. In recent years, ultrasound technology has received much attention in the field of water treatment due to its high efficiency and convenience, and coal slime water undergoes ultrasonic pretreatment to improve flocculation. This study explored the effects of four factors, namely ultrasonic power, ultrasonic time, flocculant dosage, and coal slime water concentration, on the flocculation efficiency of coal slime water using an orthogonal design. The optimum conditions for ultrasound-assisted coal slime water flocculation were found to be an ultrasonic power value of 192 W, an ultrasonic time of 8 min, pH 8, a flocculant dosage of 24 mg/L, and a coal slime water concentration of 30 g/L. The flocculation efficiency reached 92.64%. After a certain time of ultrasonic pretreatment (8 min), there was a reduction in the amount of clay on the surface of the coal slime particles, the potential decreased to −3.07 mV, and the average and fractal sizes of the flocs were 80.45 µm and 2.01, respectively. A range of methods was used to confirm that the settling effect of the coal slime water had been improved by ultrasonic pretreatment.

Insight into filter cake characteristics of fine coal tailings assisted by CPAM and α-HH during pressure filtration

To improve the filter cake structure and efficiently dewater coal slime, CPAM and α-HH were designed for combined use in filtration experiments. The conditioned coal slime dewatering effect was measured using a newly designed pressurized dewatering device; the auxiliary mechanisms were analyzed from various perspectives, including hydrophobicity, electrostatic repulsion, coal slime composition and filter cake structure. A CCD experiment indicated that the optimal concentrations of the two additives in combination were 205.90 g/t CPAM and 56.25 mg/g α-HH. Under these conditions, the coal slime water CST decreased to 31.6 s, the filtration rate increased to 177.01 mL/(s·m2), the filter cake moisture content decreased to 16.46%. CPAM still acted as a polymer flocculant, causing the coal slime particles to form large flocs, while the addition of α-HH reduced the absolute zeta potential of the filtrate to 1.36 mV, thus decreasing the static repulsive forces between coal slime particles, promoting floc formation and increasing the floc chord length to 83–185 μm. These effects enhanced the CPAM flocculation effect. In the CPAM system, these phenomena accelerated the hydration reaction of α-HH and produced many CaSO4·2H2O crystals. These crystals formed an interwoven skeleton in the coal slime flocs, increasing the CDI increased to 1650.04, and increasing the filter cake porosity from 13.26% to 16.45% and effectively improving the filter cake pore connectivity and permeability, which improved the filtration effect. This study could provide a new method and perspective for the efficient pressurized dewatering of coal slime.

From waste to wealth: Unlocking the value of copper anode slimes through systematic characterization and pretreatment

Technology, in addition to supply and demand, is driving current advances in mineral processing. Over the past three decades, demand for various minerals has continued to rise, while the mineral processing sector has faced challenges such as the need for more sophisticated ore treatment, lower plant feed quality, and poorer plant performance due to mixing of ores with varying characteristics. Gravity separation has long been a cost-effective method for the mining industry, especially in the processing of precious metals. Copper anode slime contains significant amounts of gold, silver, and platinum group metals. In this study, we tested the functionality of a slime shaking table for recovering precious metal components by recycling barite particles from the copper anode slime. Additionally, we used several characterization methods, including backscattered electron microscopy, energy-dispersive X-ray spectroscopy, optical microscopy, and physical testing, to improve our understanding of the copper anode slime particle phases. This study highlights the challenges associated with recycling and processing secondary materials and demonstrates the complexity of physical separation methods for extracting barite particles from copper anode slime.

Experimental investigation of circulating fluidized bed combustion of dry powders of coal slime

Effective combustion of coal slime in circulating fluidized bed (CFB) boilers is essential for the sustainable development of clean coal technology. To overcome issues related to burning wet coal slime in CFBs, we propose to dry coal slime in a low-temperature drying system and burn the dried fine powders in a CFB with a highly efficient separator. This study reports a series of experiments conducted in a 4MWth pilot-scale CFB combustion test facility to assess the feasibility. The results demonstrate that the dried slime particles, which have a particle size distribution similar to that of circulating ash particles, can be burned stably, efficiently, and cleanly. The combustion of fuels with size distributions similar to that of circulating ash particles increases solids circulation rates, betters solids concentration distribution, enhances heat transfer combustion and improves operation and SO2 and NOx controls. Therefore, the study presents a potential opportunity to advance CFB combustion technology.

