Mance: Quarry Industry of Southern Indiana 



87 



tion of mechanical draft this objection disappears since high 

 enough draft pressures can be produced with mechanical draft. 



Coal handling in the quarry belt is carried on in a very waste- 

 ful manner. The power plants of a few of the larger mills are 

 equipped with stokers, but in general hand-firing is practiced. 

 In many of the smaller plants no switch arrangements have been 

 made to bring the coal as near as possible to the boiler plant, 

 and much hand-shoveling and wheelbarrow work is necessary. 

 Of course, with the modern steam quarry machinery this extra 

 handling is necessar}^, since it would be impossible to deliver the 

 coal directly to the units using it. In figuring the relative cost 

 of electrical and steam equipment, few of the operators take into 

 account the losses resulting from the present methods of handling 

 coal. Coal is brought to the quarry or small mill and clumped 

 in carload heaps. The loss in heating value of coal stored in 

 this way represents a noticeable percentage of its heat value. 

 In addition to this, much of the coal is scattered and lost. I have 

 seen quarries where the entire surface of the quarry opening was 

 covered to a greater or less extent with fine coal. The savhig in 

 this regard alone would represent 1 per cent of the power cost for 

 steam channelers, not to mention the saving in the cleanliness 

 of the stone. A fair figure for the saving in cost of labor and fuel 

 that could be realized in a quarry running 4 channelers, a stripping 

 pump, and 2 derricks, if motors were used instead of steam units, 

 would be 10 per cent of the power cost. 



As the size of power plants increases, the saving in the use 

 of coal and ash handling machinery becomes more apparent, and 

 after the size of the boiler equipment passes 500 horse-power, 

 hand-handling of the coal is out of the question. 



So much has been written on the selection of a suitable engine 

 for almost every line of work that no attempt will be made here to 

 discuss the relative values of the different types. So many factors 

 enter into the selection of an engine that no two operators have the 

 same conditions on which to figure. The factor of first cost is 

 usually the determining one, and in many cases the only one that 

 • counts. In all cases where it is possible, the factor of cost per 

 horse-power used should determine the choice. Engine building 

 has developed until the steam consumption of any given type of 

 engine is the same, regardless of what company builds it. The 

 following table from Meyer's Steam Power Plants (p. 49), shows 

 the steam consumption of the various types of steam engines: 



