Bottle Roll Research Articles

Analisis Pendekatan Nilai %Ekstraksi Ore North Mainrigde Dengan Metode Bottle Roller Test Di PT. J Resources Bolaang Mongondow

The heap leach method is one of the cyanidation processes suitable for low-grade ore and PT J Resources Bolaang Mongondow uses this method in its processing. Column test is the most representative testwork of the heap leach process, but this testwork requires a long time so a faster testwork is needed and can provide %extraction value even though it is less representative and bottle roll test (BRT) is a solution for this. This study aims to estimate the % extraction obtained in cells by the BRT method. From the experimental results, it was obtained that the %extraction value of HG 01 samples at +12, +6, and -6 sizes was 67.1%, 79.2%, and 92.4%, respectively. for LG 02 samples of 68.3%, 81.5%, and 93.9%, for LG 03 samples of 54.5%, 90.6%, and 89.6%, respectively, these three samples are categorized as med-high extraction. While the LG 04 sample was 67.3%, 66.3%, 84.8% and categorized as low extraction.

Investigating the benefits of using HPGR prior to cyanidation of low grade gold ore

AbstractIt is known that the cracked structure of the particles has positive effects in leaching processes. In this respect, high pressure grinding rolls (HPGR) provides some advantages such as increasing leaching efficiency and reducing leaching time by creating more cracked particles compared to other crushers. Although there are studies on the advantages of HPGR on different ores, these have not been fully demonstrated in low grade gold ores, and leaching kinetics have not been examined in detail in the studies conducted in this context. In this study, first of all, crack formation in a low grade gold ore by crushing with HPGR and jaw crusher was investigated. Then, bottle roll tests were performed in different size fractions and different cyanide concentrations along with column leaching of the pelletized ore in a single test condition. As a result of the studies, it was determined that 2–3 times more cracked particles were formed in HPGR depending on the particle size. It was shown that the modified Kelsall model explains the kinetics better than other kinetic models tested. In summary, it was revealed that maximum gold extractions are almost same for HPGR and jaw crushers. However, the fast dissolution kinetic constant was found to be around 25% higher for HPGR than for the jaw crusher in bottle roll tests while this ratio was approximately 30% higher in column leaching tests, suggesting a distinct influence of the crushing method on the dissolution kinetics.

Characterization of Gold in Complex Historical Refractory Tailings for Enhanced Process Optimization

ABSTRACT Historical gold tailings show promise as a secondary resource amid declining primary deposits, yet conventional cyanidation falls short, resulting in recoveries below 90%. An essential pre-treatment process is crucial for optimal recovery, contingent on understanding the complex mineralogy of the tailings. This study employs a multidisciplinary approach to thoroughly analyze gold’s refractory behavior in complex historical tailings. Using operational mineral fractions, cyanide bottle roll tests, aqua regia digestion, diagnostic leaching, and chemical and mineralogical analyses, the research draws material from Witwatersrand’s extensive tailings reservoirs. These reservoirs, exemplifying complexity, exhibit a recovery rate of less than 50% through cyanidation. Findings reveal limited cyanide-amenable gold, with recoveries ranging from 14–61% at ∼0.05 g/t, primarily as micron to nano-sized native gold particles hosted in the slimes mineral fraction (<40 µm). Higher susceptibility to cyanide leaching is observed in recoveries ranging from 14–74% compared to 10–54% in light mineral fractions (<2.95 g/cm3). Non-cyanide amenable forms, such as sulfides and silicates, contribute to refractory behavior at 4–38% (∼0.09 g/t) and 11–32% (∼0.05 g/ton) respectively, with varying gold distributions across different tailings dumps. This suggests that a pre-treatment step, combined with tailored leaching in the metallurgical flowsheet, would substantially improve gold recoveries beyond 60%. The investigations in this study provide a valuable analytical tool for determining the amenability of complex historical gold tailings to different pretreatments, optimizing gold recovery, contributing to sustainable resource management, and maximizing the utilization of this valuable gold resource.