Influence of soda-sulfate mixture on physicochemical properties of saponite suspension

This article deals with the problem of clayey sludge utilization of diamondiferous ore enrichment. Thickening of saponite sludge by means of chemical treatment is currently considered as the most effective way to clarify the volume of water sufficient to maintain the recycling water supply of the enterprise and, as a consequence, to reduce the volume of additional water introduced into the process. The authors propose a new coagulant for settling saponite sludge - sodium sulfate mixture, which is a by-product of aluminum production. The use of sodosulfate mixture will reduce the amount of waste for both the diamond mining plant's concentrator and the alumina production. The question of the mechanism of interaction of saponite sludge particles with the proposed reagent is considered. The aim of the research is to find physical and chemical regularities of interaction of clayey slime particles with sodosulfate mixture. Chemical and mineral composition of used raw materials, surface charge of clay particles, granulometric composition of experimental samples and their electrokinetic potential were determined in the work. The results of the studies showed that the mineral composition of the clay slurry includes the following minerals: saponite, kaolin, serpentine, beidelite, dolomite. The surface charge of clay particles is negative. The chemical composition of the soda-sulfate mixture is represented in the form of oxides: Na2O, SO3, CO2, Al2O3. The dependence of the electrokinetic potential on the mass of the mineral additive introduced into the slurry was revealed. It was noted that the absolute value of ζ-potential remains above 30 mV despite increasing the concentration of the additive, but coagulation of clay particles occurs and the system in question loses sedimentation stability at a concentration of sodium sulfate mixture of 14.4 g/l.

Exploring the effect of sodium hexametaphosphate in coal slime flotation

In this paper, the influence of sodium hexametaphosphate (SHMP) in coal slime flotation was studied, and the interaction between SHMP and coal slime flotation particles was revealed through XRD test, contact angle measurement, zeta potential test, scanning electron microscopy analysis, XPS analysis, and DLVO theoretical calculation. The experimental results show that when the dosage of SHMP is 1500 g/t, the recovery rate of clean coal combustibles increases by 9.61 %. SHMP reduces the hydrophobicity of clay minerals (kaolinite) in coal slime flotation and also enhances the dispersibility of coal slime particle. Scanning electron microscopy and energy dispersive analysis showed that SHMP reduced the number of clay particles (kaolinite) on the coal surface, thereby reducing the ash content of the clean coal. In this paper, SHMP is mainly used to modify the surface of kaolinite so as to reduce the hydrophobicity of the mineral, that is, to improve the recovery rate of clean coal combustibles in coal slime flotation.

Full Characterization of Sarcheshmeh and Khatoon-Abad Copper Anode Slimes: Characterization Impact on the Decopperization Operation

Copper anode slime, a valuable by-product generated during the electrorefining process, is an important secondary resource for the recovery of metals, such as gold, silver, selenium, tellurium, PGMs and copper. A full characterization of the anode slime is an essential part of the efficient recovery of these valuable metals. In this research, the refinery slimes of the Sarcheshmeh and Khatoon-Abad copper complexes, were fully characterized and compared using inductively coupled plasma (ICP), X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and particle size analysis. Besides the bottom cell slime characterization, properties of the Sarcheshmeh’s adherent slime was also analyzed and correlated. Sarcheshmeh copper slime particle size was found much smaller than the Khatoon-Abad slime. For both slimes though, the major part the gold and tellurium are located in larger than 38-micron particles. The main difference in thermal analysis of the two slime samples was originated from their selenium content difference. This has caused the higher concentration of non-selenide copper compounds at Khatoon-Abad slime, resulted in its easier copper recovery. Decopperization of both bottom-cell slimes were investigated and a significant difference in copper dissolution behaviors of the two slimes were observed due to their characteristic difference including the copper-selenide phases and capsulated copper in the barium sulfate agglomerates. Copper dissolution from Khatoon-Abad slime was observed to reach 90% comparing to 40% for Sarcheshmeh slime using atmospheric leaching.

Scalable recycling of feldspar slime into high-quality concentrates by removal of colored minerals using the combined beneficiation processes

Feldspars are the main raw materials for glass and ceramics. The feldspar slime generated during beneficiation processes contains a high content of colored iron-bearing minerals, which is an obstacle to its utilization. In this study, dishwashing liquid is used as the flotation collector and frother, and combined beneficiation processes, including wet ball milling, froth flotation and magnetic and gravity separation, are employed to remove the iron-bearing minerals from feldspar slime in order to achieve high-quality concentrates. In the milling process, slime particles are pulverized to liberate fine impurity minerals, which are gradually separated and removed by the subsequent processes with the assistance of anionic surfactants in the collector. The mass recovery of feldspar concentrates decreases with increasing milling time and first decreases and then increases with increasing collector dosage. While the burnt whiteness of feldspar concentrates first increases and then decreases with increasing milling time and collector dosage, it continuously decreases with the prolongation of gravity sedimentation. When feldspar slime is milled for 2 h, floated with a 2% collector dosage and settled for 10 h in gravity separation, the resulting feldspar concentrate contains 12.6% Na2O + K2O and 0.21% Fe2O3, with a mass recovery and burnt whiteness of 58.0% and 53.6%, respectively. This feldspar concentrate meets the requirements of the glass and ceramics industries. The scalable and environmentally-friendly recovery of feldspar slime represents a promising route for the sustainable utilization of feldspar minerals.

