Heavy Medium Cyclone Research Articles

Overview of coal sludge gravity concentration technologies

The purpose of the study is to collect data and analyze modern development trends of gravity concentration technologies and equipment for coal sludge enrichment. Conducted generalization and analysis of scientific and technical information allowed to state that some attempts have been made recently to enrich coal slimes using mainly gravity concentration methods. Each of these methods involves a number of processes based on general physical and physicochemical properties serving the criteria for material separation as well as on the differently applied additional separating forces and machinery and apparatus designs. The latter include heavy-media cyclones, spiral separators, hydrosizers, concentration tables and wash boxes. The author considers the operation principle of the listed gravity equipment, demonstrates the advantages and disadvantages of each of the apparatuses. The data given indicate that, modern gravity equipment used for coal sludge enrichment features satisfactory indicators of the average probable deviation. To identify the rational topology of concentration diagrams for a particular object, the most optimal type of gravity concentration equipment or its combination is selected depending on the characteristics of the material composition. The analysis of data has shown that the most promising, highly efficient, effective, environmentally friendly and resource-saving gravity concentration method is spiral separation.

Product specification and economic benefit maximization prediction model of a coal preparation plant in Datong, Shanxi

ABSTRACT Due to the adjustment of the Chinese industrial structure in recent years, the coal industries are facing a sluggish market environment. Therefore, it is important to study the product specification prediction and economic benefit maximization prediction of coal preparation plants. First, the washability data and distribution curve models were used to calculate the quantity and quality index of the products of the shallow slot heavy medium separator, the heavy medium cyclone, and the spiral separator, respectively. A gravity separation prediction model was built and the average fitting error of the model was 2.89%. Second, the calorific value – (ash and sulfur) model was built, in which SPSS was used to eliminate abnormal points. A mathematical model of the price of clean coal – calorific value was built. Finally, a genetic algorithm was used to optimize each sorting process to find the best sorting density of each sorting system: the result of the shallow slot heavy medium separator was 1.72 g/cm3, that of the heavy medium cyclone was 1.99 g/cm3, and the result of the spiral separator was 1.86 g/cm3. The maximum sales revenue of raw coal per ton from the economic benefit maximization prediction model was 379.79 yuan. The models provided forward-looking guidance for the related adjustments of production.

Destoning the Moatize Coal Seam, Mozambique, by Dry Jigging

This paper proposes pre-beneficiation studies by air jigs of the coal layers from a Moatize coal deposit. Pre-beneficiation, also called destoning, removes tailings before the beneficiation plant. The air jigs operate in the same granulometric size range as the heavy-media cyclones (HMCs) that are installed in the preparation plant. With the destoning, the heavy-media circuit operates with a lower coal feed and higher organic matter contents, increasing its cutting efficiency and lowering operational costs. The use of air jigs reduces the total water consumption in the plant, which is especially important for the region where the plant is installed, as water is particularly scarce. Four coal layers of the Moatize coal deposit were studied, which are currently exploited in the mine. As main results of the study, it is possible to say that the concentration of lights (feed of the preparation plant) and heavies (waste fraction) in air jigs can be carried out with reasonable efficiencies for all coal layers studied, making air jigs a feasible option for coal destoning.

The beneficiation of tailing of coal preparation plant by heavy-medium cyclone

Dense-medium cyclones have been used for beneficiation of fine particles of coal. In this study, the usability of cyclones in the beneficiation of tailings of a coal preparation plant was investigated. For this purpose, separation tests were conducted using spiral concentrator and heavy medium cyclones with the specific weight of medium 1.3–1.8 (g/cm3) on different grading fractions of tailing in an industrial scale (the weight of tail sample was five tons). Spiral concentrator was utilized to beneficiate particles smaller than 1 mm. In order to evaluate the efficiency of cyclones, sink and float experiments using a specific weight of 1.3, 1.5, 1.7 and 1.9 g/cm3, were conducted on a pilot scale. Based on the obtained results, the recovery of floated materials in cyclones with the specific weight of 1.40, 1.47 and 1.55 g/cm3 are 17.75%, 33.80%, and 50%, respectively. Also, the cut point (ρ50), which is the relative density at which particles report equally to the both products are 1.40, 1.67 and 1.86 g/cm3. The probable errors of separation for defined specific weights for cyclones are 0.080, 0.085 and 0.030, respectively. Also, the coefficients of variation was calculated to be 0.20, 0.12 and 0.03. Finally, it could be said that the performance of a cyclone with a heavy medium of 1.40 g/cm3 specific weight is desirable compared with other specific weights.

