Dewatering Reduces Costs at Angas

Start-up at Terramin Australia Pty. Ltd.’s Angas mine in Australia has exceeded expectations thanks to higher than expected grades of zinc and lead ore. As a result, full rate production at the new lead-zinc mine was brought forward by six months to January 2009.   Aided by a lean start-up and lower consumable costs for grinding, milling reagents, diesel, as well as lower costs for smelting and shipping, the mine’s site operating cash costs for 2009 have now been revised downwards, despite a weaker Australian dollar. The concentrator is using the latest peristaltic pumps and Ceramec filters from Larox for concentrate dewatering to produce filter cake ready for transport.

Terramin Australia developed the Angas mine because of its high-grade ore, proximity to infrastructure such as ports, roads, water and power, and the potential for expansion. Terramin has a whole-of-mine offtake agreement with Sempra Metals and Concentrates Corp. for the Angas concentrate. Ore throughput is expected to yield 400,000 mt/y of concentrates for the life of mine, forecast to contain an average 60,000 mt/y of zinc and 22,000 mt/y of lead. The South Australian Center for Economic Studies predicts that Angas’s initial seven-year mine life and future expansion possibilities will boost the local economy by A$29 million per annum.

Situated just 60 km from Adelaide and exploiting a resource of 2.4 million mt, Angas was commissioned on July 18, 2008, and produced nearly 23,000 mt of high-grade lead and zinc concentrate by the end of its second quarter. Lead concentrate is being trucked to the Port Pirie smelter while zinc concentrate is delivered to Port Adelaide before shipping to Korea.

Stringent mine and rehabilitation plan conditions for Angas are helping to reduce the potential environmental impact on Strathalbyn, a nearby local development. Noise levels cannot exceed 47 dB by day or 40 dB by night. Groundwater contamination is minimized by the containment of process waste in a state-of-the-art tailings storage facility, valued at A$7.5 million, which is double-lined with high-density polyethylene (HDPE) and sized for mine expansion.

Dewatering with Ceramec
The mine’s start-up progress, which has far exceeded Terramin’s expectations, is due in part to the high performance of the filtering and drying system for the two concentrates, according to Larox Corp., which supplied and services the system. The installation comprises two Ceramec filters, fed by two peristaltic roller compressing pumps. The extracted filtrates are very high in clarity while the dried filter cakes meet required transport moisture limits (TMLs) for their ore grades.

Angas’s general manager, John Burgess, initially planned to install Larox pressure filters rather than Ceramec filters as he had experienced optimization issues with an earlier version of Ceramec filters at Broken Hill in 1985. However, extensive tests and other site successes convinced him that the latest Ceramec filter would be ideal for Angas.

The feed pumps employ a single, bearing-mounted roller design that compresses each hose once during a 360° operating cycle. This feature reduces the hose compressions required by 50% when compared with traditional peristaltic pumps that use two sliding shoes, according to Larox.

The pumps feed the thickened, relatively coarse lead (P80, 50 μm) and zinc (P80, 71 μm) concentrates into their respective filtering system, where concentrates coat the ceramic disk segments during immersion into slurry baths and dewatering starts immediately via capillary action. Extracted filtrate passes through microporous holes in each disk before being transferred away by a small 2.2-kW vacuum pump. The dried filter cake that remains is continuously scraped off as the disks rotate.

Burgess selected a Ceramec model CC30 disc filter (30-m² filter area) for the zinc and model CC6/15 (6-m² filter area expandable to 15 m²) for the lead. The latest Ceramec filter, with new ultrasonic positioning between the disks, is operating at Angas at rates of 75% to 90% over a 24-hour period, depending on the ore grade being received.

When lead ore head grades were found to be higher than expected soon after installation, Larox suggested to Angas that a filter upgrade from the CC6/15 to a CC9/15 would provide the most economic expansion option. The extra disk, now installed, is providing Angas with a 30% increase in filtration capacity. As a result, the lead filter can capably handle higher lead head grade and increase production while still producing filter cake under the required TML.

Commenting that Angas is professionally set out and producing on its investment because things are done right, Burgess said he is nevertheless “pleasantly surprised” at the performance of the dewatering system. And the Algerian government is now interested in what Angas mine is doing for Terramin’s development of its large Tala Hamza zinc deposit in Algeria.

Larox commented that the benefits of using Ceramec filters and Larox peristaltic pumps being realized at the Angas mine, as well as at other sites, include: a plug-and-play design; no downturn is required for maintaining filter disks; only once-a-month maintenance checks are needed for filter ultrasonics and seals; routine filter backwashing is automatic and takes only half an hour per shift; feed pump hose leaks can be easily detected; revolution counters can record pump hose life (thereby reducing unscheduled stoppages); and processing noise levels can be kept to a minimum.

Larox is providing Angas with full support from its new South Australian office for filter and pump aftermarket service agreements. This enabled the quick replacement of a defective generator unit in the ultrasonics of one of the filters while it was still under warranty. Larox says it actively responds to any performance queries with its customers directly.

