What, if any, are the differences between the United States and Australia and do these differences affect production and productivity from longwall mines? John Davis, managing director of International Mining Consultants, Australia, makes some observations.

Australian and American miners are the same - two arms, two legs and a cerebral computer on the shoulders. The longwall equipment in use in both countries is supplied by the same manufacturers. The coal seams were laid down in the same fashion using the same laws of nature.

What, if any, are the differences between the two mining nations and do these differences affect production and productivity from longwall mines?

When I was asked to write this paper I pondered the above statement and looked at the statistics in both Australia and the United States. I drew graphs of production, productivity and came up with explanations for the differences - wider faces, longer panel lengths and three-entry development.

I looked at the work ethics of both countries looking for something some of my fellow engineers may have missed. I then realised that there was nothing new in the information I was presenting, that numerous eminent Australians had travelled to the Mecca of longwall mining and developed hypotheses, gave explanations and in some cases implemented what they had seen.

Having worked in mines in most of the longwalling nations of the world, I decided to look at the problem from a different perspective. What are the reasons that one nation operates similar equipment and achieves very different results?

The fact is that some of the Australian mines achieve better results than some of the mines on the other side of the Pacific, so should the question be more "what are the reasons that one mine operates similar equipment and achieves very different results?"

In general, the panel width in the US is wider than its Australian counterpart, and the length substantially longer. (See Figure 1 and Figure 2)

This does not have a direct effect on the instantaneous productivity of the system, it does however, directly affect overall productivity through reductions in face end delays, the number of longwall change-outs, and development requirements. The wider faces in the US ensures that the bi-directional method of extraction is the predominant method of choice and more productive than uni-directional cutting at these widths. Also, because of the lower seam and extraction heights, more preferable, as the machine operators traverse the face only once for one full production pass.

The longer panel length reduces the number of longwall moves and therefore the amount of down time, obtaining better utilisation of the capital. As the faces become longer and wider other factors are introduced - providing sufficient air to dilute gas, dust and reduce temperature.

The American longwall is serviced by a three heading system, which is a legal requirement. Here in Australia we tend to use a two heading development with the obvious increase in ventilation resistance and reduction in volume through the face for the same loss of ventilating pressure.

Would wider and longer longwall panels be the answer for Australian conditions?

Mother Nature blessed Australia with thicker coal seams than our cousins on the other side of the Pacific. With the thicker seam section and the potential for greater output comes the problems of operational control and geological instability.

Although the principles of longwall mining remain the same whether it is a 2m or 4m extraction height, the practicalities are very different. The introduction of a small step into the floor of a 2m high longwall has little or no effect on its operation, however, the same step makes a dramatic difference when a 4.5m high support encounters the same obstacle.

With the thicker Australian seam section are the methods and practices used in the US suitable here?

Over the past ten years numerous Australians have visited mines in the US and brought back ideas and new methods to be introduced in our mines. A number of companies have brought managers and workers from the US to work in Australian mines. A number of mines here in Australia have been owned and operated by American companies.

Has the introduction of the “new ideas and management techniques” born any fruit here in Australia?

On the whole, the truth is that the best longwall mines in the US are currently out performing the comparable mines here. (See Figure 3) Why? What are the Americans doing different/better to us?

The answer may be as simple as the US train their managers and workforce to operate the equipment in their specific conditions.

With thicker seams at shallower depths and with different geology, Australian conditions are not the same as in the US. We both speak the same language, but are from different cultures and what motivates one may not be the solution for the other. Maybe we have been looking for a magical solution from America that does not exist. Let us use the expertise in this country to train our workforce to operate the longwall in our unique conditions.

This is an area of difference between the two countries and one which is not always recognised or dealt with. The training of our operators on thick seam longwall extraction is of paramount importance. The generic longwall training of the past is inadequate and has an affect not only on the productivity of the operation but also the safety.

How many times have we seen $60 million-plus spent on a longwall and associated equipment and then corners cut when it comes to the training? The training of the operators in a 4.5m thick seam section is far different from that of a 2m thick seam. The things that an operator can get away with in a thin seam will cause major problems in a thick seam.

The newer Australian mines have been designed with the infrastructure to accommodate the higher capacity longwall face equipment, where as some of the older mines are limited by infrastructure that was designed for non-longwall equipment or substantially lower capacity longwall equipment.

There is no reason why the new mines should not be comparable or better than the mines elsewhere in the world. We have the technology, we have the expertise and we have the resource to achieve consistently higher production from our longwall mines.

In our older mines we are using methods of operator control, which is familiar and comfortable but outdated. It is impractical to suggest that latest technology should be introduced to all longwall operations in this time of low commodity prices, but in some cases the technology we have installed is not being exploited. With the determination of management, the cooperation of the workforce and training, we can achieve better results from our older installations.

The mines in America adapt and use the equipment better in their conditions. We must do the same in our conditions and seam heights.

The thoughts and comments in this paper are those of the author and not necessarily those of International Mining Consultants.