Evaluation of ground calcite/water heavy media cyclone suspensions for production of residual plastic concentrates

Viable recycled residual plastic (RP) product(s) must be of sufficient quality to be reusable as a plastic or source of hydrocarbons or fuel. The varied composition and large volumes of such wastes usually requires a low cost, high through-put recycling method(s) to eliminate contaminants. Cyclone separation of plastics by density is proposed as a potential method of achieving separations of specific types of plastics.Three ground calcite separation medias of different grain size distributions were tested in a cylindrical cyclone to evaluate density separations at 1.09, 1.18 and 1.27 g/cm3. The differences in separation recoveries obtained with these medias by density offsets produced due to displacement of separation media solid particles within the cyclone caused by centrifugal settling is evaluated. The separation density at which 50% of the material of that density is recovered was found to increase from 0.010 to 0.026 g/cm3 as the separation media density increased from 1.09 to 1.27 g/cm3. All separation medias were found to have significantly low Ep95values of 0.012–0.033 g/cm3. It is also demonstrated that the presence of an excess content of <10 µm calcite media particles (>75%) resulted in reduced separation efficiencies. It is shown that the optimum separations were achieved when the media density offset was 0.03–0.04 g/cm3.It is shown that effective heavy media cyclone separations of RP denser than 1.0 g/cm3 can produce three sets of mixed plastics containing: PS and ABS/SAN at densities of >1.0–1.09 g/cm3; PC, PMMA at a density of 1.09–1.18 g/cm3; and PVC and PET at a density of >1.27 g/cm3.

Biodesulfurization of a Coarse-Grained High Sulfur Coal in a Full-Scale Packed-Bed Bioreactor

Biodesulfurization of a high-sulfur and medium-ash coal product was carried out in a 5-m tall packed bed bioreactor using a mixed culture of iron- and sulfur- oxidizing microorganisms. The feed coal (4 tones) was obtained from a heavy media cyclone product from Takht-Zeitoon coal mine (Tabas, Iran) with a density of -1.4 g/cm3 and a grain size of 0.5-25 mm, having the ash and sulfur contents of 14.92% and 2.46%, respectively. The pilot scale process was performed in a semi-continuous mode with a solution injection rate of 2.5-4.5 lit/min/m2, aeration rate of 4-12 m3/h/m2 and solution pH of 1.7-2, over a period of 190 days. Iron and sulfate ions were controlled during the process in two 1500-L stirred tank reactors by goethite and gypsum precipitation processes, respectively. The column biodesphurization in a period of 170 days was followed by a washing step with HCl to remove sulfate precipitates. Results showed that the total sulfur and ash contents reached to 1.69% and 11.04%, respectively, which were corresponded to 31% sulfur removal and 26% ash removal. It was indicated that biodesulfurization has a good industrial potential to treat coarse-grained high sulfur coals.

Effect of some operating variables on the performance of a 150 mm Heavy Medium Cyclone treating high ash Indian Coking Coal

Tests were carried out on a 150 mm heavy medium cyclone test rig treating coal in the size range - 13 +0.5 mm. A total of twenty seven experiments were carried out by varying the parameters like vortex finder diameter, spigot diameter and inlet feed pressure. The effect of these variables on the performance of the 150 mm Heavy Medium Cyclone was investigated. The results indicate that it is possible to achieve about 30.1% clean coal at an ash content of 18.5% at a feed pressure of 10 lb/in2, vortex diameter of 63.75 mm and spigot diameter of 31.5 mm. The tromp curves obtained from operating the cyclone gave a probable error of 0.04, indicating good separation efficiency.

Effect of some operating variables on the performance of a 150 mm Heavy Medium Cyclone treating high ash Indian Coking Coal

Tests were carried out on a 150 mm heavy medium cyclone test rig treating coal in the size range - 13 +0.5 mm. A total of twenty seven experiments were carried out by varying the parameters like vortex finder diameter, spigot diameter and inlet feed pressure. The effect of these variables on the performance of the 150 mm Heavy Medium Cyclone was investigated. The results indicate that it is possible to achieve about 30.1% clean coal at an ash content of 18.5% at a feed pressure of 10 lb/in2, vortex diameter of 63.75 mm and spigot diameter of 31.5 mm. The tromp curves obtained from operating the cyclone gave a probable error of 0.04, indicating good separation efficiency.

