IX, A, 3 Dalburg and Pratt: Iron Ores of Bulacan 



Table V. — Statistics of iron smelting in 1913. 



NUMBER, WEIGHT, AND VALUE OF PAIRS PRODUCED. 



249 





Pairs. 



Tons. 



Value. 



First class -- - 



12,440 



9,147 



13,006 



22,783 



40.4 



36.6 



36.0 



113.7 



!>13, 684 

 13, 720 

 12,006 

 25,061 



Second class _ _____ 



Third class _ 



Points _ _ 



Total _ 



56,376 



226.7 



64,471 





Furnaces in blast 10 



Smelting runs (cendidas), all furnaces 61 



Days in blast, all furnaces 657 



Ore used tons.... 555 



Calculated weight of iron in ore " _ do 333 



Charcoal used _ _ do 960 



Average length of furnace run , days.... 11 



Days in blast (average for each furnace for the year) 65 



Pairs per day in blast (average) 86 



Iron per day in blast (average) kilos... 345 



Ore required per ton of iron smelted tons .... 2.45 



Charcoal used per ton of iron smelted _ do 4.23 



Efficiency of Filipino process, per cent extraction 68 



Value of product per ton _ _ P284.00 



^ Metallic iron assumed to constitute 60 per cent of ore. 



About 68 per cent of the iron in the ore is extracted by the 

 process. The loss of iron is not due, however, to the production 

 of a ferrous slag but, as will be shown presently, to the carrying 

 off of pellets of iron and pieces of unreduced ore which are 

 mechanically inclosed in the slag. 



Metallurgy of the smelting process. — The cast iron produced 

 in Bulacan is uniformly a white fine-grained iron which is low 

 in silicon, contains very little graphitic carbon, and is extra- 

 ordinarily hard. Due probably to its hardness, the iron is very 

 satisfactory in the use to which it is put and the implements 

 made from it are much preferred by the farmer to those made 

 from imported pig iron. The properties of the iron can be 

 explained by the low temperature at which it is reduced and 

 cast and the rapidity with which the castings cool. Analyses 

 of the product appear in the following table. Sample 13a is 

 an unusual iron produced in the Hison smelter and cast at the 

 end of an unsuccessful run of three days; the difficulty in this 

 run was explained by the maestro as due to the presence of 

 quartzose ore (bacal sigay) in the charges. Sample 99 is the 

 typical Hison iron, and sample 100 is the usual Montamorong 

 product. 



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