فلوتاسیون

In the iron ore mines of Gol-Gohar, talc presents along with magnetite mineral, which goes to waste thickeners after recovery of magnetite. Considering that talc constitutes more than 20% of waste, it can be sold as a by-product with a high added value, if it is recovered and purified. In this study, the extraction of talc from the tailings of the Gol-Gohar complex has been investigated. Sampling was done from the central thickener underflow, which contained 65% of dust factory tailings and 35% of concentrate factory tailings. Based on characteristic studies, the tailings from the central thickener had about 23% talc. Flotation tests were performed using different chemicals, such as pine oil and polypropylene glycol as frothers, oleic acid as collector, Armac C and Armac T, and pH 7 and 11. In the best condition, pH=11, polypropylene glycol as a frother, and not using a collector, a talc concentrate with a purity of more than 95%, a weight recovery of 10.4%, and a talc recovery of 42% was produced. Also, flotation kinetic tests were performed under optimal conditions, and it was shown that most of the first-order kinetic models and the second-order kinetic model excellently match the talc flotation recovery over the time.

Kooshk mine is one of the largest lead-zinc deposits in Iran. A high amount of pyrite and carbonaceous matter are two distinct characteristics of the Koosh deposit. Therefore, the competition between sphalerite, galena, and pyrite minerals and their selective separation in flotation is significant. In this research work, due to the low recovery of lead in the Kooshk flotation circuit, the possibility of pyrite depression and improvement of lead recovery by using various depressants was investigated. Pyrite and sphalerite depressants in galena flotation were used, such as sodium cyanide, sodium sulfite, sodium metabisulfite, iron sulfate, dextrin, Quebracho, SHQ (40% sodium silicate + 40% sodium phosphate + 20% Quebracho) and A3-3 (40% sodium silicate + 40% sodium metabisulfite + 20% aluminum sulfate). The results showed that each depressant, except dextrin, SHQ, and A3-3, significantly affected pyrite and sphalerite floatability, and lead recovery improved at some point during their consumption. Sodium cyanide, sodium metabisulfite, and sulfate iron showed the most effect in the depression of pyrite. In addition to sodium cyanide, the maximum pyrite & sphalerite depression and the maximum lead grade & recovery were obtained with the separate consumption of 600 g/t ferrous sulfate and 200 g/t sodium metabisulfite. Compared to other non-toxic depressants, iron sulfate, and sodium metabisulfite made pyrite and sphalerite depressants more effective and increased lead recovery by up to 8%.

Froth recognizing as the output of the flotation process can be efficient in better control of this process. Since the physical structure of the froth indicates the operational conditions of the flotation cell, the quality of the separation can be estimated according to its characteristics. Technological advances have led to monitoring and control operations using online systems. Image analysis method is one of the growing methods in this field. In addition to control the structural changes of the concentrate, using a device that can measure the quality of the froth online and report it regularly can keep the amount of chemicals consumed in the cell at optimal levels, and provide stability in the separation efficiency of the flotation unit. In this paper, changes in the froth structure of cleaner cell of Sungun copper processing plant were investigated. The area, circumference, elongation and diameter of the bubbles and their distribution, which are structural features of the froth, were calculated online to control flotation cell changes and used to classify the froth. Froth images were clustered in three classes of dry, wet and stiff froth using K-means algorithm and two characteristics of bubble fret area and diameter. The results showed that in dry froth, bubbles of froth surface are in a wider range of dimensions. This type of froth is in optimal condition in terms of load, mobility, stability and structure, also the grade of this type of froth is in the range of 25 to 29. Though, unlike dry froth, wet and hard froths are not in optimal condition in terms of bubble load, mobility, stability and structure due to the use of more or less excessive chemical additives. Also, the grades of wet and hard froths are in the range of 22 to 27 and 20 to 24, respectively.

As the most important phosphate producer in Iran, the Esfordi phosphate complex produces apatite concentrate from the igneous ore by the flotation method. This plant is designed to separate phosphate from iron minerals. There is a type of rock in the Esfordi deposit that contains magnesium-bearing silicate minerals as gangue, which refers to green rock. Although the green rock includes five million tons of the mine reserve with an average grade of 7% P2O5, it has not been fed to the beneficiation plant, so far. In this research, the green rock processing was investigated using the current processing plant. A representative sample of green rock was prepared and characterized to evaluate the chemistry, mineralogy, and degree of freedom of apatite minerals. The laboratory magnetic separation and flotation tests along with the plenary sampling and characterization from the processing plant were performed. 

