Wheeled excavators

Fig. 7. Mining with a bucket-wheel excavator, where (-) represents the ultimate si2e of the dyke.

Draglines are equipped with a 71-m bucket at the end of a 111-m boom and can be employed to dig both a portion of the overburden, which is free-cast into the mining pit, and the tar sand, which is piled in windrows behind the machine. Bucket-wheel reclaimers, similar to bucket-wheel excavators, load the tar sand from the windrows onto conveyor belts which transfer it to the plant. 

This difficulty in translating what appears to be a simple technique in a beaker to a viable continuous process contributed to the failure of many subsequent pilot plants. It was not until 1967 that the first commercial plant was put on stream, using giant bucket wheel excavators to mine the sand, the hot water process to separate the oil, centrifuging of the froth to remove solid and water contaminants, delayed coking of the bitumen to produce a sour distillate product, followed by hydrofining to produce a "synthetic crude oil. 

In the Suncor pit design, the ore body is divided into two layers, or benches, each nominally 23 m high. The pit floor and the dividing plane between the upper and lower bench are roughly horizontal and 8000 ton/ hr/hr bucket-wheel excavators are employed as the primary mining equipment. Tar sands loosened from the face of each bench by the bucket wheels are... 

The preparation of the site may well involve the removal or de-branching of trees using chainsaws and a wheeled excavator to remove the roots. These are particularly hazardous operations when there are overhead or buried power lines at the site. 

A weekly inspection of a 360° wheeled excavator would include the condition of the tyres, wheels, steering controls, lights, brakes and hydraulic systems. Periodically, the seat rigidity and the proper functioning of seat restraints, instrumentation and controls, bucket condition and other attachments need to be inspected. Appendix 13.2 gives an example of a typical risk assessment used for an excavator. 

Identify the weekly maintenance inspection requirements for a 360° wheeled excavator. 

Besides the above-mentioned "classic" overburden handling machines, other types of machine are used for special purposes or under special conditions, such as face shovels, scrapers, scraper-dozers, wheel loaders, crawler loaders, possibly even bucket ladder excavators or small bucket wheel excavators. 

Gottvald, J. Kala, Z. 2012. Sensitivity analysis of tangential digging forces of the bucket wheel excavator SchRs 1320 for different terraces. Journal of Civil Engineering and Management 18(5) 609 20. doi 10.3846/13923730.2012.719836. 

Impact loads on booms of bucket-wheel excavators used in opencast mining engineering... 

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