Published in Australia's Longwalls

There are a number of possible explanations for the increased production – increased nameplate capacity, operating hours or cutting rates to name a few. The role of utilisation in the increase, however, is an interesting issue.

Consulting company McAlpine-B’s utilisation benchmarking program U_Gap was used to calculate utilisation for the period. Publicly available Coal Services data was used to calculate production utilisation (PU).

Utilisation is normally defined as the time spent in production-related activities divided by the number of hours in a year. But this definition discriminates against five-day mines which do not operate on weekends. The concept of production utilisation overcomes this. It is defined as the time spent in production-related activities divided by the scheduled number of hours planned for production-related activities. Thus weekend hours are excluded for five-day mines as no production related-activities are normally undertaken at this time.

The advantage of the PU is that it allows for meaningful comparisons between mines that have different scheduled operating hours (eg five-day vs seven-day mines).

Using the PU measure, best practice utilisation is 61%.

Production, hours of operation and nameplate capacity were averaged for the years 1998–2003. The results show that for the average mine, production increased by 26% over the period 1998–2003. The average number of operating hours increased by 17% for the same period. Obviously output will also increase if the number of hours available for production also increases.

Nameplate capacity increased by 22% for the period. If more powerful equipment is installed, then obviously more tonnes will be produced. Thus most of the production gains are due to increased nameplate capacity and increased operating hours.

Surprisingly, utilisation fell by 9% from 45% in 1998 to 41% in 2002. In 2002 Kestrel and Appin were clear winners in the utilisation stakes, but achieved lower levels of utilisation in 2003.

Given that the utilisation of the average Australian longwall is 41% and the benchmark is 61%, there is significant room for improvement in many Australian longwall operations.

By Graeme M Baird, McAlpineB

Fig.1 1998-2003 Performance Analysis: Summary Table 1
Average Mine	1998	1999	2000	2001	2002	2003	% Change 1998 -2003
Longwall production (Mt)	2.17	2.10	2.53	2.83	2.90	2.73	26%
Available hours per year	4,920	4,962	5,112	5,719	5,673	5,747	17%
Nameplate capacity (tph)2	2,480	2,548	2,894	3,010	3,045	3,023	22%
Utilisation (%)	45	43	46	42	44	41	-9%
Source: JCB statistics 1998 to 2003 Conveyor capacity is used as a proxy for nameplate capacity