Numerical Computation and Analysis of Particle Trace Based on Aerodynamic in Heavy Medium Cyclone

The theory, model and algorithm of three products heavy medium cyclone flow field were researched, and the heavy medium cyclone flow field was simulated based on aerodynamic. Through the researches, the numerical discrete algorithm of heavy medium cyclone flow field was deduced, the calculation algorithms of heavy medium cyclone flow field were given, the washed coal particle trace, intermediate coal particle trace, gangue particle trace in three products heavy medium cyclone, and the separation rules based on aerodynamic and flow field characteristics of three products heavy medium cyclone were obtained.

Numerical Computation and Analysis of Heavy Medium Cyclone Turbulence Flow Field

The theory, model and algorithm of three products heavy medium cyclone flow field were researched, and the heavy medium cyclone flow field was simulated. Through the researches, the numerical discrete algorithm of heavy medium cyclone flow field was deduced, the calculation algorithms of heavy medium cyclone flow field were given, the flow trace in three products heavy medium cyclone, and the separation rules and flow field characteristics of three products heavy medium cyclone were obtained.

An optimization study of yield for a coal washing plant from Zonguldak region

In this study, a coal washing plant in Zonguldak was optimized using equalization of incremental product quality approach which maximizes plant yield for a given ash constraint based on float–sink data. By maximization of yield using Solver which is an optimization routine available in Excel® for the identical elementary ash content and the specified ash level of 9.50%, the optimum cut points were determined for washing of coarser size fraction (100-18mm) and finer size fraction (18-0.5mm) by Drewboy Heavy Medium (HM) Bath and HM Cyclone, respectively. The results were compared with the plant operations in terms of product yield and ash content. Calculated yield % and ash % values with experimental yield % and ash % values from float–sink data of the used coal were also compared and they were in good agreement (R2>0.99). By equalization of the incremental ash in order to get composite ash of 9.5%, the composite yield was maximized to 30.71% while the plant's yield was about 24.00%. This approach identified the optimum operating conditions for individual cleaning circuits as 1.693 and 1.682 for Drewboy HM Bath and HM Cyclone, respectively. It is worth pointing out that, this increase (6.71%) in the yield would be remarkable when considering the whole life of the washery and the annual production of the plant (about 700000tons). In addition, the yield was maximized to 33.41% for the target ash of 11.61% by similar optimization studies. The optimum operating cut points for HM Drewboy Bath and HM Cyclone was determined as 1.900 and 1.888, respectively. Yield optimization was also performed by taking α equals to 80, which can be assumed ideal for HM separators. The results obtained by the two different calculations were very close to each other.

Process Control for a Coal Washing Plant Using a Range Control Chart and Multidimensional Scaling Analysis

In this study, a coal washing plant dataset was evaluated by using the range control chart and multidimensional scaling analyses. These analyses were conducted on the density values of a heavy medium vessel circuit and a heavy medium cyclone circuit. The range control charts indicated that the variations in the density values for the heavy medium vessel circuit and the heavy medium cyclone circuit were significantly high. The density values for the heavy medium vessel circuit and the heavy medium cyclone circuit were examined by multidimensional scaling analysis. The results of multidimensional scaling analysis findings supported the results obtained from the range control charts. Finally, this study showed that the usefulness of statistical process control techniques, such as range control charts and multidimensional scaling analysis, in helping decision makers in coal washing plant management.

Density distribution in a heavy-medium cyclone

Heavy-medium cyclones are widely used to upgrade run-of-mine coal. But the understanding of flow in a cyclone containing a dense medium is still incomplete. By introducing turbulent diffusion into calculations of centrifugal settling a theoretical distribution function giving the density field can be deduced. Qualitative analysis of the density field in every part of a cylindrical cyclone suggests an optimum design that has exhibited good separation effectiveness and anti-wear performance when in commercial operation.

Determination of design parameter for three-product heavy-medium cyclone

Analyzed the selected raw coal nature and forecasted the number quality of its separated product. Considering each product’s density, volume, and suspending liquid assignment, combining the separating mechanism of the cyclone and the relative formulas obtained from scientific experimentation and practice, the structure parameter was determined by calculation. This provides a more scientific reasonable method for determining the structure parameter of the unpressurized feeding three-product heavy-medium cyclone.

The Research of Large-Diameter &amp; Energy-Saving More Medium Supplied Gravity-Fed Three-Product Heavy Medium Cyclone

The characteristics and the development restrict factors in large-diameter area of the traditional three-product heavy medium cyclone are described. The paper mainly describes the structure and principles of large-diameter &amp; energy-saving more medium supplied gravity-fed three-product heavy medium cyclone. The simulation analysis of this cyclone (DWP type) is presented. The results show that this type of more medium supplied cyclone is better than the one medium supplied cyclone for it has a faster separation speed, high processing ability and better separation efficiency. The applications in field of the 3SNWX1500/1100-Ⅳ type cyclone which using the new technology indicated that there have energy-saving, a high output, a stable separation efficiency, a high precision and a significant economic benefits.

