Magnetic separation studies for a low grade siliceous iron ore sample Dwari Ranjan Kumar, Rao Danda Srinivas ⇑ , Reddy Palli Sita Ram CSIR-Institute of Minerals and Materials Technology, Council of Scientific and Industrial Research, Bhubaneswar 751 013, India article info Article history: Received 2 May 2012 Received in revised form 3 June 2012 Accepted 1 July 2012 Available online 8 February 2013 Keywords: Iron ore Magnetite Characterization Dry and wet magnetic separation abstract Investigations were carried out, on a low grade siliceous iron ore sample by magnetic separation, to establish its amenability for physical beneficiation. Mineralogical studies revealed that the sample con- sists of magnetite, hematite and goethite as major opaque oxide minerals where as silicates as well as carbonates form the gangue minerals in the sample. Processes involving combination of classification, dry magnetic separation and wet magnetic separation were carried out to upgrade the low grade sili- ceous iron ore sample to make it suitable as a marketable product. The sample was first ground and each closed size sieve fractions were subjected to dry magnetic separation and it was observed that limited upgradation is possible. The ground sample was subjected to different finer sizes and separated by wet low intensity magnetic separator. It was possible to obtain a magnetic concentrate of 67% Fe by recover- ing 90% of iron values at below 200 lm size. Ó 2013 Published by Elsevier B.V. on behalf of China University of Mining & Technology. 1. Introduction Magnetic separation is an important beneficiation process and is usually adopted for ores of manganese, phosphate, titanium, chrome, tungsten, molybdenum, nickel, bauxite and niobium-tan- talum ores in addition to iron ores [1–15]. Magnetic separation methods were also carried out for the ferrochrome industry wastes such as the flue dust to find out the possibilities of partial recycling and or for the recovery of metal and chromite of significant value [16]. Magnetic separation is a simple, inexpensive, non-destructive and rapid means of concentrating iron-bearing minerals to nearly monomineralic levels, particularly those present in different pro- portions in clays. The use of variable magnetic flux density further allows sub-fractionation of the iron-bearing minerals [17]. The selection of magnetic separation techniques depends on many pro- cessing factors, such as assemblage of minerals, their liberation size, and their corresponding magnetic susceptibility in addition to production, marketing and environmentally friendly issues. Magnetic treatment of ores and industrial minerals is conducted in both wet and dry modes. The dry magnetic separation process only enables purification where as in the wet process the end prod- uct results in the form of slurry. The former especially applies when dealing with material with finer particle sizes. Many mineral processing industries want to purify the magnetic minerals from the non-magnetic portions by using the dry magnetic separation techniques. The wet and dry magnetic separation process has spe- cific advantages as well as disadvantages. Questions are often raised about which separation technique is most appropriate for a particular ore type or operation. The most suitable solution is commonly determined by the required specifications of the end product or a clean marketable product. The dry magnetic separa- tion techniques applied based on a number of reasons such as (i) local availability of water, (ii) cost of drying, (iii) demands of the end customer and (iv) ever changing environmental issues. With dry methods care must also be taken to ensure control of dust haz- ard, an expensive precaution both in capital and operating costs. Furthermore, dry separators have considerably lower throughputs than wet machines. Dry separators frequently yield excellent sep- aration of materials coarser than 75 lm. On the other hand, on an unsized material containing large portions of fines, the wet process is the only acceptable one. Generally, dry magnetic separation is used when relatively large volume of non-magnetic substances is usually the commercial products and the amount of magnetic materials removed is quiet small. Considerable advantages must, therefore, be offered by dry separation techniques to justify its use in preference to wet process. This present paper discusses both the dry and wet magnetic separation techniques used for process- ing of a low grade siliceous iron ore sample. 2. Materials and methods About 500 kg of a low grade siliceous iron ore sample was crushed to below 10 mm size by using jaw crusher. The crushed sample was thoroughly mixed and subjected for sampling by con- ing and quartering technique to prepare representative samples. These representative samples were used for different laboratory investigations. Dry magnetic separation method was adopted 2095-2686/$ - see front matter Ó 2013 Published by Elsevier B.V. on behalf of China University of Mining & Technology. http://dx.doi.org/10.1016/j.ijmst.2013.01.001 ⇑ Corresponding author. Tel.: +91 6742379476. E-mail address: dsrao@immt.res.in (D.S. Rao). International Journal of Mining Science and Technology 23 (2013) 1–5 Contents lists available at SciVerse ScienceDirect International Journal of Mining Science and Technology journal homepage: www.elsevier.com/locate/ijmst