Automated Mineralogy and Diagnostic Leaching Studies on Bulk Sulfide Flotation Concentrate of a Refractory Gold Ore

Obtaining detailed and precise information from a classified refractory gold ore has been a long-standing challenge in mineral processing and process mineralogy. Although the concept of diagnostic leaching has been extensively addressed in the literature, very little information is available linking this approach with current advanced characterization techniques such as automated mineralogy. The present research study aims to characterize the flotation concentrate of refractory gold ore by combining diagnostic leaching and automated mineralogy to examine its processability. The diagnostic leaching process was applied stepwise at five stages, and the automated mineralogy was performed on different size fractions of the flotation concentrate. The chemical (X-ray fluorescence (XRF), atomic absorption spectroscopy (AAS), and inductively coupled plasma-optical emission spectroscopy (ICP-OES)) and mineralogical (X-ray diffraction (XRD)) analyses of the feed sample confirmed that the ore is a low-grade gold ore with 0.7 g/t Au. Initially, bottle roll tests were carried out to investigate leaching behavior, and the ore’s refractory nature, and gold recoveries of bottle roll tests in different sizes were below 40 wt%; it is classified as a high refractory gold ore as a result of direct cyanide leaching. Bulk sulfide flotation was applied to increase the gold content of the material. Automated mineralogy results demonstrated that most of the gold in the concentrate is present as an invisible gold form, and 63.7 wt% of gold was distributed in pyrite. Diagnostic leaching results showed 39.7 wt% of total gold was leachable using direct cyanide leaching, and around 33 wt% of undissolved gold was located in pyrite and arsenopyrite.

Design and Manufacturing of Bottle Roller Machine for Laboratory Leaching Process by Using Recycled Materials

Bottle roll is the equipment used for laboratory metal leaching tests. Leaching is a widely used metal extraction process by dissolving metal from ore using certain chemical reagents. The working principle of the bottle roll is to stir the bottle filled with a suspension sample and place it on rolls that rotate horizontally. In this research, the rotating rolls were driven by a recycled water pump electric motor which is transmitted using a pulley and belt. The research objective is to create a bottle roll machine that is practically easy and safe to carry out the leaching test or any other tests that involve agitation, especially for process engineering students. The performance validation of the equipment was done by conducting some leaching tests using the manufactured bottle roll to determine the consistency of the roll rotation, as leaching tests are generally done for a quite long period, usually 24 hours continuously. The sand sample was sieved into 100 mesh of particle size and then mixed with water to make a suspension. The suspensions were put into 2.5 liters of used glass chemical bottles and 1 liter HDPE plastic bottles with various diameters of 14 Cm, 12 Cm, and 8 Cm. The results showed that the machine could perform the leaching test at best in HDPE bottles with an average of 31 RPM of rotation speed tested for 24 hours.

Gold Adsorption from Pregnant Thiocyanate Solution Using Activated Carbon

Gold adsorption from dissolution of gold ore concentrate at Tanggamus mine using activated carbon from thiocyanate leached solution was investigated in this research. As the pollution of the environment has been raising accordingly with the increasing of cyanidation, thiocyanate is becoming current alternative and less toxic reagent in terms of gold dissolution. However, the research was still limited. The development and implementation of thiocyanate in gold extraction is the core of this research. Solvent and oxidizer concentrations (KSCN and FeCl3) were used in this study with 0.3 M and 0.1 M of concentration, respectively. Adsorption process was carried out for 4 hours using 100 ml of filtrate with activated carbon addition. Adsorption of thiocyanate complex gold compounds was studied by varying the size of activated carbon, the concentration of activated carbon, and the rotary speed of bottle roll. At-10+20# of activated carbon size, the %-adsorption obtained was 93.65%. Meanwhile, 94.31% of gold adsorption was achieved with the concentration of activated carbon at 1500 mg/l and 93.37% of gold adsorption was reached with the rotary speed of 150 rpm. Pseudo second order was applied to calculate the kinetics of gold adsorption with the R2 value obtained was 0.9999.

