The Canadian Engineer, 1 Dec 1910, p691-4 and 697
Rock-Crushing Plant of Messrs Laurin & Leitch
Paul C Van Zandt
The rock-crushing plant of Messrs Laurin and Leitch engineers and contractors, Montreal, Canada, is unusually interesting from its enormous capacity of production and remarkable flexibility of operation.
Having obtained from the Montreal Water and Power Company, the contract for constructing within four years a reservoir of 43,000.000 gallons at Outremont, one of the city’s suburbs, they recognized the advantage of crushing and marketing the rock at the time the excavation is made instead of piling it on a waste bank, the usual custom in the past.
As the reservoir will be 800 feet long, 400 feet wide and 40 feet deep, formed partly by excavation and partly by enclosing walls, it will be necessary to crush within four years approximately one million tons of hard trap and granite rock and to provide storage for approximately one hundred and fifty thousand tons in various sizes after crushing so that it can be marketed to the best advantage.
The limited time at the disposal of the contractors and the enormous quantity of stone to be removed within that time necessitated the erection of one of the largest rock crushing plants in the world.
The site of the reservoir from which the rock is quarried is upon the north slope of Mount Royal, and quarry operations have been started at the lowest point in the reservoir site, where an excavation of approximately twenty feet has been commenced. From this point the quarry face will be gradually cut back towards the mountain parallel with the lower edge of the reservoir. The rock as fast as quarried is loaded direct by steam shovels into six yard side dump quarry cars, which are made up into trains of four each, to be hauled to the crushing plant. The rock is drilled by Temple electric drills along the quarry face which is 800 feet in length, and after blasting the cars are brought to the proper location alongside of the steam shovel, close to the bank of blasted rick, by Shay locomotive, which is 6’ the geared type so s t take the grades, pushing the empty cars up to the quarry face, and bringing the loaded cars from the quarry face to the bottom of the incline haulage system leading from the lowest point in the reservoir to the crushing plant.
The crushing plant is advantageously located upon an excellent site about 1500 feet from the centre of the reservoir, and to bring the rock from the excavation to the crusher a haulage system has been installed operating in balance, drawing a train of four loaded cars up the haulage incline of about 4 per cent, to the foot of the two incline trestles leading from the ground to the dumping hopped over the large crusher. At the same time, a train of four empty cars is lowered down the haulage incline back to the quarry, balancing in part the up-going load. At the upper end of the haulage incline there is a third track for empty cars, and the trains of loaded cars which are gathered upon first one then the other of the two outside tracks shown upon the cut accompanying this article, are hauled up these incline trestles of approximately 20 per cent grade, one at a time and alternately upon each of the two trestles as shown in photo 776, so that the large crusher is receiving a carload of rock first upon one side and then upon the other, making its operation almost continuous.
The reservoir, which will be the largest in Montreal, was designed by Frank H Pucher, Chief Engineer of the Montreal Water and Power Company. Approximately one-half of this reservoir is to be completed first and put into operation, while the remaining half is being completed. The main water pipe leading from this reservoir is now being laid by Messrs Laurin and Leitch, and consists of a line of 60-in cast iron pipe, the laying of which, with its valves, etc., is in itself as item of considerable interest, but which is dwarfed in comparison with the quarrying and crushing operations going on.
This plant is unusual in many respects: primarily on account of its size and initial cost in proportion to the amount of work to be done under this contract. The size of the plant and the excellence of its equipment are resulting in a saving in the cost of construction of the reservoir, and the disposal of the rock taken from it which should pay for the entire equipment. It has sufficient capacity to crush the rock as fast as taken from the quarry, so that the product can be marketed immediately after excavation. The rock is handled but once from the excavation to the marketing, and in this way it is immediately disposed of and is out of the way. The rock is excellent in quality and instead of being thrown away on a waste bank, as was the case of the rock taken from the excavation for the Chicago drainage canal, for example, is made to yield a profit. Messrs Laurin & Leitch use a very great quantity of crushed rock in their own work on other contracts, noticeably, street paving, concrete work, and other engineering work of similar character, and a portion of this rock will be used in this way, the cost of which will be less to them than rock purchased upon the open market. The plant, which was designed and equipped by the engineering force of Allis-Chalmers Company, possesses an unusual flexibility of operation in addition to unusual economy of production, so that it may be operated to suit both the work of excavation and the market for crushed stone, producing rock for the lowest possible cost of production. The plant is exceedingly compact, resulting in the smallest possible buildings, and is well arranged for operating with the smallest crew of men. One man handles the hoisting and haulage equipment, tow men the dumping of cars and feeding of crusher, two men the handling of cars at the foot of the incline trestles, one man for the spring floor, one man for the number sixes, one man for the transmission and hoist floor, one engineer, two boiler men, one oiler and two men upon the conveyors, loading, etc. and these men constitute the entire operating force of the plant. One side of the haulage incline may be operated independently of or without the other. Any one or all of the number of sixes maybe cut out temporarily, and when the balance of the plant is shut down rock may still be loaded or piled on the storage piles, or the drills at the quarry may be operated.