Soaring maintenance costs and consumption of spare parts

The Nkomati Nickel Mine, established in 1997, is located in Machadodorp within the mineral-rich area of South Africa’s Limpopo Province. In 2007 Norsk ARM, the world’s third-largest copper producer and a major player in the global aggregates markets, acquired Nkomati, the only primary nickel mine in South Africa.

Nkomati’s operations are comprised of a large, conventional open-pit mine that feeds ore to the process plant, consisting of an Allis Chalmers Primary Gyratory crusher 54/75, Metso apron feeders, as well as a SAG mill and two parallel ball mills. Each ball mill feeds a hydrocyclone that separates acceptable product from material that needs further comminution.

Despite being a low-cost miner and producing a diverse range of end products, such as nickel, copper, chrome and platinum group metals, plunging metal prices have recently put the mine under considerable pressure to cut costs while maintaining or even increasing production.

Major reduction in unplanned breakdowns

Some of the mine’s main pain points were the extremely high consumption of spare parts and the high costs associated with that, as well as the need to improve the maintenance and reliability of key machines within the crushing, grinding and related process areas. Metso was asked for recommendations on ways to help get these cost areas under control.

After the first months with the recommendations in action, including new stocking guidelines in place and the weekly standing maintenance inspections implemented, immediate results were visible. The customer now has the advantage of being able to more accurately forecast expenditures and guarantee equipment reliability, thus resulting in a drop in overall costs.

Metso has also been made the exclusive supplier of the needed parts; this not only helps to ensure that all spare parts are available when needed, but that they meet OEM standards for fit, form and performance. The end result is that there is a major reduction in unplanned breakdowns and an increase in plant availability and reliability. These factors have improved process recovery and helped with the mine’s cost reduction initiatives.

Customized maintenance and inspection plans

How was this achieved? The first step involved regular inspections of the equipment in order to identify and quantify the areas of most frequent concern. With the initial inspections completed, a key finding was that a shortage of the correct replacement spares was causing major delays and adding additional costs during some of the unplanned breakdowns. A systematic and focused approach and evaluation of historical trends identified the key problem areas that needed to be addressed.

With these findings, the Metso team laid out an improvement plan that would help to make the equipment more reliable and also ensure the proper spares inventory was on hand when problems did occur.

Metso first attacked the issues surrounding the availability of the needed wears and spares, while the mine focused on some of the outstanding issues in the process section of the plant. Inventory levels were optimized, with stock requirement levels set and managed for crucial spares and wears.

Continuous equipment inspections and procedures were established. These were followed by monitoring the availability of the identified critical spares plus replacement planning within the newly established maintenance program. The program included weekly inspections with continuous evaluations, monitoring of stock requirements and planning, all in collaboration with the customer.