Mineralogical Characterization and Acid Pretreatment of a Gold Calcine Leach Residue

Miners around Zimbabwe used to supply gold concentrates from sulphide flotation to the Kwekwe Roasting Plant (Zimbabwe) for toll treatment. The concentrates were roasted in Edward’s roasters and the calcine product was leached by cyanidation. Due to inefficient roasting, overall gold recoveries of 75–80% left behind a rich calcine leach residue at the Kwekwe Roasting Plant. The characterization performed to establish a potential process route involved several techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), fire assaying and inductively coupled plasma (ICP). Assays conducted on samples from the 350,000 tons tailings dam residue, created over the operational years, gave an average Au grade of 8.58 g/t and 12.54 g/t for Ag. The base metals assayed—0.11% Cu, 0.10% Pb, 0.17% Zn and 26.05% Fe. SiO2 (36.1%), Fe2O3 (36.9%), Mg3Si4O10 (OH)2 (8.9%), NaAlSi3O8 (6.9%), and Fe3O4 (6.4%)—were the major mineral phases in the cyanide leach residue. SEM gold scans on 24 polished sections showed only 2 discrete gold particles of less than 5 µm, with one partially liberated and associated with quartz, while the other was fully liberated. Therefore, the particulate gold in the calcine leach residue was negligible. It was deduced from the analysis after ultrafine milling (P80 &lt; 5 µm) followed by cyanidation that 68.53% of the gold was sub-microscopic. Direct cyanidation using bottle roll resulted in only 2.33% of the total gold being leachable, indicating that the calcine leach residue was highly refractory. Diagnostic leaching by sequential use of acids in order of their strength resulted in HCl leachable phases (CaCO3, CaMg(CO3)2, PbS, Fe1-XS, and Fe2O3) freeing 4.2% of the total Au during subsequent cyanidation leach. H2SO4 leachable phases (Cu–Zn sulphides, labile FeS2) released an additional 26.57% during cyanidation, whereas HNO3 leachable phases (FeS2, FeAsS) released a further 20.98% of Au. After acid treatment and subsequent cyanidation, hot caustic leach of the residue followed by carbon in pulp resulted 4.43% of the total gold being eluted. Therefore, 4.43% of the total gold was surface bound. From the analysis after diagnostic acid leaching, it was deduced that a total of 54.08% of the gold was in the acid-leachable phase. Due to cost and environmental considerations, H2SO4 was selected for the evaluation of acid digestion as a pretreatment stage followed by cyanidation. Increasing the H2SO4 strength for the pretreatment of the calcine leach residue increased gold recoveries during cyanidation.

EFFECT OF PRESSURE ON GOLD CYANIDE LEACHING

Although the effect of high oxygen pressure on gold recoveries at elevated slurry temperatures was previously investigated, the sole effect of the pressure at ambient temperatures on cyanide leaching with the presence of nearly enough oxygen for the cyanide reactions to occur has not been found to be studied. This research work was carried out with the objective of investigating the effect of pressure on the recovery of gold from an oxide gold ore and flotation tailing (Carbon in leach (CIL) feed) samples during cyanide leaching process at room temperature. Pressure cyanidation experiments were run in a batch autoclave under different air and nitrogen gas pressures, and pH conditions. Atmospheric bottle roll leach tests for 24 and 8 hours resulted in 90.5% and 66.4% gold recoveries, respectively, whereas 8 hours batch autoclave leach tests under 90 psi air pressure resulted in 88.8% gold recovery from oxide ore samples. Flotation tailing samples leached under atmospheric and under 90 psi air pressure for 8 hours resulted in 16.8% and 34.5% gold recoveries, respectively.

