T H E JOIJRLVAL OF IiVDUSTRIAL AATD E-VGINEERING CHEMISTRY.
I08
The complete data for the year 1910, just available, a n average year, shows the following miscellaneous materials were sampled : Cars. 30.265 10.988
4,052 794 105 109
696 58 1,235
Material.
. ....... .
...
Coke ... . . . . . Coal . . . . . . . . , . . . . . . , , , . Limestone., . . . .. . . . . . . . . Refractories.. . . , . . , , , , Ferro-alloys., . . , , . . , , , , Fire-brick.. , . . . , . . . , , . , . , Scale and cinder.. , , , . . . Slags-various.. , . . . . , . , . . Miscellaneous., . , , . , , , .
..
.
48,302
.. .. . . . ..
Samples.
Weight of samples. Pounds.
3659 917 2107 378 105 113 264 3201 322
302,657 109,885 49,072 19,840 1,285 2,739 26,190 5,210 27,477
11,066
544,355
__
L A B O R A T O RSOUTH Y, WORKS, ILLINOIS STEELCo., December 3 1 , 1910.
NOTES AND CORRESPONDENCE. EFFICIENCY IN ACID PHOSPHATE MANUFACTURE. In even so simple a process as the manufacture of acid phosphate a high efficiency is not always attained. At the close of the spring season of 1908, a t this plant, the average insoluble phosphoric acid on the acid phosphate produced was 2 . j o per cent. and on the phosphate shipped was 1.74 per cent. About that time the writer was given charge of the acid phosphate manufacture, and since that time the same equipment has been producing acid phosphate with an insoluble of 0.75 to 1.00per cent. and shipping this product out with about 0.30 per cent. insoluble. This one change means an increase in efficiency of nearly $2 o , o o o . o o annually. A careful attention to details has brought about this result, but just what part of the change is due to each no one can tell. During the period mentioned, the change has been made from Tennessee to Florida rock, but the changes rcferred to and some of the results obtained were on Tennessee rock so that this change does not materiallyaffect the points in this paper. The more important details and the attention given them are as follows: Proportion 01 Acid aizd Rock.-The amount of acid required for the most efficient manufac'ture of acid phosphate can be determined only by trial for each kind and grade of rock. That quantity of acid which will give an insoluble phosphoric acid of 0 . 7 5 to 1 . 0 0 per cent. a t 48 to 7 2 hours old has proven best under our conditions. Strength of Acid.-Acid is used which when calculated to 6 o o F. will show 5 2 ' BC. Whether a formula calling for S I ! j z or 53 acid is used does not seem to be SO vital as the necessity of having a constant strength of acid to use after the formula has been decided upon. We do not allow the strength to vary more than 0.3' BB. either way from 5 2 ' when calculated t o 60'. Temperatwe of Acid.-In using the den system for acid phosphate manufacture the temperature of the acid does not seriously affect results, but in the single car open dump system the temperature must be above I O O O F. and should be 130' for good work. If this is not the case the reaction does not start in the
Feb., 1911
mixer promptly and a wet sloppy mixture is dumped on the pile which splatters so that i t never properly reacts. For efficient work with the open dump system the phosphate when dumped from the car must "set up," that is, must remain where it is dropped, not being liquid enough to run. The temperature of the acid is the most important factor in attaining this end. G,vade of Rock.-Diderent kinds of rock and even different grades of the same rock require different quantities of acid. It is therefore evident that economy demands keeping the different kinds and grades separate or, if this is not possible, using a definite and constant mixture. Unless excess acid phosphate storage room is available a loss will be experienced in the open dump system through the mixing of various grades of phosphate. Plant operation can be made more efficient therefore if one grade and kind of rock only is used. Fimwcss of Rock.-The results above cited have been obtained with rock ground until 9; to 97 per cent. pass a 60-mesh screen. 87 per cent. through the same screen will not give as good results and it seems doubtful if finer grinding would be more economical although some plants are operating on a finer rock dust. Time in the Mixer.--The remarks above on condition of the acid phosphate when dumped on the pile are to the point here. The charge of acid and rock must be held in the mixer until i t has reached a state that will give the required thick, pasty mass on the pile. The time required to do this will vary with the kind and fineness of the rock, the strength, quantity, and temperature of the acid but with these all properly regulated the. time will be between I and 3 minutes. Time i n the Pile.--As far as the operating conditions of the plant will allow, the acid phosphate should be allowed to lie in the pile and cure as long as possible, the limit being when the interest charges on the money invested exceed the increase in value due to lower insoluble and better mechanical condition. The reduction in insoluble is. of course, slow after three months have passed. When i t is known that the acid phosphate must be used up in a few days or weeks after i t is made, it is possible to use enough acid to reduce the insoluble to 0.40 per cent. by that time, but this may not be advisable because of the accompanying sacrifice Qf the mechanical condition. The proper course to pursue is a matter that must be left to the judgment of the man in charge. In conclusion, the key-note to efficiency in acid phosphate manufacture by the open dump system is an untiring watchfulness and attention to details. With the den system slightly less of this is demanded but the additional expense of one handling of the F. B. PORTER. acid phosphate is required. SWIPTFERTILIZER WORKS ATLAYT.4,
GA
LABORATORY DI5TILLATIONS OF WATER GAS TAR.
The information regarding the composition and properties of water gas tar available in books and
