Operational optimization of copper flotation process based on the weighted Gaussian process regression and index-oriented adaptive differential evolution algorithm

Concentrate copper grade(CCG)is one of the important production indicators of copper flotation processes,and keeping the CCG at the set value is of great significance to the economic benefit of copper flotation industrial processes.This paper addresses the fluctuation problem of CCG through an operational optimization method.Firstly,a density-based affinity propagationalgorithm is proposed so that more ideal working condition categories can be obtained for the complex raw ore properties.Next,a Bayesian network(BN)is applied to explore the relationship between the operational variables and the CCG.Based on the analysis results of BN,a weighted Gaussian process regression model is constructed to predict the CCG that a higher prediction accuracy can be obtained.To ensure the predicted CCG is close to the set value with a smaller magnitude of the operation adjustments and a smaller uncertainty of the prediction results,an index-oriented adaptive differential evolution(IOADE)algorithm is proposed,and the convergence performance of IOADE is superior to the traditional differential evolution and adaptive differential evolution methods.Finally,the effectiveness and feasibility of the proposed methods are verified by the experiments on a copper flotation industrial process.

Occurrence mechanism of silicate and aluminosilicate minerals in Sarcheshmeh copper flotation concentrate

The Sarcheshmeh copper flotation circuit is producing 5× 10^4 t copper concentrate per month with an averaging grade of 28% Cu in rougher, cleaner and recleaner stages. In recent years, with the increase in the open pit depth, the content of aluminosilicate minerals increased in plant feed and subsequently in flotation concentrate. It can motivate some problems, such as unwanted consumption of reagents, decreasing of the copper concentrate grade, increasing of Al2O3 and SiO2 in the copper concentrate, and needing a higher temperature in the smelting process. The evaluation of the composite samples related to the most critical working period of the plant shows that quartz, illite, biotite, chlorite, orthoclase, albeit, muscovite, and kaolinite are the major Al2O3 and SiO2 beating minerals that accompany chalcopyrite, chalcocite, and covellite minerals in the plant feed. The severe alteration to clay minerals was a general rule in all thin sections that were prepared from the plant feed. Sieve analysis of the flotation concentrate shows that Al2O3 and SiO2 bearing minerals in the flotation concentrate can be decreased by promoting the size reduction from 53 to 38 μm. Interlocking of the Al2O3 and SiO2 bearing minerals with chalcopyrite and chalcocite is the occurrence mechanism of silicate and aluminosilicate minerals in the flotation concentrate. The dispersed form of interlocking is predominant.

Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains and microbial community succession analysis

Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains was carried out by mixed cultures on a small scale over a period of 210 d. Lump ores as a framework were loaded at the bottom of the ore heap. The overall copper leaching rates of tailings and lump ores were 57.10wt% and 65.52wt%,respectively. The dynamic shifts of microbial community structures about attached microorganisms were determined using the Illumina Mi Seq sequencing platform based on 16 S rRNA amplification strategy. The results indicated that chemolithotrophic genera Acidithiobacillus and Leptospirillum were always detected and dominated the microbial community in the initial and middle stages of the heap bioleaching process; both genera might be responsible for improving the copper extraction. However,Thermogymnomonas and Ferroplasma increased gradually in the final stage. Moreover,the effects of various physicochemical parameters and microbial community shifts on the leaching efficiency were further investigated and these associations provided some important clues for facilitating the effective application of bioleaching.

Experimental investigation and adaptive neural fuzzy inference system prediction of copper recovery from flotation tailings by acid leaching in a batch agitated tank

The potential of copper recovery from flotation tailings was experimentally investigated using a laboratory-mixing tank. The experiments were performed with solid weight percentages of 30 wt%, 35 wt%, 40 wt% and 45 wt% in water. The measurements revealed that adding sulfuric acid all at once to the tank rapidly increased the efficiency of the leaching process, which was attributed to the rapid change in the acid concentration. The rate of iron dissolution from tailings was less than when the acid was added gradually. The sample with 40 wt% solid is recommended as an appropriate feed for the recovery of copper. The adaptive neural fuzzy system(ANFIS) was also used to predict the copper recovery from flotation tailings. The back-propagation algorithm and least squares method were applied for the training of ANFIS. The validation data was also applied to evaluate the performance of these models. Simulation results revealed that the testing results from these models were in good agreement with the experimental data.