Larox has developed its organization from two offices in Sydney and Perth to a network of seven offices that are located near to its customers in Australia. Larox’s Australian service team has grown in the last 12 months from 6 persons to 28 persons. Larox now has service offices in Kalgoorlie, Perth, Tasmania and Adelaide and said this national distribution will help reduce the lead times on spare parts.

Meanwhile, new orders to supply filters to mining, metallurgical and chemical industry applications have been received from Asia, Australia, Europe, North America and South Africa. The total value of the deals is approximately €5.8 million ($7.7 million). The deliveries, to take place in 2009, consist of Larox automatic pressure filters, Hoesch horizontal membrane filter presses, Pannevis horizontal vacuum belt filters, and Ceramec capillary action disc filters. The mining and metallurgical applications are in nickel, copper and gold concentrate and ferrochrome filtration.

High Pressure Pinch Valves Handle Silver Tailings

South African pinch valve specialist Corflex Engineering has supplied 12 high-pressure valves, each with a working pressure of 72 bar, for a silver mine in Bolivia, South America. The company believes this to be the highest pressure that a 200-mm pinch valve has ever been built for. The order, worth over R2 million ($238,000), is for valves to operate at a tailings dam where the pipeline pressure is supplied by positive displacement pumps.

Because of the high operating pressure the valves had to be hydraulically operated. And as there is no electrical power available at the tailings dam, each valve was fitted with its own hydraulic power pack and designed to be operated from a mobile generating set. The order was a new development for this size of high-pressure pinch valve, taking over seven months to produce.

To close and seal 200-mm (8 in.) pinch valves at 72 bar (1,044 psi) requires a minimum force of 44 mt plus a good safety factor, so a special valve body had to be designed and built. The valve body is fitted with two opposed non-rising hydraulic cylinders securely bolted to the body, with large-diameter high-tensile cap screws. Most types of pinch valves are built with rising actuators, which is generally the least expensive way of building pinch valves. However, for this order, the more expensive and stronger non-rising pincher actuation, where the pinchers move independently from both sides, had to be used. The two body halves are also securely bolted together using high-tensile bolts. Because of the high pressure involved, the valves are very heavily constructed. The finished product weighed over 1,600 kg (1.6 mt). The valve bodies are designed to contain the sleeve test pressure in the event of a sleeve failure.

Open-frame pinch valves in high-pressure applications are potentially dangerous in the event of a sudden pinch valve sleeve failure, which is similar to a burst pipe. Corflex safety requirements only recommend enclosed pinch valves which are able to withstand the pinch valve sleeve test pressure, for all high-pressure applications.

The 200-mm pinch valve sleeves have a design working pressure of 75 bar (1,088 psi). The rubber hose sleeves have a test pressure of 150 bar, which is twice the highest recommended working pressure and allows for a good safety margin. Corflex had to design and build special tooling to build these sleeves, as well as a test rig to test them. The pinch valve sleeves were built by Dunlop Industrial Products, which has been building all Corflex pinch valve sleeves at their factory in South Africa since 1984. These high-pressure sleeves and all other Corflex pinch valve sleeves are built to the highest standard required by Dunlop’s strict ISO 9001:2008 quality assurance program.

This order enabled Corflex, which supplies pinch valves for both low- and high-pressure applications, to increase its size range for very high-pressure pinch valves. The development of high pressure pinch valves means that they can now be used in applications where previously only steel valves were used, often requiring frequent downtime and expensive maintenance.

Outotec Tests and Proves TankCell-300 at Chuquicamata…

Finland-based Outotec recently announced the completion of a joint testing program with the TankCell-300, at Codelco’s Chuquicamata Division in Chile. This follows the installation last year of three of these cells, which are the world’s largest mechanical flotation cells with an active volume of over 300 m3, at OceanaGold’s Macraes operation in New Zealand.

During the program the new cell was tested against the plant’s existing TankCell-160 units, with an active volume of over 160 m3, which Outotec had installed in 2001. Results were obtained during normal operation of the plant, where feed rate to the cells was 3,600 dry mt/h on average, with a coarseness (P80) of 300 µm and copper content of 0.6%. Process sampling was carried out twice a day, averaging four hours per campaign.

In its initial setup, the single TankCell-300 was measured to be 3.7% units higher on recovery compared with the two TankCell-160 machines in the parallel bank, while reaching an equal grade of copper in concentrate (averaging 20.0%). In this setup, the TankCell-300 consumed 205 kW of energy, when adding the consumption of the cell mechanism and the blower together. Thus the specific energy consumption of the cell was 0.66 kW/m3. The same measurement in the TankCell-160 yielded a result of 0.71 kW/m3.

An alternate hydrodynamic setup of the TankCell-300 was also trialled in a continuation of the testing program. During this period, the cells were fed with lower-grade ore (0.49% copper). This setup of the TankCell-300 further improved the metallurgical results, with over 5% units higher recovery and 1% unit better concentrate grade than in the parallel two TankCell-160 cells. Also the energy consumption was lower at 0.58 kW/m3 (specific) for the TankCell-300.

The larger TankCell did not exhibit sanding or mechanical problems throughout the entire testing program. The cell has subsequently been incorporated into the flotation circuit at Codelco’s Norte Division.

