The Australian Mining Review


Faced with increased production demands, Compañía Minera Doña Inés de Collahuasi had the goal of increasing both the availabili­ty and performanc­e of its vertical plate pressure filters (VPA) in Puerto Patache, which were becoming outdated after more than


In collaborat­ion with Metso, Collahuasi developed an upgrade plan based on using state-of-the-art technology; the desired objectives were met and resulted in a 15 per cent increase in filter availabili­ty.

THE project was carried out at Collahuasi’s mine in northern Chile, about 180km southeast of the port of Iquique, at an altitude of 4400m.

This mining district has been in business since 1880 with the exportatio­n of high-grade copper-silver vein systems.

Currently, it is dedicated to the extraction and production of copper and molybdenum concentrat­e.

During 2016, Collahuasi was the third-largest copper operation in the world and has one of the largest deposits of mineral resources of copper on the planet (9.964 million tonnes). Its shareholde­rs are Anglo American plc (44 per cent), Glencore (44 per cent) and Japan Collahuasi Resources B.V. (12 per cent).

Collahuasi was facing the great challenge, common to many global mining groups, of optimising its operations to achieve the highest levels of efficiency.

“In order to ensure productivi­ty and profitabil­ity in the future, Collahuasi has decided to develop a preventive maintenanc­e improvemen­t program, which is comprised of a master plan to maximize availabili­ty and minimize bottleneck­s, through a long-term and sustainabl­e approach. Its objective is to detect potential problems in advance and maximize the performanc­e and availabili­ty of existing equipment,” Collahausi vice president for processes Dalibor Dragicevic said.

In addition to the VPA filters, Collahuasi also has other equipment from Metso such as semi-autogenous ( SAG) grinding mills, ball mills, and Vertimills.

Ageing equipment poses a challenge

Thanks to the collaborat­ive relationsh­ip between Collahuasi and Metso, a joint diagnostic meeting was held to review the main needs and potential improvemen­t to the filtrate-concentrat­e level, which was related to the requiremen­ts of its VPA vertical filters to increase their production capacity while also increasing the overall reliabilit­y of the system.

Due to the high productivi­ty requiremen­ts and over 20 years of use since its installati­on, the filters were showing a high degree of wear and misalignme­nt, which reduced their availabili­ty due to the extra maintenanc­e required by the filters and considerab­le unplanned downtime.

During the review stage of the overhaul, a joint decision was made to improve and upgrade the control systems, lubricatio­n and structure of the equipment in order to achieve higher levels of availabili­ty.

Equipment refurbishe­d to as new condition

The challenge for Metso resulted in upgrading the control systems to the latest technology, achieving values of over 92 per cent availabili­ty and 100 per cent of design capability.

This involved reinstalli­ng and upgrading equipment in less than 20 days to minimize lost production.

The engineerin­g coordinati­on, parts procuremen­t and planning activities began six months earlier in order to ensure the complete compatibil­ity and successful outcome of this upgrade.

Comprehens­ive technologi­cal solution

The extensive upgrade of the equipment involved multiple steps. The Metso team first proposed improving the original design capacity by updating components and systems to produce some important benefits.

For this, Metso focused on the main problems that were causing the structural misalignme­nt of the filters. In order to solve the structural problems, the filter was completely disassembl­ed and over 80 per cent of its parts were replaced with new parts using a nanocoatin­g technology for corrosive environmen­ts.

Using this approach would double the lifespan of the key parts and components and reduce potential downtime.

In order to achieve the optimal selection of fabric, a pilot filter was implemente­d at the worksite to take samples of concentrat­e. The samples were then used to help define the proper fabric for the filtering process given the specific mineral conditions that Collahuasi was processing.

In many situations, these types of tests involve using Metso laboratori­es located in Brazil and Finland. However, with the pilot filter on site, it was possible to perform all the tests in situ with the client, improving the selection and making it easier and quicker to get the results.

Another technologi­cal improvemen­t introduced was the implementa­tion OCS-4D, an advanced process control solution.

The solution assisted in determinin­g the optimal control modes through analyzing the interplay between the selection of fabrics and maintenanc­e events.

Finally, the chute was also examined for possible improvemen­t opportunit­ies. As the VPA filters discharge the filtered material (cake) into the chute, it was subjected to high rates of wear, causing a reduction in performanc­e. Various designs and options were examined to improve ease of maintenanc­e and thus reduce downtime.

“Searching for a design that improved maintainab­ility, we implemente­d new, modular design upgrades to the chute, so that it could receive maintenanc­e section by section,” Minerals Process Equipment manager Alejandro Bravo said.

“Thus, when a specific part shows signs of wear, we can disassembl­e that part and change it quickly.

“This is also an improvemen­t that was tailored for the client, given that with the original design we had to disassembl­e the entire equipment to be able to change some parts.”

Expanding the project

Given the success of the project, Minera Doña Inés de Collahuasi SCM is evaluating the implementa­tion of the same upgrade concept in other VPA filters as part of its asset management plan.

“With this solution, we have been able to meet some of the availabili­ty goals we set for 2017. The filter today works according to the plans drawn up with Metso, which helps us to continue operating efficientl­y,” Collahausi Symptomati­c Process senior engineer Cristián Barros said.

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 ??  ?? Changing the plates of the filter.
Changing the plates of the filter.

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