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Standard approach needed to maintenance, downtime on mines

23rd June 2017

By: Marleny Arnoldi

Deputy Editor Online

     

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If the mining industry could standardise maintenance and downtime procedures, it would help “tremendously” to facilitate more efficient, cost-effective, faster maintenance, says capital plant equipment manufacturer Halley & Mellowes group of companies (HMA).

HMA sub-Saharan Africa GM George Hoffmann tells Mining Weekly that maintenance can have a significant impact on total cost of ownership if downtime takes place too often or over long periods.

Another hindrance to effective maintenance is the specification of the incorrect product for an application, as this will lead to unscheduled downtime owing to product failure. Hoffmann notes that using the correct product will ensure the best life expectancy and plant availability for mines, ultimately improving total cost of ownership.

It might be that customers are not aware of what is available on the market, or not enough testwork has been done to identify the correct product. Another problem is the original- equipment manufacturer (OEM) offering one material, without improved wear life, for example, and, on the basis that they provide good service, the customer continues to buy from them.

“It is not always a case of an incorrect product that is specified, but we are able to use our experience to identify the need for a better suited alternative product,” Hoffmann points out.

He relays that total cost of ownership is a function of direct expenditure and lost opportunity costs. Therefore, maintenance should be kept to a minimum without jeopardising plant productivity with breakdowns.

Product Progress
Hoffmann notes that to keep downtime at mines to a minimum, HMA continuously develops products to improve the ease of maintenance and lower the need for maintenance.

“Over the years, to improve the life expectancy of wear liners, HMA has developed a range of products that includes material- related products, dead-box-related products and multimaterial products.”

HMA’s product offering includes polyurethane wear liners, which are lighter than traditionally used steel, have built-in wear indicators to simplify preventive maintenance planning, are easily cut and drilled into and are faster to install than steel liners.

“We also continuously improve the efficiency of our installations. The areas we have improved on the most include preparation planning, existing lining removal, adhesion methods and tooling,” Hoffmann points out.

Case in Point
To enable better productivity and reduced downtime for maintenance, HMA’s international HMA Wear Solutions division this year refurbished 380 mm dewatering cyclones, which are used for coal mineral processing, for mining company Rio Tinto, in Queensland, Australia.

The cyclones were originally lined with 12 mm alumina tiles; however, the group’s client requested that their service life be extended.

HMA lined the cyclones with HMA’s alumina/SiTech hybrid lining, comprising engineered alumina tiles in the inlet head and HMA SiTech monolithic linings in the cone sections.

SiTech is a fine-grain ceramic with a matrix hardness similar to that of the main ceramic particles, which provides a hard-wearing surface.

After being in service for about 14 months, the products were inspected and the company found no signs of measurable wear in the HMA SiTech components.

Hoffmann explains that they could have functioned for longer, but were, however, removed based on changeout schedules determined from experience with the previous lining material.

As a result, the internal parameters of the cyclones are now maintained for a longer period, which provides improved cyclone performance and yield over the same period.

“Improving and maintaining cyclone performance for a longer period is critical to overall plant performance and any downstream processes,” HMA states.

The company also recommended the removal of the nozzle flange joint and lining the cyclone completely from the inlet head through to nozzle discharge with HMA SiTech, removing the potential failure point.

HMA’s design comprises special joints between SiTech components to overcome fines ingress at joints.

The second recommendation was the replacement of the inlet head alumina tiles with a one-piece HMA SiTech liner. This increases the service life of the cyclones, replicating the minimal wear of the SiTech liner in the lower cone sections leading into the inlet head.

As all cyclones act under centrifugal forces with sliding abrasion on the internal lining, the removal of tile joints provides a smoother surface, which results in less turbulence and improved cyclone performance.

The throughput increase of around one- million tonnes had already achieved a return on investment great enough to cover the cost of further upgrades.

The expectation is that the frequency of cyclone replacement will decrease even further, enabling each run cycle to handle more throughput than before.

The flow on benefits from this are that the material cost per ton reduces, along with the cost of labour to replace the cyclones, considerably decreasing a customer’s total cost of ownership.

Edited by Tracy Hancock
Creamer Media Contributing Editor

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