Use of X-ray fluorescence spectrometry for analysis of iron and other constituents of drill hole samples, plant products, etc. has replaced the traditional wet chemical methods in many applications. Spectrographic oil analysis and other condition monitoring techniques have assisted in minimizing loss of equipment availability due to premature failures.

On-stream analysis of iron and alumina by measuring the back scatter gamma radiation of irradiated ore has been developed in conjunction with CSIRO and is in the prototype testing stage on product conveyors in the Hamersley system. Integrated with weightometers, its potential lies in operational product quality control during blending and shiploading functions replacing the more time consuming sampling, sample preparation and assaying. Similar application for down hole in situ analysis is under investigation.

Some of the more spectacular use and development of modern technology has occurred in the iron ore railway operations. These systems operate the largest and heaviest trains in the world utilizing head-end power only. They have increased in Hamersley from combinations of one head-end locomotive and 76 wagons with 9000 t gross load to the current configuration of three head-end locomotives and 200 wagons with a gross of 25,000 t. This improvement has resulted in part from the local development of a train simulator which enables prediction of the forces generated in the long and heavy trains, knowledge of which enables the formulation of appropriate operational driving strategies. These are further refined by analysing the drivers' actual control actions recorded on locomotive data loggers.

Asymmetrical rail profile grinding to ensure better wheel and rail interface, developed in conjunction with Mt Newman Mining, is now almost standard practice world-wide.

Another development with CSIRO is a semi-continuous rail profile measuring device. The equipment mounted in a rail car measured rail profiles at 5 m intervals along the track whilst moving at speeds of up to 80 km/hr. Locally developed computer programs produce 'real-time' results.

The days are now long past when large rail gangs are required to work manually in almost intolerable conditions to replace sleepers. In a major sleeper replacement program in which modern technology concrete sleepers are substituted for the original wooden ones, Hamersley's rail maintenance contractor employs an automatic sleeper laying and track relining machine which automatically, whilst travelling along the line,

• spreads and lifts the rails
• removes the old sleeper
• positions a concrete sleeper
• replaces and fixes the rail and
• tamps the ballast

New and old sleepers are stored on a trailing section of the machine.

Other innovations in the rail system include

• 'hot-box' detectors to identify high bearing temperatures on ore wagons 'on the move'
• track side detectors to locate dragging equipment such as broken axles, air hoses, etc.
• track research wagon to monitor track conditions
• stream flow level detectors which warn of high-water levels in culverts via the CTC system.

In the exploration field conventional methods are now being supplemented by the latest geophysical methods (gravity, aeromagnetic, sedimentology, etc.) to select hidden or 'blind' drilling targets. Use of Landsat imagery has greatly facilitated exploration planning, map making and geological interpretation.

Australian Academy of Technological Sciences and Engineering