30 
BULLETIN 1179, U. S. DEPARTMENT OF AGRICULTURE. 
An inspection of Table 13 will show that samples Nos. 4-F, 4-T\ 
8-T. 9-T, 10-T, 11-T, 12-T, 13-T. and 16-T are so low in phosphoric 
acid as to eliminate them as commercial possibilities, unless they are 
reinforced with higher grade phosphates. But most of these samples 
(8-T to 13-T, inclusive) were taken from the waste pond of an old 
phosphate plant and represent the detritus washed out from run-of- 
mine material in preparing a high-grade rock for the market. It wilL 
also be noticed that in most instances where the phosphate content 
of the samples is low and the silica content high, there is sufficient 
clay present to admit of adding enough higher grade phosphate rock 
to obtain the proper silica-lime ratio without substantially reducing 
the binding qualities of the resultant mixture. 
In Table 14 are given the quantities of sand and coke which were 
added to 100 parts of the better grades of mine-run phosphate to make 
up charges suitable for furnace treatment. The composition of these 
briquetted charges is given in the last six columns of this same table. 
In Table 15 these same data are given for mixtures of two or more 
samples of mine-run phosphate, and the figures show how many low- 
grade deposits may be utilized by mixing the material with that from 
near-by or adjacent deposits of higher grade. 
Table 14. — Briquets suitable for furnace treatment formed by mixtures of natural 
phosphate rock, sand, and coke. 
Sample No. 
Briquet mixture 
Si0 2 :CaO=59:41. 
Calculated composition of briquet mixture (air-dried). 
Rock 
sample. 
Sand. 
Coke. 
Si0 2 - 
CaO. 
P 2 0.s. 
Fe 2 3 . 
AI2O3. 
Coke.i 
2 
Grams. 
100 
100 
100 
100 
100 
100 
100 
100 
100 
Grams. 
5.00 
14.85 
5.20 
10.27 
20.41 
28.91 
20. 85 
22. 91 
19.64 
Grams. 
14.32 
15.65 
14.35 
15.05 
16.40 
17.55 
16.47 
' 16.75 
16.30 
Per cent. 
31.67 
32.10 
35.79 
32.31 
32. 80 
32.70 
32.25 
32. 35 
32.00 
Per cent- 
22.18 
22.25 
24.84 
22.47 
22.80 
22.59 
22.40 
22.50 
22.23 
Per cent. 
17.96 
18.10 
18.00 
17.60 
17.62 
17.20 
16.54 
17.09 
16.75 
Per cent. 
2 9.87 
1.60 
23.29 
3.24 
3.00 
3.31 
3.80 
3.42 
3.35 
Per cent. 
Per cent* 
12.00 
1-F 
6.44 
12.00 
1-F(2) 
12.00 
3-T 
5.54 
4.75 
3.78 
5.39 
5.58 
6.18 
12. 00 
5-T 
12.00 
7-T 
12.00 
14-T 
12.00 
15-T 
12.00 
18-T 
12.00 
• 
1 The fixed carbon plus ash considered as coke. The coke used in these experiments contains 14.9 per 
cent of ash. An analysis of this ash showed that the coke in the briquetted mixture adds 0.98 per cent 
Si02, 0.02 per cent LaO, and 0.63 per cent Al 2 3 ,Fe 2 3 to the mix. 
2 Combined oxides of iron and aluminum. 
Table 15. — Briquets suitable for furnace treatment formed by mixtures of high-grade and 
low-grade phosphate rock with coke. 
Sample No. 
Briquet mixture 
Si0 2 : CaO = 59: 41. 
Calculated composition of briquet mixture (air-dried). 
Rock 
sample. 
Sand. 
Coke. 
Si0 2 . 
CaO. 
P 2 Oo. 
A1 2 3 . 
Fe 2 3 . 
Coke.i 
4-F 
Grams. 
44.4 
, 55. 6 
35. 43 
64.52 
44.7 
55. 3 
63.6 
Grams. 
} 
} 
} 
Grams. 
13.63 
13.63 
*3. 63 
13.63 
16.79 
Per cent. 
36. 01 
31.42 
31.50 
30.80 
33.00 
Per cent. 
24.01 
20.92 
21.90 
21.45 
22.95 
Per cent. 
17.00 
16.83 
16.95 
16.55 
Per cent. 
2 3.84 
3.80 
3.74 
4.25 
4.89 
Per cent. 
Per cent. 
1-F(2l 
5.00 
4.49 
6.68 
6.37 
3-T 
4-T 
12.00 
7-T 
8-T 
12.00 
15-T 
16-T 
36.4 \l 
33.33 
33.33 } 23.10 
33.33 1 
12.00 
18-T 
19-T 
12.00 
20-T 
1 The fixed carbon plus ash considered as coke. The coke used in these experiments contains 14.9 per 
cent of ash. An analysis of this as i showed that the coke in the briquetted mixture adds 0.98 per cent 
Si0 2 , 0.02 per cent CaO, and 0.63 per cent Al 2 3 ,Fe 2 3 to the mix. 
2Al 2 3 ,Fe 2 3 . 
