Can Hydrocyclone be an Alternative in solid-liquid Separation Process?

In mineral processing industry, most of the separation processes involve substantial quantities of water. The final concentrate generated has to be with low moisture content and recovery of water from the tailing stream has to be recycled. So dewatering i.e., separation of liquid from solid is an important step in mineral processing. As dewatering processes are expensive and inefficient in general, these need focused attention. In case of fine and ultra-fine particles, (fine <100µm, ultra-fine < 5 µm) screening, even if in wet condition, is not effective. As there are many limitations associated with thickeners and filtration units, hydrocyclone can be thought of as an alternative in the solid-liquid separation process. Because of the design and operational simplicity, high capacity, low maintenance and operating cost, hydrocyclone is found to be very attractive for dewatering purpose. So, if hydrocyclones can be used efficiently at this stage, then the load on filtration units or thickeners can be reduced. This paper is aimed at understanding the most important factors that are affecting the separation of solid and liquid in a hydrocyclone for dewatering application i.e., recovering maximum solid and minimum water in the underflow which means maximum water recovery in the overflow. In this study the effect of three parameters on dewatering efficiency was studied in a 2″ hydrocyclone keeping at maximum pressure to achieve the objective. From the experimental results on silica sand, it was found that maximum 98.6 % solid can be recovered with 42.6 % water in the underflow

Studies on the cleaning potentialities of non-coking coal by washability study

Coking coal is the primary prerequisite source for the production of iron and steel through blast furnace route. Efforts have been made to correct the imbalance between need and availability of coking coal. This can be done by blending coking coal with either non-coking coal or semi-coking coal. To search for the above possibility systematic investigation of coals is required. Before going for any beneficiation studies for upgrading the coal (to reduce the ash level), washability study of the sample is required. The washability study of coals is performed through sink-float test in laboratory. Sink-float tests are widely used for coal analysis, to predict the theoretical yield and ash contents of clean coal obtainable in an ideal gravity concentrator at different specific gravities. It is a common practice to plot a series of ‘washability curves’, from the sink-float data of a coal sample in order to generate many useful information relating to its amenability for producing clean coal of desired quality. In this article a systematic investigation of washability study of non-coking coal from eastern region is studied through laboratory sink float test. From the washability study it has been found that 17% to 20% ash level can be achieved with a yield of ~30 to 33%%. Based on the data a suitable beneficiation scheme can be suggested

Processing of Fine Grained Iron Ore and Coal Samples Using Multi-Gravity Separator

One of the major problems of gravity based methods has been their limitation in treating particles in relatively fine size range. However, application of centrifugal forces in some of the recent gravity separators (e.g. Kelsey Jig, Knelson Concentrator, Falcon Concentrator, Multi-gravity Separator etc.) have been developed that can treat particles of much lower sizes. Development of Multi-Gravity Separator (MGS) by M/s Richard Mozley Limited, U.K. is considered to be one of the potential equipment for the treatment of fines and ultra-fines in the range of 500-1 micron. This paper deals with the results of studies carried out on recovery of mineral values from typical Indian iron ore slimes and coal fine samples using this equipment. In case of iron ore slimes, assaying 7.49% Al2O3 with 68% particles passing below 44 micron, it was possible to reduce alumina ~2% with a yield of 42%. Similarly, the clean coal products of coking and non-coking coal fines samples resulted in ash contents of 16.43% and 31.55% with yields of 47.3 % and 83.5% respectively

Amenability to Processing of Maganiferous Iron Ore

Manganiferous iron ore from Karnataka state was investi-gated to upgrade the iron content with lowering of mang-anese in concentrate. Mineralogical studies show that it is comprised of microplaty hematite, martite, goethite, pyrolusite, cryptomelane and minor amount of quartz and kaolinite. The sample contains about 51.4% Fe, 4.75% Mn with 8.5% SiO2 and 2.8% Al2O3. The crushed to 1mm and 3mm samples were subjected to reduction roasting using produ-cer gas. The reduction roasting converts the hydrated iron oxide mineral into more magnetic materials which facilita-tes the magnetic separation at low intensity leaving manganese minerals in non-magnetic. The reduced products were subjected to magnetic separation at very low magnetic field to recover magnetite. The final concentrate contain-ing 64.1% Fe and 2.3% Mn is achieved with a yield of 73.5% from -1mm sample. This product can be blended with the low Mn- hematitic concentrate with 65% Fe to generate a pellet feed

Characteristics of Iron Ore Slime from Kiriburu, India

The mineralogical, size and chemical characteristics of slime vary from discharge point to the distal part of the Tailing pond of Kiriburu iron ore mines. They can be grouped as three end members of slime composition- (i) coarse grained dense martite microplaty hematite type, (ii) coarse to medium grained goethite and clay dominated martite hematite type, (iii) fine grained hematite-goethite-clay type, occurring systematically away from the discharge point. Any slime will have a bulk composition intermediate to these three end members. The study has significance in the planning for exploitation of slime