Esfordi Phosphate Mine has the largest reserves of igneous phosphate in the country. At present, the feed for the dressing plant is supplied from apatite and iron-apatite. The green rock is an alternative feed for the beneficiation plant. The presence of magnesium-bearing silicates and fine particles are the two main obstacles of green rock flotation. In this research, flotation experiments were performed to process green rock, and the performance of the current phosphate processing plant was assessed. 

Sampling was performed in two stages. In the first step, a sample was taken from the stock to identify the characteristics of green rock. The laboratory magnetic separation experiments at different magnetic field intensities and flotation experiments were performed. Fatty acid collector (to float apatite) and corn starch (for depressing iron ores and silicate minerals) were used in the flotation tests. The industrial-scale investigations were made by feeding the green rock to the plant, and sampling procedures were performed from different grinding, classification, and flotation streams. 

The results of High-intensity magnetic separation experiments showed that some of the silicate minerals found their way to the iron magnetic separation concentrate (recovery of 10.38% MgO at 5000 gausses). Flotation experiments showed that the recovery for green rock samples was very low and under normal conditions, recovery and P2O5 grades of 7.39 and 21.11% were gained, which increased to 38.65 and 27.98% after desliming. The efficiency of feeding green rock to the current circuit was monitored and low flotation recovery was observed along with high froth stability. The efficiency of the grinding circuit and desliming cyclones was also evaluated. Then, suggestions were made to improve the current processing circuit for green rock beneficiation.

Due to the widespread use of phosphate, there is a need for extensive studies and experiments in relation to its processing. In this research, flotation method was used to remove carbonate gang with the help of a collector made of G (j-mrap1). The grade of sedimentary ore of Charam phosphate mine used in this research is 13% P2O5 and it is considered as a low grade reserves and also its sub-minerals are 46% of calcite and 7% of silica. To achieve a commercial grade of 28% P2O5, a new collector with a hydroxamic acid operating group has been synthesized and used. By optimization by experimental design software (DX7), at pH equal to 6.2 and collector 1000 g / ton, the maximum recovery of 84.97% P2O5 with a grade of 27.71% P2O5 was achieved. By changing the pH to 6.5 and the amount of collector to 1200 g / ton, the concentrate with the highest grade was 29.47% P2O5 and 82.87% P2O5 was recovered. The use of plant-based synthesized collectors indicated that this type of collector could be a suitable alternative to chemical-based collectors.

Floatation behavior of apatite mineral from the surface and deep samples of polymetallic ores from Gharah-Aghaj Urmia was studied. Floatation experiments were performed in the form of an experimental design considering the pH, solid percentage, and collector consumption amount as variables, for two samples of mentioned surface and deep ores. Results of the experiments approved the feasibility of obtaining concentrate from both samples, but the qualities of concentrates are completely different and floatation behavior of apatite of deep sample is weaker compared with the surface sample. Analyzing the effect of variables on the resultant grade and recovery revealed that pH, solid percentage and collector amount have a negative effect on surface sample grade. However, in the deep sample, pH and solid content don’t have a significant effect on grade and the effect of collector amount on deep sample grade is positive. After optimization of floatation conditions for both samples, at optimized conditions, for the surface sample after a rougher stage and 5 cleaner stages, a concentrate with a grade of 33.23%% P2O5 and a recovery of 74.80%, and for the deep sample after 6 cleaner stages, a concentrate with a grade of 28.81% P2O5 and a recovery of 55.01% were obtained. Characterization revealed that deep concentrate has calcite and Magnesio-Hornblende which floats along with apatite and prevents the increase of the final concentrate grade. On the other hand, results of elemental analysis by EDX showed that the amount of fluorine element in the deep sample is lower in comparison to the surface sample, which is a reason for the low floatation strength of deep sample apatite. Finally, it has been concluded that in the Urmia Gharah-Aghaj ore deposit, as the depth increases the floatation efficiency of apatite decreases.