MINING PUMPS.
There are certain well-known difficulties and contingencies in installing and operating mine pumps: 1, The location of the mine is usually remote from supplies and any renewals or repairs which may be needed, are liable to be attended with excessive costs and delays; 2, The nature of the water in the mines is so highly acidulous that corrosion takes place in an incredibly small space of time. The action of sulphuric (diluted) acid which is found sometimes as high as two parts out of a hundred begins at once and continues until the iron or steel is destroyed; 3, The dust, grit, mud, etc., becomes mixed with the oil used to lubricate the pump; these ingredients find their way into the stuffing-boxes and cut the plungers.
Hence, ample and unusual precautions are made to overcome the foregoing conditions. Extreme care has to be used in securing all movable parts of the machine and the connecting pipes. The plungers are generally outside packed and handholes are arranged to permit free access to the water valves.
Fig. 438.—See page148.
Fig. 438.—See page148.
When pumps used in mining service assume large proportions, they are almost invariably described as pumping engines; there is no real difference between the two except the proportions. The same combination of engine and pump in the smaller sizes used for boiler feeding, etc., are called steam pumps.
Note.—The cost of repairinga half-inch globe valvewhich “gave out” in a mine in Venezuela, South America, was represented in a $45. machine charge and a mule ride of 35 miles to the shop containing a foot lathe and the same distance back to the mines. The cost in a more favorable location would be less than a dollar.
Note.—The cost of repairinga half-inch globe valvewhich “gave out” in a mine in Venezuela, South America, was represented in a $45. machine charge and a mule ride of 35 miles to the shop containing a foot lathe and the same distance back to the mines. The cost in a more favorable location would be less than a dollar.
The Cataract steam pump, Fig.437, is largely used in mining operations. Many years service has proved its peculiar and curious merits. Large columns of water may be raised to great elevation or forced against heavy pressures without shock or jar of any kind and with safety to the machinery and connections; abrupt and violent action of the water is also avoided.The Cataract, it may be explained, is a regulator invented by Smeaton for single-acting steam engines. John Smeaton, the inventor, was an English civil engineer born in 1724 and died in 1792. The device derives its name from its similarity to the optical disease—a cataract—as it is a supplementary or sliding cylinder with its piston attached very curiouslyto the main valve stem of the engine.
This cylinder—called the Cataract cylinder—is filled with oilwhich flows back and forth through a port connecting its two ends. This port is controlled by a valve which increases and diminishes the flow of the oil through the port. By means of the Cataract, the movements of the main steam valve are automatically graduated and controlled, so the speed of the piston is reduced as it nears the end of its stroke, allowing the valves to seat themselves gently and quietly, and the moving column of water to come to a gradual and easy rest.
The claims of this construction of pumps have been thus summarized—
1st.The speed of the piston is automatically slowed down at the end of its stroke, giving time for the column of water to come gradually to rest, and for the valves to seat gently and quietly, avoiding all concussion, jar, or the slightest tremor.
2d.The speed of the engine can be adjusted and automatically maintained as desired under any pressure.Should it be working under full head of steam and against a heavy pressure, and the pressure be instantly removed the speed would continue unchanged.
3d.The piston works to the end of its stroke under all pressures, avoiding the waste of steam incident to the piston falling short of its stroke.
It will be understood that there is only a slight waste of oil caused by the use of this apparatus—all the waste that there is, being the small amount leaking through the stuffing boxes.
The term “Isochronal,” pump meaning equal spaces in equal times has been applied to both these pumps and their valve gear.
The sizes, capacities, etc., of the pump described on the opposite page are given in the following
Table.
No.Diameterof SteamCylinderInchesDiameterof PlungerInchesLengthofStrokeSize ofSteamPipe161⁄2420 in.11⁄4in.2963 ft.11⁄2„31163 „11⁄2„41483 „2 „51894 „21⁄2„620101⁄84 „3 „722121⁄46 „31⁄4„825141⁄46 „31⁄4„930161⁄46 „31⁄2„No.OrdinarySpeedStrokeMaximumSpeedStrokeCapacityat ordinarySpeedin Gals.Capacityat maximumspeed inGallonsVerticalLiftinFeet150805285230227401101701803274011017029042740200300250520302753903206203032048032071522500750270815227001000250915229001300270
The above table is based on a steam pressure of 45 to 50 pounds per square inch of steam piston, and the vertical height is from lower end of suction pipe to discharge.
Fig.438is designed to show a pump largely used by miners in prospecting. It is double levered so that four men or more can operate it, two to each lever. The plunger and valves are so designed that they will lift muddy or gritty water without injury to these parts.
An electric mining pump is shown on page 276, part one. This is a portable pump mounted on a car running on rails and is designed for the work appertaining to a mine in steady operation.
On page 340, part one, is illustrated a powerful pump with four outside packed plungers designed for mining purposes.