Simulation of a gravity processing circuit for low-grade chromite ores of the Gaft deposit (Iran)

Abstract

The purpose of this study was to design and simulate portable processing circuits for low-grade chromite ores with minimal equipment requirements. The studies were conducted using a chromite sample with Cr2O3 = 24 %. The efficiency of various types of process equipment, including dense medium cyclones, spiral separators, and hydrocyclones, for the separation of chromite from associated minerals was investigated, with due account of the difference in particle sizes and density of the major minerals in the sample, including chromite, dunnite, serpentine, peridotite, magnesite, and talc. Dense medium tests for the three particle size ranges of 1–2, 2–4.75, and 4.75–9.5 mm were carried out in solutions of bromoform (2890 kg/m3) and methylene iodide (3300 kg/m3). In all dense medium tests, the highest grade and recovery values were obtained for the solution with a density of 3300 kg/m3. When chromite particles of –1 mm were processed in a spiral separator, the Cr2O3 grade and recovery in the product were 50.51 and 54.40 %, respectively. Fine particle separation in a hydrocyclone rendered the underflow with d50 = 270 μm and Cr2O3 = 41.10 %. As a result of the laboratory-scale tests, a processing circuit with an input capacity of 10 t/h was designed utilizing MODSIM simulation software. The simulated lowgrade chromite ore processing circuit yielded concentrate with a Cr2O3 grade of over 39 % and a recovery of 50 %.