Iron Removal Process for High-Purity Silica Sands Production by Oxalic Acid Leaching

Abstract

In this article, a leaching study, carried out on a quartz sample to obtain high-purity silica sands, has been presented. A leaching process by using oxalic acid to remove low iron content from the ore under study and to obtain a material suitable for fiber optic production has been evaluated. A characterization study has been carried out to establish the location of the iron impurities on the ore: 77 g/t was the maximum iron contamination, whereas, a final iron content <10 g/t (as Fe) has to be achieved for the application considered. The effect of the grinding process on the iron extraction yield has been established; the maximum iron extraction yield obtained with the ore as-is was about 45−50%, whereas extraction yields greater than 80−90% can be obtained after grinding the ore in different experimental conditions. An empirical model was evaluated to correlate the iron extraction yield obtained after 3 h of leaching at 80 °C, with 3 g/L of oxalic acid and 10% (w/v) of ore concentration, as a function of the average particle diameter of the ore after grinding. An iron extraction yield of about 98−100% can be obtained with an average particle diameter of about 20 μm. A schematic flowsheet of the process has been proposed considering the obtained experimental results and the results obtained in the literature for the waste treatment aspects. The experimental results have shown the technical feasibility of this process for the production of high-purity silica sands.

A New Experimental Approach to Improve the Quality of Low Grade Silica; The Combination of Indirect Ultrasound Irradiation with Reverse Flotation and Magnetic Separation

“…In addition, there are recorded efforts to improve iron removal from silica by using Cyclojet or pneumatic flotation cells [15,16]. The last step for iron removal from silica is leaching, and many works have been conducted to investigate iron removal from silica [17][18][19][20][21]. It should be mentioned that some efforts were made to remove iron from relatively low grade silica using different reagents (H 2 SO 4 , HCl, and oxalic acid) in leaching experiments [1,6,22,23].…”

Chemical Evaluation of the Glass Making Potentials of Silica Sand Deposits Along Cross River in Cross River State, South–East of Nigeria

“…For a particular source of silica sand to be suitable for glass making, it must not only contain a very high proportion of silica but also should not contain more than strictly limited amounts of certain metallic elements [11]. Presence of iron in silica sand makes the resulting glass to be coloured and the iron level is consequently the most critical parameter in determining whether particular sand is good for making clear or coloured glass [36].…”

Submerged production of oxalic acid from glucose by immobilized Aspergillus niger

“…These activities have initiated studies directed towards utilization of this acid in hydrometallurgy for improvement of clays, kaolins, quartz and silica sands through dissolution of iron mineral impurities [5][6][7][8][9][10][11]. Remediation of metal-contaminated soils with oxalic acid producing fungi has also been contemplated [12].…”