Gold leaching from oxide ores in alkaline glycine solutions in the presence of permanganate

In this study, the effect of using strong oxidants with alkaline glycine solutions on the leach rate and recovery of gold was studied in the absence of cyanide. Prior research indicated that when using only alkaline glycine and air at ambient temperature in the absence of catalysts, leaching times would be too long for conventional agitated tank leaching of ores. The ores used in this study were from oxidised geological domains, which would not be expected to excessively consume oxidant. Ores with reactive sulfides or other reducing minerals would be expected to rapidly consume an oxidant, making the process ineffective. The influence of the oxidants such as potassium permanganate, hydrogen peroxide, sodium chlorate, potassium iodide, and potassium ferricyanide were initially evaluated in a screening test. The highest gold extractions were observed with potassium permanganate, where a recovery of 85.1% was achieved at 1.5 kg/t glycine and 3 kg/t permanganate at 30% solids, pH 10.5 and ambient temperature using a bottle roll process. This compared to a 87.4% recovery against a conventional cyanidation benchmark with 30% solids, pH 10.5 and ambient temperature using the bottle roll. Other oxidants only achieved a recovery of 11% at best, so permanganate was the focus of the optimisation work. The solution pH had very little effect on gold recovery between 9.5 and 11.5. The ratio of glycine to permanganate concentration is significant, if potassium permanganate is in a molar excess, the recovery is greatly reduced due to oxidation of the glycine. The main products of this reaction, when lime was used as pH modifier, were determined to be calcium carbonate, calcium oxalate, trace amounts of ammonia and manganese dioxide. Gold is recoverable from leach solutions by conventional adsorption onto activated carbon.

Increasing the heap leach efficiency of Uşak Kışladağ gold ore using nut shell as permeability aid

The objective of this study is to increase the gold recovery from the gold ore heaps of Uşak Kışladağ Gold Company adding nut shell as percolation enhancer. In the first step of this study, bottle roll experiments were carried out on the ore sample crushed below 18 mm, 10 mm, 2.36 mm and 74 μm. Gold recovery values obtained for bottle roll tests were 53%, 55%, 65% and 85% respectively for the particle sizes −18 mm, −10 mm, −2.36 mm and −74 μm respectively. The initial experiments provided information about the ultimate gold recovery that can be reached for the particle sizes studied. Following the bottle roll tests, column leach experiments were carried out for-18 mm (the original heap particle size) and −2.36 mm size fractions for a duration of 30 days. Gold recoveries of 48% and 40% were obtained for the size groups of −18 mm and −2.36 mm respectively. At the final stage of the study, the effect of nut shell addition on the gold recoveries was studied using column leach experimental set up. Test results showed that nut shell addition markedly increased the permeability of the ore and hence the leach efficiency. The increase in the finer particle size was more noticeable because of the increase in the permeability and decrease in the particle size. Gold recoveries for −2.36 mm particle size were 42%, 55% and 61% respectively when 2.5%, 5% and 10% nut shell by volume was added. Furthermore, no gold adsorption was observed on the organic substance.

Application and Selection of the Reagent to Neutralize Hydrogen Sulfide and Light Methyl-, Ethyl- Mercaptans in Oil

The choice of an effective neutralizer for a particular field is made on the basis of laboratory studies and pilot tests. A number of laboratory tests were conducted to select a hydrogen sulfide neutralizer for oil at the loading point of the Borodino field. The studies were carried out according to the standard method of the “bottle roll test” at 45°С with various amounts of the reagent-neutralizer by bubbling oil and reagents. Laboratory tests for the selection of effective reagents-neutralizers were carried out by modeling the process of collecting and preparing oil at the loading point of the Borodino field in two stages. The results of laboratory research allowed us to choose the most optimal neutralizer, set its flow rate, and temperature of oil heating. In addition, t influence of the place where the reagent - neutralizer is introduced into degassed oil is studied. The laboratory tests made it possible to select the best neutralizer Desoulfon-SNPCH-1200, to determine its minimum specific consumption and the temperature of heating oil. The application of this reagent-neutralizer will allow doing the effective oil preparation at the loading point of the Borodino field. The amount of Desoulfon-SNPCH-1200 needed to neutralize the mercaptans depends on their content in oil and the required degree of reduction.