Flotation of copper oxide minerals:A review

Copper oxide minerals are important copper resources,which include malachite,azurite,chrysocolla,cuprite,etc.Flotation is the most widely used method for the enrichment of copper oxide minerals in the mineral processing industry.In this paper,the surface properties of copper oxide minerals and their effects on the mineral flotation behavior are systematically summarized.The flotation methods of copper oxide minerals and the interaction mechanism with reagents are reviewed in detail.Flotation methods include direct flotation(using chelating reagents or a fatty acid as collector),sulfidization flotation(using xanthate as collector),and activation flotation(using chelating reagents,ammonium/amine salts,metal ions,and oxidant for activation).An effective way to realize efficient flotation of copper oxide minerals is to increase active sites on the surface of copper oxide minerals to enhance the interaction of collector with the mineral surface.Besides,various perspectives for further investigation on the efficient recovery of copper oxide minerals are proposed.

Adsorption behavior and mechanism of copper ions in the sulfidization flotation of malachite

Malachite is one of the main minerals used for the industrial enrichment and recovery of copper oxide resources, and copper ions are unavoidable metal ions in the flotation pulp. The microflotation, contact angle, and adsorption experiments indicated that pretreatment with an appropriate concentration of copper ions could improve the malachite recovery, and the addition of excess copper ions reduced the hydrophobicity of the malachite surface. The results of zeta potential tests indicated that sodium sulfide and butyl xanthate were also adsorbed on the surface of malachite pretreated with copper ions. X-ray photoelectron spectroscopy(XPS) results indicated that —Cu—O and —Cu—OH bonds were formed on the surface of the samples. After pretreatment with an appropriate concentration of copper ions, the number of —OH groups on the mineral surface decreased, whereas the number of Cu—S groups on the mineral surface increased, which was conducive to the sulfidization of malachite. After adding a high concentration of copper ions, the —OH groups on the mineral surface increased, whereas the number of Cu—S groups decreased, which had an adverse effect on the sulfidization flotation of malachite. Time-of-flight secondary ion mass spectrometry showed that pretreatment with copper ions resulted in a thicker sulfidization layer on the mineral surface.

Hydrophobic-surface of copper from converter slag in the flotation system

The converter slag from a smeltery in Daye contains 2.01% copper.The floatability of copper has a significant influence on the flotation of converter slag.Flotation tests,contact angle tests and FTIR were conducted to assess the influences of pH and different flotation concentrators on its hydrophobic process,mechanism and flotation.The results show that since chemisorptions are formed on the surface,hydrophobicity of copper is highly enhanced by xanthate,butylamine dithiophosphate and Z-200.The hydrophobic-surface of copper becomes worse with low recovery in strong acid and alkali situation.When pH value is 10,butylamine dithiophosphate and butyl xanthate are used as the mixed-collector,the grade of copper is 40.01%and that of tailings is 0.37%.

Investigating the first-order flotation kinetics models for Sarcheshmeh copper sulfide ore

This study was performed in two phases of work.In the first stage,four conventional first-order flotation kinetics models were fitted to the measured recoveries data and the best model were selected.In the second stage,influence of pH,solid concentration,water chemistry and the amount of collector dosage were investigated on kinetics parameters including flotation rate constant and ultimate recovery.The results indicated that that perfectly mixed reactor model and Kelsall model gave the best and the weakest fit to the experimental data,respectively.It was observed that flotation rate constant and ultimate recovery were strongly affected by chemical factors investigated especially water quality.The flotation rate constant decreased with increasing the solids content,while ultimate recovery increased to certain value and thereafter reduced.It was also found that the most values of flotation rate constant and ultimate recovery obtained in dosage of collector are 30 and 40 g/t,respectively.

