A case study of the modification potential of using spiral separators in the circuit of the Alborz-Sharghi coal processing plant (Iran (original) (raw)
Related papers
Designing a Spiral Splitter at the Zarand Coal Washing Plant
2014
Spiral separator is one of the equipment is used in mineral processing plants. This equipment commonly are used for separation of minerals (coal, iron, chromite, gold, zircon, etc.). Spiral separator performance (yield and product ash content) in addition to factors such as percent solids and flow rate of the feed, largely depends on how the materials exit from the spiral. In other words, at the end of the spiral trough, valuable, intermediate and waste materials should be considered completely separate. Poor design of spiral splitters caused mixing the valuable materials with middle and tailing. This ultimately reduce the quality of the final product as much as 40 to 60 percent (depending on the amount of mixing between the product and tailing). The new design of the splitters and avoiding mixing the valuable materials with middle and tailing increased the product quality, with a final value of about 55 % better than previously obtained.
A spiral separator is one of the commonly-used gravity-concentration devices. It has been widely used in the mineral processing of coal. Also, it is used for the inexpensive pre-concentration of low grade ores. Spiral separator consists of an open trough that twists downward in helical configuration about a central axis. The aim of the present study is the simulation of the flow of water in spiral separators. The study is based on volume of Fluid (VOF) approach and turbulence modeling. The results focus on waterflow characteristics such as the depth of water as well as the turbulence intensity. The results demonstrated that the water depth and turbulence intensity on spiral trough increase smoothly outward. Predicted results are compared with the experimental findings from LD9 coal spiral. Comparison between the predicted and the measured values show good agreement and the most accurate turbulence model is RSM.
This study presents a mathematical model to predict water-flow characteristics, especially primary (downstream) and secondary velocities on the spiral trough. The study is based on volume of Fluid (VOF) approach and turbulence modeling. The applied turbulence models are k-ε, RNG k-ε, SST k-ω, and RSM. The results show that the primary velocity increases on the spiral trough with increasing of the radial distance from central column, and the air friction with the water decreases the primary velocity at the free surface. The model is validated against experimental data from LD9 coal spiral. Comparisons between the predicted and the measured values show good agreements, and the RSM is the most accurate turbulence model while the SST k-ω model is the lowest accuracy.
Evaluation of the Performance of Tri-Flo Separators in Tabas (Parvadeh) Coal Washing Plant
Research Journal of Applied Sciences, Engineering and Technology, 2014
Parvadeh Coal Preparation Plant (CPP) was installed in 2008 for the production of the 750000 TPY of clean coal containing 10.5% ash from the raw feed having 44% ash and mainly coming from the long-wall mine. Three units of high capacity centrifugal separators (Tri-Flo) are used for the preparation of the coal in the size ranges of-50+6 mm and-6+0.5 mm. Tri-Flo separators are operating in double stages, so they can produce three products. The nominal feed capacities of the 700 mm Tri-Flo and each unit of 500 mm Tri-Floes are 120 and 70 TPH respectively. However, due to some of the operating difficulties in the coal mine, the current feed capacities to the separators are changed to 160 and 30 TPH accordingly. In this research, sink-float experiments on the representative samples of the Tri-Flo separators were used for the evaluation and optimization of their performance. The experiments were performed in six different densities. On the basis of the experimental results, the operating E p (Ecart Probable) value of the 700 mm Tri-Flowas 0.075 which was more than the design figure (0.035). Such a difference was mainly attributed to the changes in the feed characteristics. In the small Tri-Flo separator, E p values were measured as 0.062 and 0.087 for the size ranges of (-1+0.5 mm) and (-6+1 mm) respectively and were in good agreement with the design criteria. The optimization of the heavy media separation circuit of the plant is underway using the results presented here.
Effect of Operating Parameters on the Performance of Spiral Concentrator
Spiral concentrator, a critical device in the mineral sand beneficiation circuit, separates minerals based on their specific gravity differences. The effect of different operating parameters on the performance of Spiral has been studied through optimization experiments at different feed flow rates and splitter positions for four feed pulp densities ranging from 25-10%. The raw sand used in experimentation contains 12.5% slimes and 11% heavy mineral concentrate, out of which 80% was in the particle size range of -250 + 106 pm.
Mathematical modeling of separation behaviour of a spiral forwashing high ash coal
2006
Sustained Coal R&D activity has been crucial to the many successful clean coal technology developments that have been achieved globally. The aim has been to enhance the competitiveness of coal by providing technical and environmental improvements whilst at the same time reducing capital and operating costs. In coal preparation, simpler lower cost alternatives to froth flotation, such as the coal dense medium separator and spiral separators, have been adapted for cleaning of fine coal. A mathematical model has been developed to characterize the separation behavior of a typical high ash coal in a spiral. The modeling framework consists of parametric representation of geometry of the spiral and its trough, particulate flow along the helical path and principal forces acting on a particle during its motion. The elements have been combined seamlessly by assuming that the particles eventually attain dynamic equilibrium in the forward longitudinal direction and static equilibrium in the tra...
The aim of the present study is the simulation of the particulate flow in spiral separators. The study is based on Eulerian approach and turbulence modeling. The results focus on particulate-flow characteristics such as the velocity, the distribution, and concentration of particulates on the spiral trough. The predicted results are compared with the experimental findings from LD9 coal spiral. The comparison shows good agreement and indicates that the most accurate turbulence model is RNG K-e.
Ultrafine coal cleaning using spiral concentrators
Minerals Engineering, 2007
The conventional circuit fine coal circuit typically incorporates spiral concentrators to treat nominal 1 • 0.15 mm material. Pilot and in-plant studies have been performed to determine the operating parameter values needed to achieve optimum separation performances when extending the lower limit of a conventional spiral concentrator to 44 lm. Based on experimental and empirical data, a feed solids concentration of about 12% by weight is required with a feed rate of around 60 l/min per start. Under these conditions, 60% of the ashforming minerals and 48% of the sulfur was rejected from the 210 • 44 lm size fraction of a given coal source.
Development and Demonstration of an Automation and Control System for Coal Spirals
International Journal of Coal Preparation and Utilization, 2014
Coal spirals are widely used in coal preparation plants in Illinois and around the world to clean fine coal, typically in the 1 x 0.15 mm size range. Despite their popularity and the trend toward increased automation in modern coal preparation plants, adjustments to the critical process variable for coal spirals, i.e., product splitter position, continue to be done manually. Since spiral feed in a plant tends to fluctuate on a regular basis, suitable manual adjustment of splitter position in tens or hundreds of spirals operating in a plant is nearly impossible. As a result, the clean coal yield from a spiral and also the overall plant suffers on a regular basis.