Cableways
A cableway consists essentially of two towers or masts between which is supported a fixed cable, along which a carriage can be hauled, back and forth, by means of a hauling rope actuated by an engine; in addition a hoisting rope, also actuated by the engine, is attached to the carriage and by means of it the load carrier or carriage can be raised or lowered, through a set of sheaves (f ig. 11, 12).
For alluvial work, the load carrier should be self-dumping. The general method of operation is as follows; the excavated material is loaded into the carrier, which is then hoisted by means of the hoisting rope and hauled along the fixed cable to a dump box or bin, where it is automatically dumped; from this bin the gravel is fed to the sluice boxes or treatment plant. The excavated material has usually to be trammed to a central stock pile under the cable for convenience in loading the carrier. This can be avoided, however, by the use of a radial cableway, in which the tail mast – i.e. the tower farthest from the treatment plant - can be propelled in any direction to suit excavating operations.
More efficient type of cableway for alluvial mining is the slack-line cableway dragline excavator, which combines the operations of excavating, conveying, and elevating, all in one installation; by means of it material spread over a large area can be concentrated at one point for treatment. In this type, also, the tall mast can be moved in any direction to suit digging operations; slack-line excavators are reputed to be capable of excavating to a depth of about 70 feet below ground level.
WASHING PLANTS
Washing plants used in conjunction with stream shovels, dragline excavators, etc., are usually mounted on wheels, caterpillars, or pontoons to increase flexibility and to make the of the plant, from one point to another, easy, such plants generally consist of trommels followed by sluices, although in some cases jigs and flotation units are installed; where water is scarce, classifiers are usually installed for dewatering the tailings and thus reducing the amount of water consumed.
Fig. 11. Diagrammatic sketch of cableway
Fig. 12. Henderson radial cableway
COMPREHENSION CHECK
Exercise 16. Complete the sentences using the information from the text.
The shovel is employed to excavate the material which is then loaded into … for transport to the washing plant, a method which involves the use of trucks, rails and perhaps locomotives, all of which increase the … .
The base, revolving frame, and main machinery units of the shovel are similar to those of the dragline excavator, but the … unit is entirely different. The digging unit consists of a jib or boom, which rotates horisontally, carrying the … supported by a derrick.
Scrapers are well adapted for the working of ... deposits, underlain by a soft, even bedrock a deposit having a hard оr pockety ... is unsuitable for scraping. When stripping overburden the scraper equipment is so arranged that in making the first cut the overburden is ... beyond the pay boundary. When excavating, gravel, the scraper may be hauled up an incline to dump its contents over a grizzly into a ... which feeds the sluice boxes or washing plant, or it may … the excavated material into trucks to transport to the treatment plant. A cableway consists essentially of two ... between which is supported a fixed cable, along which a carriage can be hauled, back and forth, by means of a … rope actuated by an engine.
Exercise 17. Discuss the questions with the partner.
Washing plants used in conjunction with steam shovels, dragline excavators, etc., are usually mounted on … (what?)
Washing plants generally consist of trommels followed by … .
More efficient type of cableway for alluvial mining is the slack-line cableway dragline excavator, which combines the operations of ...
It is possible for the shovel to deliver the excavated material to a storage bin, but this ... .
Scrapers have been employed successfully in the mining of …
Scrapers of which there are many forms and sizes a operated by … .
After a paddock has been worked out by means of a scraping plant, it is usually necessary to make a … .
Exercise 18. Look through the text and find the English equivalents for the Russian phrases.
система откатки; использоваться в соединении с: грузить в автосамосвалы; увеличивать расходы; доставить добытый материал; залегать; водообеспечение; дорогостоящие простои; двигаться вертикально; в пределах радиуса машины; мягкая ровная подстилающая порода; неудобный для разработки скреперами в направлении уклона россыпи; складировать пустую пород; сделать первый разрез; сделать последующие разрезы; избегать; вручную; место разгрузки.
Exercise 19. Continue the sentences using the information from the text
Power shovels are used for ...
In comparison with dragline excavators power shovels employ … .
A power shovel consists of ... .
The digging unit acts in the following way ...
Power scrapers are used in the mining оf ... .
Scrapers are operated by ...
The hoists may be driven by ...
In commencing operations, it is advisable to start at the …
When excavating gravel the contents are dumped into ...
A cableway consist of ...
The general method of cableway operation is as follows ...
A more efficient type of cableway for alluvial mining is the ...
Washing plants are mounted on ...
Exercise 20. Look through the text below and think of the title to it.
Eleven of the 40 cable bolts used were equipped with load cells to monitor changes in the cable force after emplacement. These cable bolts therefore required slightly different fabrication procedures. Each strand of a monitor cable bolt was greased and encased in a 1/2 in. diameter PVC tube except for the anchorage section. That section was completed in a similar manner to the regular cable bolts. The greased strands forming the stressing section were therefore able to permanently slide back and forth in the PVC tubes after the cable was installed.
Following fabrication, the cable bolts were ready for emplacement in the cleaned hole. Small cable bolts consisting of up to 8 strands may be placed by hand using 3 or 4 people to simply push the cable to the bottom of the hole. Larger numbers of strands become difficult to handle and require the aid of a tugger. The tugger is used in combination with a snatch block placed near the hole collar. This allows the tugger cable to exert a pull on the cable bolt where it enters the ground and force it down the hole.
Exercise 21. Read the headlines in text 4 and say what you know about the equipment. Discuss it with your partner. Then read the passage and find the facts supporting your ideas.