The Efficiency of Amalgamation and Cyanidation for the Extraction of Placer Gold Deposits of Indus River Basin along Gilgit to Thalachi (Gilgit-Baltistan)

Separation of gold from placers are not given importance in Pakistan, but in the economy of Gilgit-Baltistan,it plays a vital role. The study mainly focused on shaking table technique for the extraction of gold from placer depositsalong Gilgit river between Gilgit and Thalachi, near Gilgit and Astore river junction. For the separation of gold, fromthe concentration of shaking table the Hg; mercury amalgamation has been used for it. In the result of theamalgamation process recovered gold was 27.12%. The cyanidation process was used to separate from remains ofmercury amalgamation, tailing and middling of shaking table. The graphical results of gold extraction with bottle rollcyanidation and agitation method were compared. The results of gold separation using bottle roll cyanidation andagitation methods were about 87.5% and 29.8% respectively. It is clear from the results, the bottle roll cyanidation is abetter technique for the separation of fine gold from placers along with downstream waterway areas, where placerdeposits occur.

The Efficiency of Amalgamation and Cyanidation for the Extraction of Placer Gold Deposits of Indus River Basin along Gilgit to Thalachi (Gilgit-Baltistan)

Separation of gold from placers are not given importance in Pakistan, but in the economy of Gilgit-Baltistan,it plays a vital role. The study mainly focused on shaking table technique for the extraction of gold from placer depositsalong Gilgit river between Gilgit and Thalachi, near Gilgit and Astore river junction. For the separation of gold, fromthe concentration of shaking table the Hg; mercury amalgamation has been used for it. In the result of theamalgamation process recovered gold was 27.12%. The cyanidation process was used to separate from remains ofmercury amalgamation, tailing and middling of shaking table. The graphical results of gold extraction with bottle rollcyanidation and agitation method were compared. The results of gold separation using bottle roll cyanidation andagitation methods were about 87.5% and 29.8% respectively. It is clear from the results, the bottle roll cyanidation is abetter technique for the separation of fine gold from placers along with downstream waterway areas, where placerdeposits occur.

Comparative Leaching Study on Conichalcite and Chalcopyrite Under Different Leaching Systems

Copper leaching from low-grade copper ore samples obtained from two active mines in the US, named conichalcite (sample A) and chalcopyrite (sample B), were studied under different leaching conditions using sulfuric acid and methane sulfonic acid (MSA). The conichalcite, sample A, is calcium-copper arsenite hydroxide [CaCu(AsO4)(OH)] with small amount of gold and other metals. The copper grade is 0.41% with 0.48% arsenic and 2.04% sulfur. The chalcopyrite, sample B, was the main mineral with 0.60% copper grade with 0.73% sulfur and 0.032% molybdenum. Leaching systems utilized two oxidants (ferric ion and hydrogen peroxide) to investigate the kinetics of copper extractions. All leaching tests were performed by bottle roll leaching tests with 6.25% pulp density for 24 hours. Results showed that the leaching kinetics were relatively fast for oxidized sample A. Overall copper recovery was slightly affected by the oxidants and higher than 60% copper extraction was observed. Screen fractioned materials and the leached residue analysis showed that the copper grade in the residues are relatively consistent with 0.14-0.16% copper. This results showed that the ore samples contains readily leachable copper and refractory elements in all size fractions. The refractory portion seems to be relative uniform with wide range of easily leachable copper with 0.30 to 0.54%. Copper extraction from sample B using acids with ferric ion as an oxidant showed around 35% but it significantly increased over 80% using hydrogen peroxide as an oxidant. The copper extraction gradually increased up to 3.0 mol/L hydrogen peroxide content. (Received December 6, 2018; Accepted January 31, 2019)

Improving the gold leaching process of refractory ores using the Jetleach reactor

