Value addition processing of low grade iron ores Research Papers (original) (raw)

Supply of world chromite (chrome ore) has come under severe pressure over the past year driven by
strong demand for ferrochrome used in ferroalloy production for making stainless steel. Many of the strategic
minerals are inputs into products in fast-changing markets. This article reviews the major process
flow sheets in practice for the recovery of chromite values from various types of ores and critical issues
related to chromite ore beneficiation. The comprehensive condensation of pertinent facts is intended to
provide a single reference source rather than the reader perusing many articles. Emphasis is placed on
different processes developed in identifying and solving critical plant problems.

- by and +1
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- Mineral Processing, Manganese, Chromium, Value addition processing of low grade iron ores

This investigation compares bacterial leaching to chemical leaching to solubilize copper from a copper containing ore of the new site Northern Qarashoshaq in Zhylandy (Kazakhstan) which is currently under commercial development. From ICP-OES analysis the bulk ore sample contains 1.5% of Cu and a trace level at 0.0024 % of Ag. Phase analysis shows the main copper containing minerals are covellite, сhalcocite, malachite, chrysocolla and chalcopyrite. According to X-ray diffraction analysis silver is mainly presented as jalpaite (Ag3CuS2) minerals. Copper leaching was carried out by acidophilic bioleaching for comparison with extraction by chemical methods involving the addition of sulfuric acid and Fe3+ or only sulfuric acid in flasks, as well as column leaching tests to simulate heap leaching. Ag was extracted by cyanidation methods again in flasks as well as column leaching tests. Results showed that copper extraction is up to 95% when using bioleaching in the flask, 83% in the case of Fe3+ with sulfuric acid and 76% for sulfuric acid. Furthermore, subsequent extraction of Ag reaches 97% for bioleaching and 92% for chemical leaching. Column bioleaching tests showed an 82.3% yield of copper after 70 days of the experiment and a 70% of silver, whereas for chemical leaching the yield of copper is 66.8% and silver is 51%. In conclusion this investigation demonstrated higher extraction for both copper and silver from the primary ore in the bioleaching sample compared to the chemical leaching sample. More silver was extracted in the bioleaching case as there was less copper remaining to compete for the cyanide anions.

- by Simon R Collinson and +2
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- Bioleaching, Copper extraction and production, Copper, Silver

Although dicalcium silicates can constitute up to 10 vol% of many modern hematite/goethite iron ore sin- ters, traditional mineralogical investigations of such sinters have largely overlooked this phase and focused on the more abundant iron oxides and ferrites. However, dicalcium silicates have a range of properties that make them unique in sinter parageneses. These properties may contribute significantly to bulk sinter prop- erties and also make dicalcium silicates potentially exploitable in novel upgrading processes. Analyses on a pot grate test sinter have shown that phosphorous (and possibly other elements including potassium and chromium) was heavily concentrated in the dicalcium silicates. A series of etch tests have demonstrated that dicalcium silicates can be selectively removed from the surface of polished sinter samples using weak acids. In addition, bulk leaching trials showed that the phase can also be removed from powdered and coarser ( 5 mm) sinter in mild acids. These leaches resulted in a 90 % reduction in phosphorous with a 7 % improvement in iron grade for the powdered material and a 70 % reduction in phosphorous with a 5 % improvement in iron grade for the coarser material. Two novel processes are proposed to exploit the leacha- bility of contaminated dicalcium silicates from sinter: one being a potential route to a high-grade iron prod- uct, the other being a return fines washing circuit.

In India, iron ores processing industries play a vital role in the Indian economy. During the washing and processing of iron ores, slimes less than 0.15 mm are generated and discarded into the tailing pond. These slimes need processing as they cannot be used directly in blast furnaces. In the present investigation, a typical iron ore slime sample containing 59.22% Fe, 4.76% SiO2, and 4.57% Al2O3 was taken. The desliming operation was carried out by using 2” Mozley hydrocyclone. The process variables used to attain the optimum condition of desliming include the spigot opening, the feed pressure, and the diameter of the vortex finder maintaining the pulp density at 10% solid. The deslimed sample was treated by different techniques including an enhanced gravity separator to achieve iron concentrate with 65% Fe so that it can be used for steel making through pelletization. The yield of the magnetic concentrate is about 46.8% with 65% Fe. To improve the yield, the overflow from 2” hydrocyclone and the rejects from magnetic separation were deslimed and processed to recover the iron values. The final concentrate is 74% yield with 64.8% Fe, 1.76% SiO2, and 1.8% Al2O3.

Magnetite nanomaterials are immensely valuable in the biomedical, water science, electronic and bioengineering fields because of their para-magnetic property and biocompatibility. Nevertheless, the cost of these materials is very high although it is regularly used in most applications in modern industries. To address the issue, the present study is focused to synthesize magnetite nano-spheres assembled nano-architectures. The low cost and locally available laterite was used as a source of iron. The extracted iron was purified and converted into magnetite by a sol-gel synthesis method. The synthesized iron nanoparticles were characterized using X-ray diffraction (XRD), Scanning Electron Microscopic (SEM) and Thermogravimetric (TG) techniques. The obtained results confirmed that 50 nm of spherical magnetite particles were formed. Also, the particles showed some picturesque self-assemblies when the pH of the precursor-solution of the sol-gel process and the rate of annealing are changed. TG analysis reveals that the annealing temperature is 500°C. X-ray diffraction pattern of the product is comparable with commercially available nano-magnetite as well as the same material produced using chemicals using the same method. These prepared nano-architectures have potential applications in drug delivery, electronic devices and medical imaging.