Show safety and economy in n mine min e Vent ventilation ilat ion by B E al C E rock heat at depths greater than 1000 feet frequently becomes a matter of considerable importance in mine ventilation in the tonopah mines except those in the western part of the district the temperatures in the deep workings are sufficient to cause inconveniences that seriously affect the payroll pay roll no man can put forth the same physical exertion in a hot sultry atmosphere mo sphere that lie he can in cool well ventilated places it is evident that a greater number of men will be required to produce a given tonnage from a hot mine than would bo be required to produce the same tonnage from a cool mine thus the payroll pay roll Is greater and the cost per ton is increased to reduce the cost per ton by increasing the output per man is the aim of every mine manager in the world and is most generally attempted by efforts to stimulate or to drive the employees to extra exertions this method leads to dissatisfaction and to frequent changes in the payroll pay roll the proper method is to make the conditions underground such that men can accomplish a fair days work without exhausting their physical system and without undue fatigue work would be done by machinery whenever possible and an intelligent employee should be used merely to direct the power of the machinery along the most advantageous lines the machinery cannot think but the man who directs it must do the thinking for the machine this brain power of the machine must have the stimulant of good air and to accomplish this condition the mine manager provides some method of ventilation usually by blowers or exhaust fans and sometimes by connections through the workings with other mines or outlets in the latter case caise it is the rock heat or underground temperature that provides the required ventilation there ther e are many mines where the managers do not know or to not stop to realize the causes for the draughts in certain directions ions and this is particularly true among the metal mines of the west for the metal miners have not been taught the science of ventilation as the coal operators have the cause of draughts is that the air in the underground workings becomes heated by rad of rock heat to the temperature of the air on the surface the heated air expands and becomes lighter as it becomes hotter the hotter it gets the lighter it becomes and the lighter air seeks the path caf h of least resistance in its efforts to rise and Buckeye Belmont mines co tonopah To nevada make its exit from the mine cold air from the surface immediately rushes in through some other passage way to take the place of the heated air that passes out and this in turn becomes heated and follows the same course as taken by the previous volume of air this makes the draught that provides the ventilation where two mines are connected if the temperatures are the same in both mines the natural course of the draught would be downward through the shaft whose surface opening was the lowest in elevation and upward through the shaft whose surface opening was the highest however if the underground temperatures are different the shaft will naturally be the shaft of the hottest mine the reason for this lies in the fact that the air becomes hottest when it comes in contact with rocks of the greatest rock heat and becomes lighter by being more ramified rarified ra rifled and seeks its exit from the mine by rising through the nearest and most available passageway to the surface it is apparent that the air from the cooler workings will immediately rush into the hotter places to replace the air that passes out thus it may be that the highest shaft becomes the downcast down cast shaft in cutting openings between two mines the direction of the air currents can be determined by ascertaining the difference in elevation of two or more shafts and the difference in temperatures of the underground workings when workings have been cut together and have been or shut off by doors the direction of the air current should be posted on both sides of the door or bulkhead so that anyone opening the door or removing the bulkhead will know the direction that the air current is passing this is important in case of mine fires smoke fumes and gases may pass through the opening and suffocate unsuspecting workmen if proper attention is not paid to this matter again a fire upon one side of the bulkhead bulk head may be the cause of a reversal of the air current which should be carefully considered before removing bulkheads to fight mine fires natural ventilation may be provided even when it is impossible to connect with neighboring mines it is not new to suggest that a double compartment shaft be tightly lined between the two compartments thus providing an up cast and downcast down cast shaft in the same place one compartment or the other can be boxed and carried up to the top of the gallows frame if desired which will make one exit higher than the other this method makes excellent shaft ventilation regardless of the depth of the shaft mon as is this method of ventilating shafts shaft 8 without installing fans to cons consume lame pow power the principle is seldom carried into the lat 1 t eral workings of the mine A drift or crosscut on any level can easily be divided and lined just as the shaft was divided and lined it is not necessary that a crosscut be divided in the middle middie but a canvas or brattice can quickly be extended from the shaft to considerable distance away from it air coming down one compartment of the shaft can not get out except by passing into the mine and around the brattice and back to the opposite compartment part ment of the shaft in passing into the mine it becomes hotter the further it goes and the hotter the air coming out the stronger the draught this method of natural ventilation is extremely valuable where power costs are high and where underground connections cannot be made with neighboring properties it is generally more economical and more inore efficient than small fans beside saving the first cost of the fan and its motor or engine the labor of installation cost of foundations the cost of galvanized ventilating pipe the cost of labor installing pipes and the cost of pipe that is blaster and destroyed the larger volume of air with good natural ventilation allows better work by tho the workmen with less fatigue thus the cost per ton of ore produced is lowered by the increased tonnage produced by each man and the saving of power that would be necessary running the fan heat is power and the rock heat imparts an energy to the air that ventilates the mine accidents to pipe lines that are ventilated by fans have not only required expenditures for repairs but have caused a loss of much valuable time in remote parts of the mine assuming that the average employee in ia the metal mines of the west draws five anve cents ray nay for each six minutes of his time or fifty cents an hour a few idle hours a month for each man are expensive the conditions that surround each mine make it likely that the ventilation problems leing will have to be worked out in each individual case according to circumstances hut but out of 0 not the foregoing suggestions are place |