Gold ores have been a subject of numerous investigations aimed at enhancing gold recovery and improving leaching kinetics. This is because the cyanidation process cycle, although well established and well researched, remains a process of long duration. To reach the acceptable gold recoveries i.e., +80%, some ores are leached for 24 h, or more, depending on the type of ore. Faster kinetics would help in lowering the processing cost.This work examines the development and application of the Jetleach reactor, as a device for improving the leaching kinetics of gold ores. The Jetleach reactor is designed to propagate micro-cavitation by impacting two pulp streams against one another at a relatively high velocity, through a pair of coaxially aligned nozzles in a chamber filled with oxygen under pressure.When applied to free milling ores, the Jetleach reactor has been shown to improve the gold recovery by almost 10% after only 2 h. The Jetleach has the potential to considerably reduce the leaching time required in cyanidation processes.In experiments the Jetleach was applied to refractory gold ores including Diorites (DIO) and Meta-volcanic Ore (MVO) ores from West Africa. The reactor has shown improvements in gold recoveries when compared to the conventional stirred tank and bottle roll leaching methods. On the DIO sample, the Jetleach reactor was able to improve the gold recovery by almost 8% and 10% respectively compared to the conventional and bottle roll method; while the improvement was about 10% and 15% on the MVO samples.Pilot plant test-work, on Witwatersrand gold plant tailings has suggested improvement in recoveries of some 10% with concomitant reduction in reagent consumption.This suggests that the employment of such reactor in a cyanidation process for the treatment of refractory ores could provide economic benefits.

Mineralogical Characterization and Determination of Refractoriness of Malaysian Gold Ore

This study aims to conduct mineralogical characterization and determine the refractoriness of gold ore from Eastern Coast of Peninsular Malaysia. Elements presence in the sample were investigated using X-ray fluorescence (XRF) analysis while X-ray diffraction (XRD) method was used for the identification of mineral phases. Polished sections samples were studied by optical microscopy (OM), scanning electron microscopy and energy-dispersive X-ray (SEM/EDX). XRD phase analysis showed the presence of mineral phases of quartz, iron sulphide and silicate minerals, which were confirmed by XRF with the elements detected as Si, O, Al, Fe, As and S. From SEM/EDX analysis, gold was found mostly interlocked in sulphide minerals such as arsenopyrite, galena and others. Fire assay and cyanide bottle roll test were employed on the bulk samples to assay the gold content and free gold, respectively. Atomic Absorption Spectrometry (AAS) revealed the gold content to be 31 gram per tonne in the sample. The cyanide bottle roll test determined the free gold assay of 16 gram per tonne. These findings imply that the samples contained free gold of about 52% along with gold present interlocked with minerals unfavourable to cyanidation, which further provide valuable information in terms of the refractoriness of the gold for further processing.

Feasibility of electrokinetic in situ leaching of gold

Conventional gold mining operations are facing significant challenges due to declining ore grades and increasingly higher strip ratios. To meet global demands while limiting associated environmental impacts, alternative techniques to extract resources, including gold, are urgently needed. We suggest that in situ leaching coupled with electrokinetics (EK-ISL) could potentially enable recovery of gold from (subeconomic) ores with a significantly smaller environmental footprint than current mining techniques. EK-ISL would involve the leaching of gold, in situ, using a lixiviant that is introduced via a set of wells. A voltage gradient is applied to transport the lixiviant through the orebody. The gold is leached and also transported towards a set of recovery wells. At the surface the gold is recovered and the lixiviant can be recycled.This study was designed to verify the in-principle feasibility of this novel technique. A series of laboratory experiments was performed with an iodide/tri-iodide solution as lixiviant to extract gold from unconsolidated porous media. Experiments in which pyrite was included as proxy gangue mineral and complimentary bottle roll tests showed a declining efficiency of EK-ISL gold leaching with increasing pyrite oxidation. However, 80% gold recovery was still achieved, even with the highest tested pyrite concentration (5.26wt%). The coupled transport and reaction processes were interpreted and quantified through numerical model simulations that were constrained by the experimental observations. Overall the experimental and numerical modeling results suggest the in-principle feasibility of EK-ISL.