High intensity magnetic separation of iron ore slime and its limitations

India is endowed with large reserves of high grade hematitic iron ores. However, steady depletion of these iron ores is now a concern forcing to develop beneficiation strategies to utilize low grade iron ores. In India, iron ores are generally washed to remove the high alumina containing clayey matter. Conventionally, after washing, the lumps are directly fed to blast furnace and the fines are used after agglomerating them into sinter. However, the slimes are being rejected in the tailing ponds. These slimes in most cases contain substantial iron values in the range of 54–58% Fe. Therefore, it is imperative to recover iron values from these slimes because of high demand on the good grade iron ores day-by-day. Also, it is expected that the iron bearing minerals will be in liberated state in the slime because of their fine particle size and will be amenable to beneficiation. National Metallurgical Laboratory is engaged in developing strategies for beneficiating iron ore slimes and during one such beneficiation studies, the slimes were processed through gravity and magnetic methods of separation. The slime under investigation contains Fe 58.64%, SiO2 3.41%, Al2O3 4.85% and LOI 7.57%. The mineralogy of the slime sample though indicated that hematite is the major iron bearing phase, goethite also occurs in substantial quantity. A systematic study on this slime sample using wet high intensity magnetic separation at higher intensities was carried out and the products were analyzed both chemically and mineralogically. The results indicated that stage wise magnetic separation with increasing intensity improves the total iron recovery. However, increasing the intensity over 1.31 Tesla again deteriorates the grade of the product. The results of this investigation are presented in this paper

Heavy Minerals and the Characters of Ilmenite in the Beach Placer Sands of Chavakkad-Ponnani, Kerala Coast, India

Indian beach placer sand deposits are, in general, ilmenite-rich. However, some concentrations are dominated by pyriboles. The Chavakkad-Ponnani (CP) area along the northern Kerala coast is one such deposit. This paper deals with the general character of the heavy minerals of CP with special emphasis on the characters of ilmenite. Most Indian beach sand ilmenites are of good quality. However, our observations on the ilmenites of CP using Optical Microscope, SEM and EPMA reveals that these are mineralogically very complex. The CP ilmenite varies from pure ilmenite to highly impure variety having intergrowths and inclusions of other oxide and silicate minerals. Ilmenite occurs as mix-crystals and forms intergrowth structure with hematite and Ti-hematite/ulvöspinel; contains inclusions of hematite, quartz, and monazite. On the other hand ilmenite also occurs as inclusions within hematite and garnet. The pyriboles are dominantly amphiboles with hornblende-composition. Interestingly an inclusion of gold has been recorded within amphibole of hornblende composition. Garnets are mostly of almandine and pyrope type. Subordinate heavy minerals sillimanite, zircon and rutile. Characteristic morphology, mineralogy and chemistry of amphibole, garnet and ilmenite together indicate that the placer sands of CP area are derived from the amphibolites, granite gneisses and basic igneous rocks lying in the hinterland towards the eastern border of Kerala. Though the overall quality of ilmenite is poor, high-grade ilmenite concentrate can be generated (of course with lower yield), by adopting precise mineral processing techniques. The CP deposit can be considered as a second-grade deposit but it has potential for future exploitation

Beneficiation of High-alumina Bearing Iron-ore Slime: A Case Study From Eastern India

A typical high-alumina containing iron ore slime from the eastern Indian sector containing 58.13% Fe, 6.48% SiO2, 4.9% Al2O3, and 5.35% LOI, have been evaluated to find out whether grinding of the slimes will be beneficial or not for upgrading the slime to generate pellet-grade concentrate with >64% Fe. Liberation studies indicated that there is significant interlocking between the minerals above 0.074 mm and hence grinding was adopted to liberate the minerals. It is found that by one-stage grinding, followed by hydrocycloning and magnetic separation by wet high intensity magnetic separator (WHIMS) can produce desired concentrate with >64% Fe with an yield over 60%

Artificial neural network modeling and experimental investigation to characterize the dewatering performance of a hydrocyclone

Dewatering in mineral processing industries is of paramount importance as most wet beneficiation of minerals needs removal of water. For this purpose, we have evaluated a 50.8 mm diameter hydrocyclone in order to assess whether it can be used as a partial replacement for a thickener. A multi-layer perceptron based artificial neural network (ANN) model was developed to characterise the dewatering performance of a hydrocyclone using experimentally generated data for silica and magnetite. Parametric sensitivity analysis was undertaken by studying the influence of vortex finder diameter, spigot diameter and inlet pressure on dewatering performance. The ANN model predictions showed that solid recovery to underflow increases and water recovery to overflow decreases with increasing spigot diameter whereas solid recovery to underflow decreases and water recovery to overflow increases with increased vortex finder diameter. Both increase monotonically with increase in inlet pressure. The neural model prediction was successfully validated with the experimental data