The latest survey of operating levels and key productivity yardsticks at longwall mines in the US and Australia has given operators some interesting comparative data to chew over.
In an attempt to determine key performance indicators (KPIs) most often used to measure longwall performance, US-based consulting company Norwest Corporation surveyed longwall mines in America and Australia. Out of a total of 48 operating mines in the US, 31 (65%) responded while in Australia, 10 of 32 (31%) responded, amounting to just over half of Australian and US longwalls reporting KPI data.
Information collected related to the 2002 operating year.
The value of benchmarking data clearly lies in allowing a mine to measure itself against a KPI, or, as survey author, Norwest senior vice president Bob Evans, noted: “Knowing current industry benchmarks is another piece of the puzzle in achieving world-class performance.”
Each mine’s KPIs will differ, depending on its market, geology, and infrastructure constraints and it is unlikely that any mine will lead in all of the performance areas measured by the KPIs used in the Norwest study. A key observation is that the large gains in productivity won by capital investment in larger, faster, more automated equipment have begun to slow. For the first time in 20 years US longwall mines recorded two consecutive years of declining productivity, Evans said. Longwall production in Australia dropped in 2002 largely due to the closure of eight Australian longwall mines.
Information related to a number of KPIs was collected but only some of this is being released publicly. Mines that participated in the study receive a full report.
Information from 74 Australian and US mines indicates the average longwall panel length is 2451m. The longest panel was 4572m while the shortest was 460m. Some 45 mines operated panels averaging between 1200-3600m. Across the two countries, longwall cutting height averaged 2.6m with a minimum of 1.2m and a maximum of 4.5m.
The web width of the longwall shearer varied from a maximum of 122cm to a minimum of 23cm with the average at 96cm. The web width had generally increased over time, Evans said. Conveyor widths have also progressively increased over time and in 2002 the average width was 1016mm, with a maximum of 1342mm and a minimum of 732mm.
Different approaches to measuring longwall production meant three types of data were collected. This included tonnes, metres of retreat and passes, each measured for a 24-hour period. Average daily longwall production in 2002 (metres retreated) was 14m, with a maximum of 29m and a daily minimum of 6m. Roughly a third of respondents averaged 12m per day. Longwall production in passes averaged 15 per day with a minimum of eight and a maximum of 29.
Longwall panel size has been increasing steadily over the years and 2002 figures showed a maximum panel width of 336m, an average of 251m and a minimum of 48m. Roughly a third of respondents had face widths of 270-300m.
“Management of the longwall move process is a very important part of controlling costs at longwall mines,” Evans said. The survey asked operations to report move times from last coal produced on the old face until first coal is produced on the new face. The average longwall move took 14 days with the quickest done in four and the slowest taking 33 days.
Evans said more emphasis was being placed on continuous miner (CM) productivity in longwall development. Daily production from CM development ranged from 4000 tonnes per day (run of mine) down to 325tpd. Average production was 1742tpd. The best mine reported 253m advance per day while the poorest was managing 28m. The average was 85mpd.
“More advanced equipment is still available but the appetite for spending capital has diminished as the gains are not as lucrative as before,” Evans wrote in the final report.
“It is still important for companies operating longwalls to strive for continuous improvement. Accepting past performance as the standard will lead to long-term failure because it has been necessary to improve just to stay even.”
