94 GASES FROM CERTAIN EXPLOSIVES. 



Although the explosive alone contained a slight excess of 

 oxygen it did not contain enough to oxidise all the carbon- 

 aceous matter of the wrapper; hence the partial oxidation and 

 consequent production of carbon monoxide. This discovery, 

 which looks small and unimportant, led to the introduction of 

 a new class of explosive, which has been a great boon to miners 

 who have to work in places where the ventilation is bad. 

 Some people still believe that oxidising mixtures, " outwith " 

 the explosives for which there are many patents, prevent the 

 formation of noxious gases such as carbon monoxide, but the 

 results which I have obtained show that they have no influence 

 one way or another. 



At the close of my last paper on this subject I ventured to 

 say : — 



" That to my mind the removal of carbon monoxide by efficient means of 

 ventilation is the most pressing problem which Rand Mining Engineers 

 have to face and once its importance is realised and effective measures are 

 taken to deal with it the health of the miners will be greatly improved." 



I am glad to record that these semi-prophetic words have 

 borne fruit. A start has been made, and one or two mines, 

 but notably those of the East Rand Proprietary Mines, 

 are now thoroughly well ventilated. This particular 

 group first of all had the mine gases thoroughly 

 examined — a gas analysis survey was made. Those 

 places at which the ventilation, as indicated by the 

 results, was bad, were carefully noted and special steps were 

 taken to increase the supply of fresh air at these points. 



It does not come within the scope of this paper to describe 

 the system of ventilation adopted, but that it has done all that 

 was expected can be shown by the following quotation : — 



" Samples- were taken from the bottom of three shafts, viz., the Farrar, 

 No. I shaft (Driefontein), and the main shaft (Angelo). In all these shafts 

 sinking was proceeding. The average results for these points were as 

 follows : — 



CO, = 0.552 % 



CO = 0.011% 



" After the ventilation scheme was in operation samples were again taken 

 from these points, and the following average results obtained : — 



CO, = 0.149 % 

 CO = 0.006 % 



" It will be noted that these figures do not represent the average for the 

 mine. The average figures for the mine, however, were : — 



First. — before the adoption of the ventilation scheme : — 



CO, = 0-493 % 



CO = 0-0I2 % 



Second. — After the adoption of the ventilation scheme : — 

 CO,, = 0-127 % 

 CO" = 0-005 % 



' Recent samples taken from the air drift at the Angelo upcast directly 

 after blasting, when the vitiation of the air should be at its worst, gave the 

 following results : CO^ = 0-182 % and CO = o-ooi % The temperatures 

 have been reduced by from 2° to 3°. 



" The capital expenditure on the installation for the whole property, 

 including fans and motors, erection of same, equipment of up-cast shafts, 

 bratticing, doors, pipes, etc., was about ;^25,ooo. 