Optimization of reagent dosages for copper flotation using statistical technique

The effects of Z11 and AP407 collectors as well as AF65 and AF70 frothers were evaluated in the rougher flotation circuit of the Sungun copper concentrator plant using 2 4 full factorial design.Response functions were produced for both Cu grade and recovery and optimized within the experimental range.The optimum reagent dosages were found to be 12.01 g/t Z11,11 g/t AP407,3 g/t AF65 and 5 g/t AF70 to attain the maximum Cu grade(8.17%).The reagent dosages of 12 g/t Z11,11 g/t AP407,3 g/t AF65 and 15 g/t AF70 produced the maximum Cu recovery(86.44%).The collector distribution demonstrated that the distribution pattern of(32%,32%,20%,16%)can produce the best recovery(87.75%)in comparison to other examined distribution patterns.

Process mineralogy of copper-nickel sulphide flotation by a cyclonic-static micro-bubble flotation column

In our study we investigated a refractory copper-nickel sulfide ore separation by using a cyclonic-static micro-bubble flotation column (FCSMC). The process mineralogy of the main products was studied. Using a scanning electron microscope-energy dispersive system (SEM-EDS) and an X-ray spectrometer the mineral category and content of samples were analyzed. By using a mineral liberation analyzer (MLA) the mineral liberation characteristics were revealed. It is shown that in roughing feed the monomers liberation degree of nickel pyrite and chalcopyrite take up 84.11% and 88.82%, respectively. In tailings, the lost nickel pyrite and chalcopyrite are mainly monomers. Therefore, strengthening the micro-fine particle recovery capacity is the key to increase recovery.

Recovery of Copper and Cobalt from Converter Slag with a New Flotation Method Using H_(2）S

In this study,two different samples were obtained from Küre Copper factory.It was determined that the samples contain:the sample of K.C.F.(Küre Copper Factory),0.70%Cu and 0.5%Co.This sample was firstly grounded at-100 mesh dimension.Flotation was done according to previously obtained optimum flotation conditions.The flotation yield of Cu and Co in concentrate phase was found to be low by collective flotation.Even when the samples were grounded at-160 mesh,no change was observed in the flotation result.Especially,Co could not float under the flotation conditions of the non-sulfurized samples.There,a new flotation method was applied which was not applied until now.For this aim,the samples were firstly sulphurised under the steam of H2S+H2O.By this method,the amount of Cu and Co in the samples get rich.According to the obtained results,the optimum reactions for flotation and sulphurization were determined.In the first sulphurization conditions for the sample of K.C.F.,the yield of flotation for the Co and Co were found to be 98.27%and 68.07%,respectively.The results indicate that Cu can be floated at low yield in the original samples.On the other hand,Co cannot float under these conditions.

Estimation of Copper and Molybdenum Grades and Recoveries in the Industrial Flotation Plant Using the Artificial Neural Network

In this paper, prediction of copper and molybdenum grades and their recoveries of an industrial flotation plant are investigated using the Artificial Neural Networks (ANN) model. Process modeling has done based on 92 datasets collected at different operational conditions and feed characteristics. The prominent parameters investigated in this network were pH, collector, frother and F-Oil concentration, size percentage of feed passing 75 microns, moisture content in feed, solid percentage, and grade of copper, molybdenum, and iron in feed. A multilayer perceptron neural network, with 10:10:10:4 structure (two hidden layers), was used to estimate metallurgical performance. To obtain the optimal hidden layers and nodes in a layer, a trial and error procedure was done. In training and testing phases, it achieved quite correlations of 0.98 and 0.93 for Copper grade, of 0.99 and 0.92 for Copper recovery, of 0.99 and 0.92 for Molybdenum grade and of 0.99 and 0.94 for Molybdenum recovery prediction, respectively. The proposed neural network model can be applied to determine the most beneficial operational conditions for the expected Copper and Molybdenum grades and their recovery in final concentration of the industrial copper flotation process.