Investigation of Affecting Parameters on Heap Leaching Performance and Reducing Acid Consumption of Low Grade Oxide-Sulfide Copper Ore

Heap leaching method is known as cheap method for copper extraction. Presence of clay and acid consumer waste minerals are the most critical issues because they may bring out the process from economic mode. For reduce acid consumption and increasing copper extraction in heap leaching method, about 3 tons sample was taken randomly from different low grade zones. After homogenization and spelling into small parts, bottle roll tests were carried out to achieve maximum copper recovery and acid consumption in a short time at pH= 1, 1.1 and 1.2. Maximum copper recovery were 60.8, 60.2 and 60.1%, respectively. Also acid consumption were 107.30, 99.90 and 93.23 kg/t of ore, respectively. After diagnostic tests, nine columns with dimension 2m height and 15cm diameter were filled by 0.5, 1 and 1.5 inches ore. Columns were irrigated with 7, 9 and 11 g/l as acid solution concentration at flow rates of 7, 11 and 15 l/m2*h for 63 days. Results showed that there are high correlation between copper and iron recoveries. Copper recovery changed from 25.5% to 58.9% while iron recovery changed from 4.7% to 15.2%. Acid consumption were achieved between 18 to 54 kg per ton of ore. Acid solution concentration and irrigation flow rate are the most important parameters on the copper and iron recoveries. By increasing of leaching period Copper extraction will increase, but acid will be waste more. Copper and iron recoveries were increased with increasing the acid solution concentration and irrigation flow rate but Increasing in amount of acid consumption does not increase copper extraction inevitably. Irrigation flow rate of acid solution has significant effect on acid consumption. With decreasing the ore particle size, both of copper recovery and acid consumption were increased.

LIXIVIAÇÃO DE MINÉRIOS DE OURO DE BAIXO TEOR POR ROTA ALTERNATIVA AO PROCESSO DE TANQUES AGITADOS (CIL)

Avaliou-se no presente trabalho uma rota alternativa para a lixiviação de minérios de ouro de baixo teor para se integrar a uma planta industrial no Uruguai que atualmente emprega o processo Carbon in Leaching (CIL). Diversos ensaios de lixiviação utilizando-se a técnica bottle roll test de 20 litros e colunas de 3 metros foram realizados visando-se estabelecer alguns parâmetros, critérios de operação e dimensionamento para avaliar um processo industrial de lixiviação para tratar cerca de 1.000.000 de toneladas de minério contendo cerca de 0,65 g de ouro por tonelada de minério (g/t). Foram concebidas pilhas de 4 metros de altura, minérios com uma granulometria 80% menor que 12,67 mm (P80 de 12,76mm), tempo de operação de 3 anos e atingindo-se uma produção anual de 455 quilogramas de ouro.doi: https://doi.org/10.18540/2446941602022016029

Estimating process design gold extraction, leach residence time and cyanide consumption for high cyanide-consuming gold ore

Plant design parameters for gold extraction, leach residence time and cyanide consumption are generally determined from standard bench-scale bottle roll or agitation leach tests. The application of laboratory data to process design has essentially evolved from the testing of oxide or low cyanide-consuming ores. Such scale-up factors may not be appropriate for ores that deplete cyanide and oxygen since this interferes with gold extraction kinetics. High cyanide-consuming ores also exacerbate the differences between the conditions applicable to small batch tests and large continuous operations. Testing a reactive high-sulfide South American ore deposit necessitated the re-evaluation of conventional bench-scale cyanidation procedures. Pulp density can be a major factor affecting the results for plant design purposes and should be treated as a test work variable. As with high clay-bearing ore, where pulp viscosity can hinder mass transfer, minimizing the influence of test equipment on gold extraction kinetics may require low pulp densities. This introduces interpretative complexity since cyanide consumption changes as a function of pulp density. Activated carbon also consumes cyanide, so its effect has to be accounted for in the case of carbon-in-leach (CIL) or carbon-in-pulp (CIP) plant flowsheets. Since cyanide is an expensive reagent, often a major component of plant operating costs, it is important that the scale-up of cyanide consumption from laboratory to plant be representative. The traditional method of reporting cyanide consumption in bench-scale testing is questioned since it takes credit for residual free cyanide in leach tails. The projected plant consumption may be better estimated by using the total cyanide addition in a laboratory test. We propose a test work protocol that categorizes the cyanide consumption into its components but requires more extensive testing to generate design data. The ultimate validation of scale-up factors used by project engineers requires rigorous bench-scale versus commercial plant comparative data. Such data are not readily available.