Study on Dispersion and Mixing Mechanism of Coal Slime Particles in Jet Mixing Flow Field

The jet flow field is characterized by the dispersion and mixing of multiphase flow, which is widely used in the field of coal slime flotation. In this paper, the behavior of coal slime surface modification, the behavior of material suspension and the effect of different jet fluids on coal slurry blending were studied. Based on the action mechanism of the jet flow field, a jet device suitable for coal slime graded mixing was proposed, and the mixing effect of the jet device was tested. The results show that the jet flow field has strong effects on material dissociation and dispersion, and the mixing effect of a single jet is equivalent to that of the laser particle size analyzer’s own agitation device after stirring for 2.5 min at 500 r/min speed. The SEM test of material surface morphology and the changes of Al and Si elements measured by EDS show that the jet flow field can effectively remove the fine mud wrapped on the surface of coal particles. The precondition of material suspension is to have the just-suspended capacity. The critical jet velocity of coal slime suspension is in the range of 6 m/s~9 m/s. The mixing ability of the jet stream has certain limitations. The increase or decrease of the jet height will cause the decrease of the suspension percentage of sampling points in the tank. The gas jet mode can promote the reagent acting on the surface of the bubble liquid film to form oil bubbles, which is more suitable for hydrophobic mineral flotation. The optimal speed of the gas jet is 0.86 m/s, and the shortest cycle period is 1.0 T (T is one material cycle period). The flotation perfection index of 0.5–0.25 mm and less than 0.075 mm coal slime increased by 2.67% and 26.78%, respectively, indicating that the overall idea of the jet mixing device proposed based on the experimental conclusion is feasible.

Combustion and Fragmentation Characteristics of Single Wet Coal Slime Particle

ABSTRACT The combustion and fragmentation characteristics of wet coal slime particle are different from that of dried coal particle. In this paper, an understanding of the combustion process of wet coal slime particle through the combined results of the morphology characteristics, mass changes, and gas release pattern is provided. A tube furnace and high-speed camera were used to observe morphological changes of the combustion process of wet coal slime. For comparison, the mass change and gas release pattern of wet coal slime was monitored by a thermogravimetric analyzer and mass spectrometer (TG/MS). The four combustion stages of coal slime were observed for the first time: (1) drying and evaporation, (2) devolatilization and fragmentation, (3) volatile homogeneous combustion, and (4) char heterogeneous combustion. The water content in wet coal slime greatly affected the fragmentation of coal slime, it could build up a great internal pressure when evaporated, which caused the primary fragmentation to occur earlier and be more severe than traditional coals. The temperature and diameter of the slime were considered as factors for the occurrence of fragmentation and the level of it. A larger diameter with a higher furnace temperature resulted in a more severe fragmentation of the wet coal slime. The smaller coal slime at the lower temperatures did not experience the fragmentation stage. Here, the fragmentation and non-fragmentation zones of wet coal slime at different temperatures and different paticle diameters are given, which could be a guide for the combustion of coal slime in CFB(Circulating Fluidized Bed). Also, for larger diameters and lower setting temperatures, the ignition delay time and burnout time of wet coal slime became longer. The gas release pattern of wet coal slime during the combustion process was analyzed, and it was determined that it could be affected greatly by fragmentation. A model of the drying and evaporation stage of wet coal slime was established for the first time by using COMSOL Multiphysics. The results of the theoretical calculations show that there were two evaporation rate peaks of water when fragmentation occurred, which theoretically explained the early stage of the combustion process of wet coal slime, and the results were in agreement with the experiments.

