Producers Show Interest in Integrated Iron Ore Washing and Water Recycling Systems
March 2011 | Operating Strategies
CDE Global, an Ireland-based supplier of systems and services for sand washing, lignite removal, construction/demolition waste recycling and waste water treatment, reports an upturn in interest among its aggregate clients for water recycling capabilities in aggregate wash plant operations. It's a trend the company hopes will spill over into its burgeoning business supplying plants to wash contaminants from iron ore.
In the aggregates production sector, said Marketing and Sales Support Manager Peter Craven, "as recently as three or four years ago a thickener or filter press was only specified on around 20% of our washing plant installations. The last 12 months has seen this figure rise to around 80%."
According to Cravens, the key drivers behind the increased interest in this equipment differ from one installation to the next but generally involve concerns about space available on site to accommodate large settling ponds, availability of the volumes of water required to operate a new washing plant, reducing health and safety risks on site and efficiency improvements offered through reduced operational costs.
CDE points out that its Oremax iron ore washing system is an adaptation of its established sand washing equipment technology. A typical CDE iron ore beneficiation plant could include components from its water treatment and recycling lines, and one of the company's competitive advantages is its focus on water treatment and recycling as an integral part of the process. Each plant can be designed to ensure maximum recycling of the water used in the washing process through inclusion of specialized equipment such as high-rate thickeners, flocculant stations and water storage tanks.
Why wash iron ore? According to CDE's technical literature, regardless of whether iron production for steel employs the blast furnace or sinter-plant approach, the objective is to feed the process with ore containing the highest possible Fe grade and lowest level of contaminants. For example, silica and alumina are considered contaminants; silica requires extremely high temperatures in order for it to be burned off, and the more silica in the raw material, the more energy needed for processing. Alumina in the raw feed creates waste buildup inside the kilns. The resulting kiln maintenance is an expensive process and one which steel producers are eager to minimize.
According to CDE's research in iron ore characteristics, the highest levels of contaminants exist in the finest particle sizes. The contaminants are of a much lower density than the target product; i.e., silica and alumina have a much lower mass than iron. Removing –60 micron material by efficient washing eliminates much of the silica, alumina and clay from the feed material. The direct result is Fe value as a percentage of the total feed is significantly higher than before the material was washed.
CDE said the washing process has been proven on a number of its recent installations in India and the company has delivered increases in Fe value from 54% to 62%.
There's also another factor involved, according to the company—costs. Conventional beneficiation of iron ore calls for raw feed to be delivered to ball mills which reduce it to less than 100 micron particle size, exposing the contaminants locked within the iron ore particles. The resulting feed is then washed and processed through multiple stages to eliminate low-grade waste. These plants are large—typically around 1,000 mt/h, and the resources required to make such as system viable ensure that a large number of operators within the industry are not able to afford or operate a full beneficiation plant. These producers do, however, still have an obligation to improve the quality of their iron ore reserves in order to maximize efficiencies and revenues.
CDE maintains its iron ore washing systems allow this objective to be achieved. The smaller-scale CDE system can be installed more quickly, in less space and for a smaller investment than a full-scale beneficiation plant. And, according to the company, while full beneficiation is able to increase the Fe value to a higher level than CDE's system, the difference in many cases is negligible.
Because the characteristics of iron ore can vary extensively in different regions within the same country, washing plant system success hinges on taking into account these individual variations and building the system accordingly. According to CDE, the fundamental difference between its ore washing systems and those offered by others is the CDE system is the only one that has been specifically developed to handle the individual characteristics of the feed material with a focus on achievement of the required results. Competing systems, says CDE, have been designed for applications that are quite different from iron ore processing and cannot deliver the necessary results.
In 2010, CDE Global and ProMet Engineers announced the signing of an agreement that the two companies said would enhance the options available to iron ore processors requiring beneficiation systems. The arrangement with Promet is aimed at development of a new suite of iron ore beneficiation plants aimed at small and medium sized processors. "We are focusing on the development of a range of iron ore beneficiation plants for operators requiring capacities up to 2.4 million tons per year," said CDE Asia Managing Director Manish Bhartia. "Up until now this is a segment of the market that has been overlooked by existing suppliers to the industry. The agreement we have signed with ProMet Engineers will allow for both companies to bring together their individual expertise to create new, innovative processing systems for the iron ore industry."
CDE identified this gap in the market following experience gained in recent years in the design and delivery of turnkey iron ore washing plants to steel producers in India. "The expansion of our offering to include full beneficiation is the next logical step as we seek to expand our market coverage in India," said Bhartia.
ProMet said it has developed significant experience working in the Australian and African markets through their offices in Perth and Cape Town and recently has been concentrating efforts on building a project portfolio in the Indian market. "We count some of the largest iron ore processing companies in the world among our customers," said ProMet Engineers Chairman Jim Cribbes. "Given this experience and the levels of iron ore available in India it is a market that is of significant interest to us. The new agreement with CDE will allow us to marry our process engineering expertise in iron ore processing with CDE's capability in the delivery of turnkey mineral processing projects."
In February, it was announced Shri Bajrang Power & Ispat appointed CDE ProMet as technical consultants for the development of an iron ore beneficiation plant to be located at Tilda in Chhattisargh, India. The plant will have a capacity of 2 million mt/y and concentrate from the processing plant will feed a 1.2-million-mt/y pellet plant currently under construction by Shri Bajrang Power & Ispat at the Tilda site.
Prior to that, in June 2010, CDE had announced that two of the largest steel producers in India—Bhushan Steel and Steel Authority of India—had purchased iron ore washing plants through its sister company CDE Asia.
Bhushan Steel is part of the Bhushan Group and is one of the emerging players in the Indian steel industry. Investment in a new iron ore washing plant from CDE is the latest in a long line of investments in new production facilities that have seen Bhushan Steel earn a reputation for bringing new technologies and processes to the industry. The ore washing plant is rated at a capacity of 425 mt/h and is located at the Bhushan steel plant in Dhenkanal in the state of Orissa. This is the largest plant installed by CDE in India, which noted that Bhushan's commitment to innovation in iron ore production included installation of a CDE Automat filter press within the processing system. The filter press allows for full closed-circuit water recycling, enabling 90% of the water used in the washing process to be reused and significantly reducing the volume of makeup water needed by the plant. In addition, the filter press reduces the footprint of the processing plant by eliminating the need for onsite ponds or settling lagoons to handle waste water from the washing plant.
"This plant for Bhushan Steel represents significant innovation in the way that iron ore is processed not only in India but globally," said Dr. Arabinda Bandyopadhay, vice president of technology and development at CDE Asia and the person responsible for working with Bhushan Steel on the specification of the new washing plant.
Another iron ore washing plant, to be located in Jharkland, was purchased by the Steel Authority of India, a company owned by the Indian government and the country's largest steel producer. This plant will process tailings from the existing production process to recover high-grade ores contained in the smaller particle sizes that their existing process does not capture. This will be achieved through installation of CDE's NanoWash system—a configuration of sumps, dewatering screens, magnetic separators and a cluster of hydrocyclones designed to effectively recover high-grade material from ultra-fine particles.
"Only through our ability to customize the iron ore washing plant to the very unique requirements of this project is it possible to recover the finest particles of high grade ores," said Bandyopadhay. "The delivery of this plant will recover material that has until now been a waste product and ensure the Steel Authority of India enjoy significantly improved processes and greater production efficiencies."
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