IS BULLETIN 1179, IT. S. DEPARTMENT OF AGRICULTURE. 
Table 9. — Theoretical heat balance of electric furnace, shaft type. 
[Capacity 10 tons P2O5 per day of 24 hours.] 
Actions affecting temperature. 
Heat generated 
(plus). 
Heat consumed 
(minus). 
Item 
No. 
Thousands 
of 
kilogram - 
calories 
per ton 1 
Of P2O5. 
Per cent 
of total. 
Thousands 
of 
kilogram- 
calories 
per ton 1 
of P2O5. 
Per cent 
of total. 
1 
2 
3 
Absorbed by burden before fusion 2 
} : 
j 
4,100 
44.1 
4 
Evolved by exothermic reactions in ore. 
421) 
1,140 
2,660 
2,850 ■ 
4.5 
12.3 
6 
Evolved bv oxidation of this CO to CO2 
28.6 
30.6 
Evolved by oxidation of P2 to P2O5 
8 
2,369 
1.707 
1,124 
25.5 
9 
18.3 
10 
12.1 
11 
12 
»2,230 
24.0 
Total 
9,300 
100.0 
9,300 
100.0 
Economy: 6 
In pounds of P2O5 per kilowatt hour 0. 85 
In 2,000 pounds P2O5 per kilowatt year '. . 3. 70 
In 2,000 pounds P 2 5 per horsepower year 2. 77 
In over-all thermal efficiency, per cent 44. 10 
1 Metric ton. 
2 Included in item 9. 
3 Including small amount of f errophosphorus. 
* Assuming all CO burned in furnace crucible and shaft. 
s 2,595 kilowatt hours. 
« Production based on 90 per cent recovery of P20» in furnace charge. 
It will be noted that under these conditions the over-all furnace 
reactions are exothermic. If, therefore, no heat were lost in the 
evolved gases, in unburned carbon monoxide, from radiation through 
the walls of the furnace, and in the slag which is tapped off, the 
reaction when started should go to an end without power consump- 
tion. Of course, some of these losses can not be avoided and others 
can only be partially eliminated, but as will be seen by comparing 
the figures for the two types of furnaces the efficiency of the shaft 
type, wherein much of the heat in the effluent gases is conserved and 
the phosphorus and CO are completely oxidized *bef ore leaving the 
furnace shaft, a great saving in power consumption may be effected. 
With the development of certain power sites it is possible that elec- 
tric energy may be obtained for purposes such as fertilizer production 
at a price much below $25 per horsepower year. This would make it 
feasible either to transport and use higher grade phosphate rock 
from the Florida fields or to transmit such power to the Tennessee 
phosphate fields and use run-of-mine phospnates, thus eliminating 
the costly washing process and conserving and utilizing deposits 
which are at present considered unfit for the production of phos- 
phatic fertilizers. The map (fig. 6) graphically illustrates the distance 
between Muscle Shoals and the phosphate deposits of Tennessee. 