SYNERGISTIC ACTIVATION OF CHELATING AGENT ON XANTHATE DURING THE FLOTATION OF REFRACTORY COPPER OXIDIZED ORES

For realizing the effective flotation of refractory copper ox-idized ores and developing the activation-flotation theory , the influences of nine different organic chelating agents on xanthate collection pcnver and its adsorption characteristics ivere studied in the flotation of malachite and chrysocolla representatively selected by means of XPS,IR, absorbed quanti-ty measurements and flotation tests.For easily-dissolved malachite flotation , a small amount of chelating agent can obviously enhance xanthate collecting power and make malachite floated easily , and so reduces the consumption of xanthate. For hard-dis-晄olved chrysocolla, chelating agent is able to increase its recovery to 90% , but the chelating agent consumption is high. Chelating agent and xanthate can produce synergistic adsorptions, which follmv Freundlich's adsorption equation on malachite and Chrysocolla surfaces. The high chemical activity of chelating agent and its synergistic activation on xanthate are the key to improving xanthate collection poiver. The synergistic activation of chelat-ing agent on xanthate on melachite surfaces is clearly stronger than on chrysocolla surfaces. According to experimental results, it can be thought that the synergistic activation results from the synergistic complexation of chelating agent and xanthate with copper ions to form biligand-tribasic co-ordination complex.

Effect of Flotation Reagents on the Cake Moisture of Copper Concentrate

The effect of reagents used in separating chalcopyrite from pyrite on the cake moisture of the copper concentrate at Daye Iron Mine Mineral Processing Plant was investigated. The results showed that the dosage of lime used for depressing pyrite was the main factor that increased the filter cake moisture of copper concentrate. With increasing the dosage of lime, the cake moisture of copper concentrate increased sharply. The cause was concluded to be the addition of lime to the pulp, which resulted in the formation of floc and a high pH value. The collector Z-200#, used for collecting chalcopyrite, had, as well, an adverse effect on the cake moisture of copper concentrate, but its effect was inferior in respect to that of lime. The cake moisture of copper concentrate can be decreased by changing the method with which lime is added and the pH value of pulp is regulated. The experiment results showed that the sulfuric acid was the best regulator. When the clarified liquor of lime was used as a depressant and the pH value of the pulp was regulated to 6.5€*7.0 by adding sulfuric acid, the cake moisture of copper concentrate was reduced from 15.49% to 13.13%. The examination of chalcopyrite surface by using ESCA (Electron Spectroscopy for Chemical Analysis) showed that calcium sulfate and iron hydroxide had formed on the surface of chalcopyrite when lime was added to the pulp. The formation of calcium sulfate and iron hydroxide on its surface increased the hydrophilicity of chalcopyrite so that its cake moisture increased. The addition of sulfuric acid to the pulp not only removed the calcium sulfate, but also reduced the concentration of iron hydroxide on the surface of chalcopyrite so that the cake moisture of copper concentrate was decreased.

Development of a Combined Flotation and High Pressure Leaching Process for Copper and Nickel Recovery from Mine Tailing

The present study focused on the re-processing of copper and nickel from mine tailings. In this work, recovery of copper and nickel from mine tailing by combined process of flotation and high pressure oxidative leaching were considered. In the first stage, effects of flotation parameters including collector type, collector dosage, and pH and pulp density were examined. The results showed that over 80% copper recovery was achieved under the optimized flotation conditions while nickel recovery was lower than 30% due to its co-ex-istence with gangue minerals of pyrrhotite, pyrite and other clay minerals. In the second stage, key parameters, particularly concentration of sulfuric acid, temperature, pressure and leaching time were investigated to test the leaching efficiency of copper and nickel from the flotation concentrate with high pressure oxidative leaching (HPOL). A comparison was made between the leaching efficiencies of copper and nickel from flotation concentrates and mine tailing.

