LEACHING OF A ROASTED COPPER SULFIDE ORE Rosselle Kim P. Castillano, Wilfredo T. Gatdula Gatdula Jr., Gin Derick L. Magno, Jhunalyn Jhunalyn H. Parantar METE 157N: HYDROMETALLURGY LABORTORY
ABSTRACT Sulphide ores of copper are insoluble in dilute sulphuric acid leaching solutions, but a very high extraction can be obtained if the copper ore is in the oxidized condition. The problem is to convert the sulphide into the oxide form. This can be done by giving the sulphide ore an oxidizing-sulphatizing roast. Copper sulphate is soluble in water, so acid will be saved in the leaching process if copper sulphate is present. From assays of the pregnant liquor t he percentage extract ions o f the copper present in the calcine were calculated. The copper present in the roasted calcines were also determined to examine the efficiency of leaching in extracting t he copper.
INTRODUCTION In the last three decades, the economic conditions and the increasingly stringent environmental legislation worldwide have led metallurgical industry more difficult to develop. In addition, copper resources become increasingly depleted and the number of low-grade refractory copper ore grows day after day. Therefore, more att ention must be paid to develop a low-cost, environment-friendly environment-friendly and high economic benefits process of recovering copper from ore. The extraction of copper from ore has commonly been performed using mainly pyrometallurgical, hydrometallurgical and biochemical, and metallurgy equipment always suffered serious erosion, leading to high production cost. Biochemical processes are mostly popular in processing the low-grade tailings or abandoned ore. While the use of this process is restricted by the strict growth environment such as temperature, pH, oxygen concentrate and light condition of microorganism and the long leaching period. However, hydrometallurgical process does not have the problems mentioned before. Therefore, hydrometallurgical process becomes the most viable and promising approach to treat copper sulfide ore in metallurgy fields. In hydrometallurgical process, the most widely used pretreatment process is roasting before leaching. There are three common roasting methods: oxidation roasting, chlorination roasting and roasting. Oxidation roasting needs high roasting temperature and copper will suffer a loss by generating copper ferrite. The exhaust gas (SO2, Cl2, HCl) from the furnace in chlorination roasting process is a threat to the environment. In roasting, copper was mainly formed to soluble sulfate by water or dilute acid after roasting. Mostly this method is applied to pretreatment of copper concentrate with high percentage of sulfur. A sulfate promoter can change t he roasting roast ing atmosphere from oxidation to reduction, with releasing sulfur dioxide, turning metal oxides and sulfides to soluble metal sulfate. Pyrite, sulfur, and sulfuric acid are the sulfate promoters normally used to produce the reductive atmosphere. Prasad and Pandey studied
the roasting of the mixture of copper-iron sulfides and copper sulfide formed copper sulfate, whereas iron sulfide converted mostly to hematite at 500˚C. In the present work, a roasting-acid leaching process that associated pyrometallurgical and hydrometallurgical methods has been used for the recovery of copper from a copper sulfide concentrate. The reactions investigated show an enhanced recovery of copper from its concentrate into a leachate which is almost devoid of iron. Suitable roasting temperatures, roasting time and a proper amount amount of addition have have been explored in this study.
OBJECTIVES OF THE STUDY The experiment aims to study the various extent of leaching the roasted copper ore and apply cementation and titration method in the resulting pregnant solution.
SIGNIFICANCE OF THE STUDY In this experiment the application of cementation method will determine its efficiency in the extraction of copper.
MATERIALS AND METHODS The materials used were stirring rod, hot plate, 1000 mL beaker, 250 mL beaker, sulfuric acid, filter paper, filter funnel and aluminum scrap. The copper sulfide ore was roasted at 900 degrees C for one hour. The total copper (% CuO and CuSO 4) was determined through the analysis of copper and sulfur. Sulfur was determined gravimetrically as barium sulfate and copper was determined volumetrically by titrating with standardized KCN solution after iron was removed by precipitation with NH4OH as iron hydroxide and by filtration. After the titration of the filtrate, the end point gave a
Leaching of a Roasted Copper Sulfide Ore. Submitted to Engr. Alma Mae Batucan, Instructor. Page 1 of 2
clear solution. A solution consisting of 6 % sulfuric acid added with roasted calcine and water in a 1000 mL beaker was then prepared for leaching. The leaching process was done by stirring for one hour and the resulting solution was filtered. In the cementation process, the filtered leach solution was added with aluminum scraps, heated to near boiling point temperature and was associated with constant stirring until the solution has cleared. Filtration of the cement copper was t hen obtained and aluminum scraps were collected. After dr ying, both the cement copper and aluminum scraps were then weighed.
copper. However, in the titration part, the blue solution did not give a clear solution at some time that is why the end point and the %Cu was not obtained. At table 2 below, the data for the preparation for leaching is place and titration data is excluded because of the said outcome. Table 2. Data for Leaching %solids 15% solids Sulfuric Acid 10 ml Volume of Water 190 ml Amount of Coal 40.65 g The leached product using the data above was filtered. After the ore has been roasted and leached, the resulting solution was transferred to the beaker, where cementation was performed. The data is shown below in table 3. Table 3. Data for Cementation Before After 25 ml 1.49 g 1.35 g 0.14 g
Volume of Solution Amount of Aluminum Strips Amount of Copper
In accordance with the above data, the copper which resulted from cementation is very low. And it was observed that there were white particles and we speculated that it accumulated because the strips were not properly washed after the cementation stage.
Figure 1. Flowsheet
CONCLUSION AND RECOMMENDATION
RESULTS AND DISCUSSION
We conclude that the roasted or e has certain amount of copper that can be extracted through leaching and filtration.
Table 1. Data for the Roasting Stage Weight of Sample + Crucible Weight of sample After Roasting Weight of sample after roasting
Trial 1 53.25g 30.00g 43.35g 20.10g
Trial 2 53.16g 30.00g 43.23g 20.07g
As shown in the table above, after roasting the copper sulfide ores, the weight of the ore is notice to have reduced. The weight reduced because the roast converted a considerable portion of the copper to t he oxide form and a lesser amount to the form of sulphate, and all of the iron to ferric oxide if any existed. Also, the decomposition temperature of copper sulphate is 650 degrees Centrigrade, so that theoretically the correct temperature of roasting should exist in 650. By roasting at 900 degrees Centrigrade, a maximum amount of copper oxide and of copper sulphate should be obtained. After roasting, the ore was leached and some portions were titrated for the determination of
Hence, during roasting the copper extracted is mainly affected by temperature and time. It is recommended that this experiment requires a skilled person to perform this one, for it is very crucial and needs a lot of reminders to be considered. In addition, one must know its use and relevance to be able to appreciate the experiment and can produce an accurate results.
REFERENCES Zhao, Yaming, et.al. Recovery of Copper from Copper S ulfide Concentrate by Sulfation Roasting . Scientific Research Publishing Inc. February 2015. “
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Tumen, F. and Bailey, N.T. (1990) Recovery of Metals from Copper Smelter Slags by Roasting with Pyrite. Hydrometallurgy, 25, 317-328.
Leaching of a Roasted Copper Sulfide Ore. Submitted to Engr. Alma Mae Batucan, Instructor. Page 2 of 2
Leaching of a Roasted Copper Sulfide Ore. Submitted to Engr. Alma Mae Batucan, Instructor. Page 3 of 2