Expansion/micro-explosion of ethanol-biodiesel droplet doped with microparticles in oxygenated hot co-flow

In this paper, under normal pressure and air atmosphere, the single droplet suspension method was used to study the expansion and evaporation characteristics of ethanol-biodiesel mixed droplets under different coal slime particle content and different particle size. In the experiment, a nickel wire was used as a suspension, a stepping motor was used for precise advancement, and the entire evaporation process of the droplet was completely recorded through color gradation processing and binary imaging technology. Experimental results show that the addition of micron-sized slime particles will increase the evaporation rate of droplets. The total evaporation rate (K) of the droplets increases as the content of slime particles increases, making the total evaporation time of the fuel droplets containing 3 % slime particles the shortest. The stable evaporation rate (K3) of the droplets first decreased and then increased, and the stable evaporation rate of the droplets containing 1 % of coal slime particles was the highest. Furthermore, at the same particle content, the evaporation rate of droplets containing 60 μm slime particles was the fastest.

The Synergistic Effects of Al3+ and Chitosan on the Solid-Liquid Separation of Coal Wastewater and Their Mechanism of Action.

It is important to identify an environmentally friendly and efficient flocculant that can replace polyacrylamide for the solid–liquid separation of coal wastewater. In this study, to explore whether chitosan can be used as an environmentally friendly and efficient flocculant for the solid–liquid separation of coal wastewater, AlCl3–chitosan was used to conduct flocculation–sedimentation and dewatering tests under different chitosan dosages and shear-strength conditions for the prepared coal wastewater. Focused beam reflectance was measured to dynamically monitor the number of refractory fine particles, and the settled flocs were photographed and analyzed with microscopy to explore the effect of AlCl3–chitosan on the flocculation settlement effect and floc characteristics. The synergistic mechanisms of AlCl3 and chitosan were investigated using quartz crystal dissipative microbalance and zeta potential measurement. The results showed that the addition of chitosan can significantly improve the flocculation–sedimentation and dewatering effects of coal wastewater. A reasonable dosage under a certain shear strength is conducive to the reduction of fine slime particles, which results in a compact floc structure, increases the floc size, and improves the settling effect. The synergistic effect of AlCl3–chitosan improved the electric neutralization and adsorption bridging abilities of the chitosan, and the mixed solution of AlCl3 and chitosan had stronger adsorption on the carbon surface. This study provides a new approach to the selection of flocculants for coal wastewater treatment.

Effect of surfactant and flocculant on low-rank coal slime filtration: From filter cake characteristics point of view

Filter aids are widely used in low-rank coal (LRC) slime filtration. However, their impact on filter cake characteristics is still unclear. In this paper, the effect of anionic polyacrylamide (APAM) and cetyltrimethylammonium bromide (CTAB) on the filter cake characteristics was investigated using Darcy’s filtration theory and low-field nuclear magnetic resonance (L-F NMR). The slime and filtrate property change was determined by contact angle, XPS, FBRM, Zeta potential and surface tension measurements. The results showed that the filter aid improved slime filtration rate and reduced filter cake moisture. The filter aid effect of APAM was better than that of CTAB. CTAB significantly improved the slime surface hydrophobicity with the contact angle increasing to 90.5°, and reduced the filtrate surface tension to 35.26 mN/m. However, APAM decreased the absolute value of slime Zeta potential by 7.48 mV, and increased the slime floc size by about 7–9 µm. Both CTAB and APAM can reduce the filtration resistance, but the effect of APAM was better than that of CTAB, because APAM greatly improved the filter cake permeability. L-F NMR results showed that CTAB increased the filter cake porosity only by 2.65%, while APAM significantly improved the filter cake porosity by 11.65%, especially the mesopore porosity of cake, which increased by 10.48%. It was indicated that CTAB reduced the filtration resistance by “lubricating” the pore wall of the filter cake, while APAM improved the filter cake porosity and permeability by weakening the electrostatic repulsion between slime particles and promoting floc formation through aggregation effect. This research provided a new perspective to reveal the mechanism of LRC slime filtration.

Effect of the Polymerized Titanium Ferric Sulfate (PTFS) Coagulant on Sedimentation of Coal Slime Water

High efficiency slime water settlement is very important for ensuring washing water recycling in coal preparation plants. In order to improve the sedimentation of coal slime water, an iron ion-based coagulant was prepared by titanium ion complexation action using titanium sulfate as a main raw material, Fe3+ and NaH2PO3 as a stabilizer and NaHCO3 as an alkalizing agent. The particle size distribution of coal slime was measured, and the sedimentation test for coal slime water was carried out with PAM, polyaluminum chloride and polymerized titanium ferric sulfate (PTFS), respectively. Then, coal slime water sedimentation was investigated at different PAM dosages and polyaluminum chloride or coal slime water of PTFS with various molar ratios of PAM and ferrotitanium. The results showed that PAM and polyaluminum chloride could not make coal slime settle down, and PTFS showed a poor settlement effect. When polyaluminum chloride and PTFS were used together with PAM, it produced a molecular weight of 3 million respectively. Polyaluminum chloride needs 6.66 × 10−10 mol of PAM, PTFS needs 0.66 × 10−10 mol of PAM and the effect of sedimentation is improved. When the molar ratio of PTFS was 1:7, polymerization performance was effective. The sedimentation effect of PTFS was better than that of polymeric aluminum chloride coagulant usually used in coal preparation plants, especially when combined with flocculant, and high efficiency was reached. The surface potential and surface free energy of coal slime particles before and after adding coagulant were measured and analyzed by XDLVO theory to explain the action mechanism of PTFS coagulant. Experimental results demonstrated that PTFS can significantly improve the sedimentation of coal slime water, save the dosage of PAM and increase economic benefit.

