CAT’S HUMUNGUS HAULER

It was an awesome and somewhat incongruous sight. Here, in a desert drag race, were two huge Caterpillar mine trucks — the production-proven 195-ton 789 and its latest sibling, the massive 240-ton 793 mechanical drive. They were lumbering flat out and fully loaded, neck and neck, up the 8% grade in the open pit Sierrita copper mine. It was an unconventional drag race staged earlier this year in the Arizona desert near Tucson, and it had ended the way Cat engineers had predicted — in a dead heat.

That surprising finish, considering the larger load of the 793, is attributable to a reduced ratio of gross vehicle weight to horsepower. In the 793 it is 384 lb./hp, while it is 389 in the Caterpillar 789.

Caterpillar’s 793 is the world’s largest mechanical-drive off-highway hauler. In fact, it is the only one in its class that features mechanical drive. Cat’s own tests show that the 789 surpasses 240-ton electric-drive competitors in cycle time and fuel efficiency, reaching 4.3% of the bigger truck’s production. And this despite the 789’s 23% lower payload rating.

Cat studies have also revealed that in uphill hauls with grades of up to 10%, the 789s outperform the electric drives by hauling 12.5% more tons per gallon of fuel consumed. Another plus, says Caterpillar, is that the mechanical drive trucks offer a higher gross power train efficiency at grades of up to 15%. According to Caterpillar’s figures, electric drive units reach peak efficiency at grades of between 5% and 8%. This means that incorporating Caterpillar trucks could mean less waste extraction because of the steeper grades that are involved.

At the time of the demonstration in mid-April, Cat had sold eleven 793s. The following are some of the notable features on the 793:

The engine is a Caterpill 3516 turbo-charged 16-cylinder diesel delivering 2,160 gross hp and 2,057 flywheel hp at 1,750 r.p.m.

The 6-speed powershift transmission is electronically controlled and delivers a maximum travel speed of 54 km per hour. Inhibited shifting, in which Antihunt prevents searching at shift points and a downshift inhibitor reduces the risk of overspeed, are both featured on this machine.

Standard features include electronic monitoring of vehicle systems, payload monitoring (including a real-time clock, data downloading capability to laptop computers for 1,400 cycles), a wet-roadway, electronic traction-assist rear axle, and automatic lubrication.

At the Sierrita operation, a P&H-2300 XPA shovel with a 28-cu.-yd. dipper required six passes to load the truck in under three minutes.

For those interested in staging their own drag races or in moring a mountain of ore as quickly and efficiently as possible, take note of the following reply card number.

Circle Reply Card No. 92

Micro-programmable Controller

Modicon Inc. of Mississauga, Ont. has introduced a Compact-984 micro-programmable controller. Measuring about eight inches long, five inches deep and five inches high, in a typical rack installation (cpu, power supply and i/o modules), the modular Compact-984 meets the requirements of both original equipment manufacturers and end users.

It is available with 1.5 k, 4 k, and 8 k of program memory in battery-packed RAM and is compatible with Modicon’s family of programmable controllers. Each of the three Compact-984 models — the 984-120 (1.5 k), 984-130 (4 k) and 984-145 (8 k) — can fit up to 256 discrete i/o in an area of only 1.5 sq. ft., arranged in one or two rows. And despite its space-saving footprint, the Compact-984 packs the 984 Family’s full, enhanced function set, the company says.

Circle Reply Card No. 93

High-density Backfill

Environmental concerns are making tailings ponds extremely unpopular. The recent Montreal River spill in northern Ontario provides evidence of that. But the extraction and processing of minerals always leaves a waste residue — a fact that no one yet has overcome. High-density backfill created from the fines residue taken directly from the mill may be a solution, however.

This kind of paste or thick fill was developed by Preussag AG Metall of Germany in the late 1970s. It has been successfully deployed at the Grund mine in Germany for years. The backfill has a density of 88% solids and a specific gravity of 2.2. It is pumped from the concentrator down the shaft (511 metres) and horizontally (1,500 metres) to an intermediate pump station. From there, it can be pumped up to 1,000 metres to the various stopes. Cement is added to the fill about 30 metres from the end of the pipeline. During shutdowns and on weekends the pump lines are left filled. There is no difficulty in starting to pump after these shutdowns, according to Preussag.

Fred Edwards, president of Dynatec Engineering, which has joined with Preussag and Mine Systems Design of Idaho to provide design of high-density, pumped-fill systems for North American mines, says dense fill offers several advantages over conventional hydraulic fill. These include:

* good support and stabilization;

* no water to pump and no spills to clean up;

* higher productivity and lower costs; and

* conventional milling and pumping requirements.

But the single, most significant advantage is that in using the fines from processing, tailings ponds can be reduced in size and, in some cases, entirely eliminated.