…..wins service contracts in Chile and Canada

Another strong feature of Outotec’s performance in 2008 was the rapid development of the company’s service business, which grew by 75% relative to 2007. Outotec has an installed base of over 2,000 deliveries worldwide, many of them requiring different services on a continuous basis. To increase its ability to provide such services Outotec acquired Canada-based Auburn in 2008 and has subsequently won several service contracts for industrial and maintenance services in Chile and Canada. The total value of these services is approximately €15 million ($20 million).

The orders include: industrial services for Codelco’s Minera Gaby copper mine in northern Chile, including maintenance and cleaning services for five years; maintenance and cleaning services for Xstrata’s Altonorte smelter and sulphuric acid plant in northern Chile for three years; and smelting furnace rebuild services for Vale Inco’s nickel smelter located in Sudbury, Canada. The services will be provided by Outotec Auburn.

According to Tapani Järvinen, outgoing CEO of Outotec, “We have invested strongly in the development of the Services business. These contracts demonstrate that our work is bearing fruit. Outotec Auburn has a strong presence in Canada and Chile, but with Outotec’s large network of sales and service centers the unit has good opportunities to grow its business globally”.

Bateman Gets Around

While Bateman Engineering still does a lot of business in southern Africa, for instance recently delivering converters to the Ambatovy nickel project in Madagascar, the scope of the company’s activities continues to widen partly as a result of international acquisitions.

In Western Australia, Karara Mining Ltd. awarded Bateman an A$12 million (US$9.1 million) contract to carry out front-end engineering design (FEED) for its Karara iron ore project. This project is a substantial integrated iron ore project, which will produce some 11 million mt/year of magnetite concentrate from 2010. Karara Mining is a joint venture established between Western Australia-based iron ore producer Gindalbie Metals Ltd., and Ansteel, the second largest steel maker in mainland China, for the development and operation of the project.

Bateman’s contract, awarded in September 2008, runs through to April 2009 with an additional arrangement for technical support to be provided through to November 2010. The FEED package involves the provision of a magnetite ore processing plant, designed with a modular construction, which will have a capacity of 20 million mt/y with built-in capability to be expanded to 40 million mt/y. The company stated that the award of this contract is due in part to Bateman Engineering’s demonstrated experience in this field and that of its subsidiary Metplant Engineering Services in upgrading a crushing plant for OneSteel Manufacturing in Whyalla, South Australia. Completed in 2007, this EPCM contract covered new primary, secondary and tertiary crushers, ore conveying, storage and stacking, sampling systems, process control design, electrical design and infrastructure to produce 9.6Mmt/y of iron ore product in two forms. The first was direct-shipping hematite lump and the second was magnetite feed to the downstream concentrator.

At the Sukari Gold Mine in Egypt, Bateman is nearing completion of a $6-million, cost-reimbursable contract for the engineering design of a 4-million-mt/y gold processing plant intended to yield 200,000 oz/y gold over a 15-year mine life. The mine is situated about 700 km south of Cairo and 25 km west of the Red Sea port of Marsa Alam, on the site of ancient gold workings by the Egyptians and Romans in the Eastern Desert of Egypt. Development followed the completion of a definitive feasibility study and Sukari is the first modern era gold-mine operation in Egypt. Bateman’s contract is being carried out for Pharaoh Gold Mines NL, a subsidiary of the Western Australian-based Centamin Egypt Ltd.

Started in July 2007, the project came into the Bateman Engineering Group fold following the group’s acquisition of Metplant Engineering Services Pty Ltd in 2007. Metplant, which now operates as part of Bateman Engineering’s Australia and South East Asia business unit, has a strong track record in the design and engineering of gold process plants and the firm’s involvement in the Chirano project in Ghana was one of the drivers for Centamin selecting them for this project. The project covered the processing design for both an oxide and a sulphide treatment circuit. These required the full spectrum of facilities for the flotation and regrinding of the sulphides plus conventional carbon-in-leach (CIL) for the oxides.

Much of the work concerned the refurbishment of an existing CIL process plant purchased by Centamin from the Kori Kollo mine in Bolivia, where it had been built and commissioned in 1993 and had operated for 10 years. A special feature of the newly refurbished plant is the incorporation of a Stirred Media Detritor (SMD) fine grinding circuit which enables gold recovery via conventional CIL.

Bateman Engineered Technologies (BET), a strategic business unit of the Bateman Engineering Group, has opened an office in Calgary, Canada to spearhead business development, initially in North America. The office will market Bateman Engineered Technologies expertise and technologies in bulk materials handling, as well as its range of specialised processing equipment. Delkor, which was acquired by Bateman Engineered Technologies in 2008, will continue to market its processing equipment in Canada from its operation in Vancouver. Bateman Engineered Technologies already has a sound track record in North America, with a current involvement in the US$14 million Windfall project, a significant bulk materials handling project in Western Canada.

On the specialized equipment side, the division has supplied four pneumo-drier systems for Canadian projects, two of the most recent being for major De Beers diamond projects: the Snap Lake and Victor Mine Recovery Projects. Bateman Engineered Technologies also supplied a vacuum spillage and transport system at Snap Lake for the same project.