Effect of Desliming on Flotation Response of Kansanshi Mixed Copper Ore

The Kansanshi mixed copper sulfide-oxide ore contains significant proportions of fine material manifesting in a variety of processing challenges. This paper presents the work which was carried out to evaluate the efficacy of desliming in improving the flotation response of the ore. Two modes of desliming were investigated, namely;sieving and elutriation after which the deslimed material was subjected to Kansanshi standard laboratory flotation conditions. The minimum copper feed grade for the mixed copper ore was 0.5% Total Copper (TCu). The outcome of this work has shown that desliming improves the flotation response of the Kansanshi mixed copper ore. At a rougher copper concentrate grade of 8%, copper metal recoveries obtained with desliming were in excess of 70% compared to 58% achieved with baseline tests without desliming. It was further observed that desliming resulted in improved flotation rates for the sulfide minerals. For a flotation time of 3 minutes, recoveries of 69% and 74% were obtained with elutriation and sieving respectively compared to 58% recovery for baseline tests. From the same results it was also evident that, of the two modes of desliming investigated, sieving yielded better performance than elutriation.

An electrochemical investigation on collectorless flotation of sphalerite in presence of Cu^(2+) ions

The collectorless flotation behaviors of sphalerite in the presence of Cu 2+ ions have been established. The effects of pH, potential and Cu 2+ concentration on the flotation have been studied using a micro flotation cell specially designed, where the potential can be controlled by a potentiostat. The flotation results have shown that the Cu activated sphalerite displays a good collectorless floatability in a pH range of 0～13. The higher potentials can improve the flotation recovery. The surface species formed during the Cu ion activation have been examined using a special electrochemical technique—a composite sphalerite electrode. Zinc deficient sulfide (Zn 1- x Cu x S) and Cu poly sulfide (Cu y+z S y ) species have been determined. They are responsible for the collectorless flotation of sphalerite. In additional, they can improve the conductivity of the sphalerite surface.

Indirect determination of cefradine with n-propyl alcohol-ammonium sulfate-water system by extraction-flotation of cuprous thiocyanate

A new method was developed for the determination of cefradine by extraction-flotation of CuSCN. The experiment indicated that in the presence of 0.20 mol/L NaOH the degradation of cefradine took place in water bath at 100 ℃. The thiol group （-SH） of the degradation product could reduce Cu（Ⅱ） to Cu（Ⅰ） for the formation of the emulsion CuSCN in the presence of NH4SCN at pH 4.0. By determining the residual amount of Cu（Ⅱ） in the solution and calculating the flotation yield of Cu（Ⅱ）, the indirect determination of cefradine can be obtained. This method has been applied to determine cefradine in capsules, human serum and urine samples, respectively.

The Effects of Water Recycling on Flotation at a North American Concentrator—Part 1

Water chemistry and its impact on mineral processing operations are not well understood and often not adequately monitored. CanmetMINING, as part of its water management research program, has been involved in a project initiated to identify opportunities for improving water recovery, water treatment, and recycling in the mining and mineral processing operations. One of the main objectives of this work is to evaluate and assess water chemistry and identify factors that impact mineral recovery, concentrate grade, and metal extraction efficiencies in order to understand and mitigate negative impacts of water recycling and improve process efficiency. In collaboration with a North American concentrator, CanmetMINING has been involved in assessing the water chemistry in the mill and evaluating water recycling options for select process streams to reduce fresh water intake and maximize recycling. The overall goal of the project is to investigate options for water recycling (increase the thickener overflow recirculation from thickener overflow tank) without affecting nickel and copper metallurgy. The results of the sampling campaigns showed that the water chemistry of the streams was fairly consistent throughout the year with no significant seasonal variations. The laboratory tests illustrated that when higher quantities of thickener overflow from thickener overflow were used, the nickel + copper grade versus nickel recovery curves shifted towards lower values. These observations were observed for the plant water samples obtained in April, June and August 2019.