کارایی متالورژیکی

The cleaner circuit at Miduk copper concentrator consists of 3 parallel flotation columns (4m in diameter and 12m in height). The cleaner concentrate is re-cleaned by 3 parallel flotation columns (3.2m in diameter and 12m in height), when the desired concentrate grade is not reached by the cleaner columns alone. This research work deals with simulation of the cleaner column flotation circuit at Miduk copper concentrator using USIM PAC simulator with the aim of improving the process metallurgical performance. For that purpose, the parameters of the models including flotation rate constants (kf, ks), residence time distribution (RTD), gas hold-up in collection zone (εg), mean bubble size (db), collection (Rc) and froth (Rf) zone recoveries along with some operating and geometrical variables were determined. The flotation rate constants were calculated by fitting the experimental data to the fast and slow floating components model. The residence time distribution of the flotation columns was measured by the tracer injection technique (using saturated NaCl solution as tracer). The gas hold-up and mean bubble size in the collection zone of the cleaner columns were estimated from the pressure difference and the drift flux techniques, respectively. The froth recovery was quantified by measuring the concentrate mass flow rate at different froth depths and extrapolation to the zero froth depth. The cleaner circuit was sampled five times, of which three times were used for calibration and two times for validation of the models. The mass flow rate, copper content and size distribution of the cleaner columns concentrate and tailings were accurately predicted using the simulation models. Increasing the number of operating cleaner columns improved the copper recovery (from 45.67% to 54.64%) at the expense of a reduction in the final concentrate (from 26.17% to 24.22%). The number of recleaner stages in all cases improved the the final concentrate (from 26.17% to 36.99% in the circuit with 2 cleaners and from 24.22% to 36.13% in the circuit with 3 cleaners). Increasing the feed slurry solids concentration reduced the size-by-size fractional copper recovery of the cleaner columns. Increasing the feed slurry solids concentration reduced the cleaner columns copper recovery in all size fractions. The best configuration of the cleaner and recleaner flotation columns was proposed.

Flotation is the most commonly used process for desulfurization of iron concentrates in iron beneficiation plants. The current study deals with improving the metallurgical performance of the flotation circuit at Sangan iron beneficiation plant. A plant survey indicated that sulfur content of iron concentrate is sometimes higher than that of the permitted limit used for the pelletizing plants (<0.25%). For this purpose, laboratory and full-scale experiments were carried out. In the batch flotation tests, the effect of collector dosage (65-105 g/t), frother dosage (45-75g/t), pH (6-10) and slurry solid content (27-33%) was examined against sulfur recovery. The results showed that the collector dosage, pH, frother dosage and slurry solids% are the most significant parameters in terms of sulfur recovery, respectively. The metallurgical performance improved with increasing the collector and frother dosage as well as reducing the pH. In the plant site tests, the influence of collector distribution method in the flotation circuit, collector dosage (65-105 g/t), frother dosage (37-85 g/t) and slurry solids% (25-33 g/t) on the flotation circuit performance was investigated. The results indicated that the optimum metallurgical performance was achieved when collector addition is divided into three parts: 50% was added to the rougher feed, 30% to the cleaner feed and 20% to the scavenger feed. Increasing the collector and frother dosage resulted in an increase in the sulfur recovery and a reduction in iron concentrate sulfur content. Increasing the slurry solids% was found to be beneficial to the sulfur recovery and detrimental to the quality of the product.