Research on super-low-ash anthracite preparation

The fundamental question of super-low-ash coal preparation is how to furthest depress high ash component pollution. A jigging process was used to remove high ash refuse and middling, then a high precision heavy medium cyclone was used to further separate near gravity light material. A two-stage heavy medium cylindrical cyclone with the same separation density was used to increase the precision of separation. The feed was de-slimed and fine-grind coal was added with media to improve the stability of the suspension. The pump frequency conversion timing and an air spring were used to steady the cyclone inlet pressure. Based on a series of study and pilot tests, a 1.00 Mt/a (output) commercial separation system with Ep value under 0.015 was built up. Super low ash (Ad 2.00%) Taixi Anthracite has been put into commercial production.

Fine coal circuitry considerations in treatment of soft coal with difficult washabilities

A typical process used in Chinese metallurgical coal preparation plants employs heavy-media separation to treat the coal coarser than 0.5 mm. The − 0.5 mm fine coal is treated with froth flotation. A major disadvantage of this process is that a large quantity of fine coal is recycled in the heavy-media cyclone circuit, which results in high magnetite losses. The − 0.5 mm fine coal in the media is a result of poor raw coal deslime screen efficiency and the continuous breakage associated with the processing of soft coal. Another disadvantage of this typical process is that some coarse clean coal particles are lost to the froth flotation tailings. This investigation focuses on the simulation of processing fine soft coal with water-only cyclone (WOC) and spirals. WOCs and spirals have become popular devices for treating fine coal. WOCs can operate at low specific gravity cut points to produce low ash clean coal while spirals tends to operate at high specific gravity cut points and act as a scavenger to rewash the underflow (refuse) from WOCs. The combination of WOCs and spirals can compete with a heavy-media cyclone with respect to both efficiency and clean coal yield when treating 1 mm × 100 Mesh fine coal. This fine coal processing circuit can subsequently increase the bottom size of the heavy-media cyclone feed from 0.5 mm to 1 mm which will reduce the loading of the heavy-media cyclone circuit. This change in circuitry thus reduces magnetite consumption without scarifying separation efficiency of the 1 mm × 0 size fraction. Furthermore, the reduction of the nominal top size of the froth flotation feed from 0.5 mm to 0.15 mm will greatly decrease or eliminate the loss of clean coal to flotation tailings.

Comparative Study on Magnetite Medium Stability in a Vorsyl Separator and in a Heavy Medium Cyclone

It is reported in the literature that a Vorsyl separator (VS) performs better than a heavy medium cyclone (HMC) when treating coals with high near-gravity material. The discussions are generally based on the results of laboratory or plant-scale data treating various coals. However, no effort has been made so far to identify the reasons behind the superior performance of a VS compared to a HMC. Medium stability is an important parameter, which affects the performance of any heavy medium separator. Therefore, an attempt has been made to study the magnetite medium stability behavior inside a HMC and VS at identical operating conditions. It is found that at any fixed-operating condition, the differential between the underflow and overflow slurry density is always less in a VS than in a HMC. Possible theoretical explanations supported by experimental data have been provided to substantiate this finding.

Integrating flotation to improve the performance of an HMC circuit treating a low-rank fine coal

One reason that heavy media cyclone (HMC) circuits suffer from the inadvertent loss of magnetite and fine coal is the presence of nonmagnetic material in the magnetic separator feed. In this study, flotation was applied to the undersize fractions of the HMC drain-and-rinse screens to minimize these problems. These fractions, which contain 17.9% nonmagnetic material, are currently sent to magnetic separators and the nonmagnetic portion from the separators contains 39.1% ash. Applying flotation resulted in a clean coal product with an ash content of 8.7% and a calorific value of 6,300 kcal/kg. The refuse from flotation, which will be sent to the magnetic separators, contains 7.7% nonmagnetics.

Simulation of heavy medium cyclone performance

Heavy medium cyclones (HMCs) are commonly used to clean run-of-mine coal in the 50- to 0.5-mm size range. Unfortunately, field studies suggest that industrial HMC circuits are often poorly designed or improperly operated, resulting in significant losses of recoverable clean coal. To assist plant engineers in overcoming these problems, a spreadsheet-based simulation package has been developed to predict HMC performance based on mathematical expressions originally developed by Wood (1990). A case study is provided to illustrate the predictive capabilities of this simulation package for an industrial HMC.