“There are only three mines in the world using this kind of dense fill technology,” Edwards notes. The trio of dense fill mines are the previously mentioned Grund, the Lucky Friday mine in Idaho and another in Austria, which, Edwards adds, has no need of tailings ponds.

Circle Reply Card No. 94

Diesel Filter

Engelhard Corp. has developed a “self-cleaning” diesel-exhaust soot filter that can remove 90% or more of visible smoke and soot. The trademarked DPX Soot Filter catalytically burns trapped particles to keep itself operating cleanly for hundreds of nearly maintenance-free hours.

The DPX reliably self-generates (burns collected soot) when exhaust temperatures rise above 375deg, a level often surpassed by diesel machinery in normal underground working conditions in Canadian mines.

The key to the self-cleaning feature is a proprietary, precious metal catalyst coating that lowers the temperature at which trapped particels vaporize. Non-catalytic soot filters can require frequent changeouts because of clogging.

Circle Reply Card No. 95

Compact Controller

Davis Controls of Oakville, Ont. has introduced the new CAL 9900, a fully programmable, self-tuning 1/16 DIN PID compact controller. The CAL 9900 is very compact (48×48 mm), yet possesses twice the processing power of its predecessor, the 9000.

The CAL 9900 is a universal controller, featuring full pid auto-tuning and a cool strategy for heat/cool applications with either air or water cooling options. Both heat and cool outputs have percentage adjustment and, in the event of sensor burnout, the main output can be controlled manually.

Circle Reply Card No. 96

Hydrocyclone

Krebs Engineers of Menlo Park, Calif. says it is offering the world’s largest hydrocyclone equipped with replaceable liners. The heavy-duty, 33-inch-diameter model is aimed at the high-volume, mineral-processing market in North America.

For use in coarse grinding and dewatering circuits, the new cyclone can be vertically or horizontally mounted and is designed to provide flowrates of 2,000 to 4,000 GPM (450 to 900 cubic metres per hour). For higher flowrates of up to 20,000 GPM (4,500 cubic metres per hour), the cyclones can be manifolded together in a multiple arrangement.

The Krebs cyclones are equipped with one-inch-thick, replaceable liners in each of the unit’s sections. The liners are highly abrasion-resistant and replaceable in the field when worn, providing economical operation and convenient maintenance. Also replaceable are the cyclone’s vortex finder and inlet head liner. A Krebs exclusive, the involuted feed entry configuration increases cyclone efficiency by minimizing internal turbulence.

Circle Reply Card No. 97

Magnetic Flowmeters

Users of
magnetic flowmeters have available to them a new family of variomag units from Endress and Hauser (Canada) of Burlington, Ont. These units are fitted with microprocessor-based transmitters that automatically compensate for temperature and aging drift. They feature a noise rejection element that eliminates inaccurracies caused by pulp and slurries and have a built-in totalizer display. Variomag is claimed to be maintenance-free, it has no moving parts, and no cleaning is necessary because the meter ignores non-conductive build-up on electrodes.

Circle Reply Card No. 98

Hot Idea in Footwear

For explorationists, hunters, skiers, abominable snowpersons or anyone else who desires toasty tosies, “Hotronic” Footwarmers are the thing. Made by Hotronic (Canada) of Calgary, Alta., the footwear is electronically controlled with four individual temperature settings connected to a micro-chip in the sock insole. A micro-processor is built into the battery pack that is clipped on the back or side of each shoe or boot. Depending on the setting chosen, the footwarmer will provide up to eight hours of heat. The batteries themselves may be recharged in excess of 1,000 times.

Circle Reply Card No. 99

U.G. Tailings Valve

A valve for underground tailings fill systems has been patented and is being manufactured by State Industries of Winnipeg, Man. For more than a year, the valve was tested at Inco’s underground operations at Thompson, 640 km north of Winnipeg. The manufacturers claim a life 50 times that of other valves and (interestingly enough, because of reduced turbulence in the pulp stream) an extension of the life of downstream pipework by as much as twenty-five times.

The essence of the improved valve design is its bulb shape, a form that reduces turbulence, and the interior lining, composed of a specially formulated polyurethane elastomer. The State Industries unit is known as the Thompson 4 Sandfill valve and is designed for coupling to standard 4-inch (or 10.2-cm) grooved pipe.

Circle Reply Card No.100

Shock Tubes

Atlas Powder Co. has developed a type of non-electric detonator shock tube that is reportedly four times stronger and more abrasion-resistant than standard tubes. The exel tubing is available in a wide range of millisecond and long-period delay detonators, according to Atlas Powder, a member of the ici World Explosives Group.

Exel shock tubes are made of a polymer-reoriented polyethylene monoplastic in an exclusive ici process.

Circle Reply Card No. 101