Strong sulfuric acid was applied as a cure followed by leach solution application over a cycle time that varied between 45 to days depending on the soluble copper content of the ore. The SX plant was built with four parallel trains each having three extraction and two stripping mixer-settlers.
The design was typical first generation with single-stage round mixers and long, rectangular settlers. The copper-loaded electrolyte from the SX flowed by gravity to one of three electrolyte tanks at the EW tankhouse. Make-up water, acid and cobalt additions were done in the weak electrolyte tank. The system operated at ambient temperature without the use of heat exchangers.
The EW tankhouse was built with three separate cell sections; one starter sheet section and two commercial sections, Block A and Block B. Within each section the cells were connected in parallel hydraulically and in series electrically. The general layout of the original tankhouse is shown in Figure 1. The individual cells in each section were fed from branch lines coming off a main manifold.
The electrolyte entered the cells through a vertical bored pipe with a butterfly valve at the top for flow control. The cells were constructed with reinforced concrete and lined with paraliner lining and acrylic sheeting as bumper boards. The cells were placed on glass insulators for electrical insulation and supported on columns 1.
The three cell sections each represented a separate electrical power block equipped with a transformer and rectifier for converting alternating current to direct current. The commercial sections each had two rows with 52 cells per row for a total of cells per power block.
The electrode spacing in the cells was set at The starter sheet blanks were of stainless steel design, L, and harvested daily to produce 1. At the time cathode production had fallen to a level of 18, mtpy about half the nominal EW design capacity. Since initiating operations the cathode quality had been reasonably good and the facilities were well maintained.
Project design and engineering was contracted to Fluor Daniel Wright of Canada. The evaluation of the existing tankhouse design identified areas for incorporating EW process improvements that had become accepted practices in the industry in the twenty years since the Cerro Verde start-up. A trade-off study was performed between continued use of starter sheets and conversion to permanent cathode blanks.
However, results of the study indicated manpower reductions did not justify the capital required for such a conversion and the decision was made to continue with the existing copper starter sheets using 7 to 8 day harvest cycles. The electrolyte flow between the SX and EW incorporated a system of dual-media filtration to reduce organic entrainments and solids.
The operating parameters for rich electrolyte copper tenor were increased to 47 grams per liter gpl and 35 gpl for the lean electrolyte to ensure sufficient copper concentration in the cells to maintain starter sheet and cathode quality. The electrolyte bleed system capacity was increased to assure the 1. In addition, a new water purification plant was installed for make-up water supply. An electrolyte heating system was installed consisting of a new fuel oil boiler and four plate and frame heat exchangers.
Rich electrolyte from the SX first passes through two heat exchangers in series and countercurrent to the lean electrolyte. The other two exchangers operating in parallel using hot water from the boiler heat the slightly warmed electrolyte to the final temperature.
The capacity of the commercial Power Block A and Power Block B needed to increase to deliver the higher amperage required. A new 30, amperes transformer rectifier was installed on Block B. The 20, amperes units removed from Block B were installed in parallel with the existing units on Block A to give that side an installed capacity of 40, amperes.
Some minor changes were required in the main bus bars to the power blocks but the inter-cell bus bars and cathode hanger bars were properly sized for the increased current. A cathode press was installed to ensure the starter sheets hang down straight and parallel to the anode. This proved to be a critical process improvement considering the conversion to rigid permanent blanks was not deemed economical. The starter sheets were removed and pressed 36 hours after initial placement in the cells.
The pressing operation has an important impact on current density and quality in a starter sheet operation. A new Wenmec starter sheet assembler was installed to replace the manual loop punch. The machine rigidized the sheets and attaches them to the hanger bars with copper loops. This increased the safety, speed and productivity of the starter sheet operation and also improved sheet performance in the cell until presses by the cathode press. Operating at the higher current densities required changing the crane pull rack to avoid subjecting cathodes in the cell to peak densities during pressing or harvesting.
The original rack pulled half a cell, 23 cathodes, at a time. A new pull scheme to pull the cell by thirds was adopted with a new rack design. Process changes in the crusher and leaching areas resulted in higher than expected metallurgical performance and Cerro Verde sought to increase plating capacity even more. Further changes were pursued through process optimizations to fully utilize the installed rectification capacity. For how long have you been using it?
Since August Did you try many other models before getting this one? Many other model in the genre, but mainly lower-end manufacturer wharfeadale; Behringer What is so special that you like best? I amplifies them with a QSC GX5 in full range as a floor, with w per speaker ca snoring already very good, the bass is punchy and the highs are clear and powerful!
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