Statistical analysis of the distribution of impurities during copper electrorefining

Electrolytic copper refining makes it possible to obtain high purity metal, so the analysis of the main ways of impurity transition into electrolysis products is an actual problem. If it is solved, the process can be controlled when changing the composition of raw materials and, as a result, the content of impurities in the anodes. This paper uses the comprehensive analysis and synchronization of a large array of data on impurities concentrations in various process media (anodes, electrolyte, slime, and cathode metal) obtained on the series of commercial cells to identify the directions of impurity flows and relationship between their content in these media. It is shown that the transition of impurities from one process medium (source) to another (receiver) is implemented according to four main patterns: linear increase, no visible dependence, the presence of a limit concentration in the receiver and the presence of a threshold concentration in the source. The paper provides the results obtained in the statistical analysis of the distribution of six impurities (bismuth, arsenic, lead, sulfur, nickel and silver) belonging to different groups in four main pairs of the impurity source – receiver: anode – solution, anode – slime, slime – cathode, solution – cathode. The coefficients of linear regression equations are determined and their significance is estimated for all dependencies of the impurity concentration in the source on the content in the receiver. The coefficients obtained make it possible to explain the impurity transition paths observed in the commercial cells and predict the quality of cathode copper and the composition of slimes when the anode composition changes. The calculations showed that impurities are accumulated in cathodes due to the occlusion of slime particles and incomplete solution removal from the surface of commercial cathodes rather than due to electrochemical reactions. The copper electrorefining technology should be improved and developed so as to find surface-active additives that would prevent the adsorption of suspended slime particles on the cathode surface, as well as better wash them from the electrolyte.

Computer based Numerical Simulation and Experimental Study on Coarse Slime Separation in Water Medium Fluidized Bed

At present, there is still a lot of room to improve the separation effect of coal blocks, which is mainly due to the lack of effective support for the screening of coal blocks within a certain size and diameter range, which seriously affects and restricts the overall operation efficiency of coal preparation plant and the improvement of economic benefits of operation. Based on this, this paper first studies the current situation and problems of coarse slime separation process, then analyzes the numerical simulation technology and process of coarse coal slime particle number process in water medium fluidized bed, and finally gives the numerical simulation and experimental verification of coarse coal slime separation in water medium fluidized bed.

Effect of slime and dust emission on micro-cutting when processing carbon-carbon composites

Results of theoretical and experimental studies aimed at establishing features of micro-cutting with abrasive grains characterized by active emission of slime and dust particles were presented. The slime particles are just partially withdrawn from the interaction zone and partially change surfaces of the tool and the workpiece of a carbon composite material, in particular, of carbon-carbon and carbon-polymer groups. The above materials possessing a complex of unique physical and mechanical properties are used in high-tech production though composites remain difficult to process materials. The problems manifest themselves to their utmost in making various apertures, shoulders, cutting of holes, processing edges. The study has shown that the phenomenon of dust and slime emission in abrasive processing of carbon-based non-dense composites and plastics results from sliding fracture and cyclic weakening of the surface non-dense layer which exhibits quasi-brittle properties under the action of fast-moving micro-indenters. Conditionality of the average slime particle sizes by normal stresses in the cutting zone and the magnitude of protrusion of diamond grains above the cutting surface of the tool was revealed. Since it was found that the particles formed during cutting are only partially withdrawn outside the cutting zone and the degree of removal decreases with an increase in the processing time, a conclusion on the cause of change in the state of the tool surface was drawn. The remaining slime and dirt change topography of the surface which results in the cutting zone temperature rise to critical values. It was shown that the use of tools with cyclic advance makes it possible to partially improve the condition of material processing which is relevant for the implementation of the processes of ring diamond drilling, processing with diamond saw blades. It was proved that the intermittent application of areas of the diamond-bearing layer reduces the phenomenon of dirt particle sticking to the surface of the working tool. Thus, the tool stays free of dirt for longer and the machining process is more efficient