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.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
ammonium citrate solution is reduced by the presence of calcium sulfate, which is soluble in citrate solution, 3-As determined by the official method of analysis, the citrate solubility of water-insoluble phosphates depends on the type and quantity of phosphate compound, or compounds,. present. 4-Citrate-insoluble residues obtained from ammoniated and non-ammoniated superphosphates and triple superphosphates contain varying quantities of iron, aluminum, calcium, phosphoric acid, and fluorine, but little or no sulfate. &In general, treatment of superphosphates and triple superphosphates with relatively large quantities of ammonia tends to decrease the solubility of the iron in neutral ammonium citrate solution, has little, if any, effect on the solubility of the aluminum, and greatly reduces the solubility of the calcium and phosphoric acid. 6-Citrate-insoluble residues obtained by the large-scale extraction of processed phosphate materials contain varying and, in general, significant quantities of citrate-soluble phosphoric acid as determined by a second treatment with citrate solution. 7-Citrate-insoluble residues obtained from tricalcium phosphate consist wholly, or in part, of calcium hydroxyphosphate, which is less soluble than the original tricalcium phosphate in citrate solution. 8-Citrate-insoluble residues obtained from ammoniated and non-ammoniated superphosphates and triple superphosphates contain iron and aluminum phosphates and unattacked phosphate rock. I n addition to these compounds, residues obtained from highly ammoniated ordinary superphosphates, extracted in the proportion of 2 grams to 100 cc.
Vol. 22, No. 12
of citrate solution, contain tricalcium phosphate, calcium hydroxyphosphate and, perhaps, some dicalcium phosphate, but when these materials are extracted in the proportion of 0.5 gram to 100 cc. tricalcium phosphate either is absent or is present only in relatively small quantities. Dicalcium phosphate is the principal phosphate compound present in residues obtained by extracting ammoniated triple superphosphate in the proportion of 2 grams to 100 cc. of citrate solution. Acknowledgment
The writers are indebted to F. G. Keenen, of the Du Pont Ammonia Corporation, and to C. C. Howes, of the Davison Chemical Company, for the majority of the samples of phosphates used in this investigation. Grateful acknowledgment is made to K. C. Beeson, H. L. Marshall, and D. S. Reynolds for their very valuable assistance in the preparation and analysis of the citrate-insoluble residues and the analysis of the original materials. Literature Cited (1) Assocn. Official Agr. Chem., Xethods, p. 4 (1925). (2) Austin, IND. END.CHEM.,16, 1037 (1923). (3) Carter, Ibid., 22, 886 (1930). (4) Haskins, J. Assocn. Oficiol Agr. Chem., 4,64 (1920); 5, 97 (1921). ( 5 ) Hawley, IND. END. CHBM.,18, 573 (1926). (6) Hoffman and Lundell, Bur. Sfondords J. Research, 3, 581 (1929). (7) Jacob, Hill, and Holmes, Colloid Symposium Annual, Vol. VII, p. 195 (1930). (8) Lorah, Tartar, and Wood, J. A m . Chem. Soc., 61,1097 (1929). (9) Reynolds, Ross, a n d Jacob, J. Assocn. Oficial Agr. Chem., 11, 225 (1928). (10) Thomas, J. IND.E N D .CHEM.,9,865 (1917). (11) Warrington, J . Chem. SOC.,19, 296 (1866); ‘26, 983 (1873).
Chemical and Physical Composition of Certain Finely Divided Natural Phosphates from Florida’ W. L.
K. D. Jacob,*L. T. A l e ~ a n d e rand , ~ H. L. Marshall2 BUREAUOF CHEMISTRY AND SOILS, WASHINGTON, D. C.
A study has been made of the chemical and physical verted into new p o n d s . composition of several samples of natural soft and wasteThese “waste-pond” phosthe Florida hard-rock pond phosphates from Florida. The results given in phates, which usually vary in p h o s p h a t e industry, the present paper include data on the physical composhade from white to a straw attention was called to the sition of the samples, effect of temperature on the color, are composed of very soft chalky phosphates (3, 9, physical composition, specific gravity, chemical compofine particles and when wet 10) which occur in considersition of the original phosphates and the mechanical they are quite plastic and able quantities, not only in fractions separated therefrom, and the solubility of the sticky. Upon drying they close association with the phosphoric acid in neutral ammonium citrate and 2 s h r i n k a n d c r a c k in the hard-rock phosphate, but also per cent citric acid solutions. manner c h a r a c t e r i s t i c of in individual deDosits of varimaterials c o n t a i n i n g high able size. Mitson (6) has discussed these phosphates with particular reference to their percentages of colloid. The air-dried lumps, which disdistribution in the Florida hard-rock and land-pebble districts. integrate rapidly when placed in water, usually contain During the process of preparing Florida hard-rock phos- about 18 to 25 per cent phosphoric acid (P205)and 15 to 18 phate for the market the soft phosphate present in the matrix per cent iron and aluminum oxides. The abandoned waste is washed into waste ponds, where it settles out along with ponds in the Florida hard-rock district are estimated to conthe clay and other impurities, the finer particles concentrating tain several million tons of this material. I n this paper the a t points farthest from the entrance to the pond. When fine phosphate deposited in the Florida hard-rock phosphate the ponds become filled with waste material they are allowed waste ponds will be called “waste-pond” phosphate in order to to dry up and the water from the phosphate washers is di- distinguish it from the soft phosphate obtained directly from the natural deposits. 1 Received September 22, 1930. Presented by W. L. Hill, L. T. Owing, in general, to the relatively low content of phosAlexander, and K. D. Jacob before the Division of Fertilizer Chemistry a t the 80th Meeting of the American Chemical Society, Cincinnati, Ohio, Septemphate and high content of iron and aluminum, it has not been ber 8 to 12,1930, considered practicable to attempt the conversion of soft 2 Fertilizer Materials and Manufacture Division, Bureau of Chemistry phosphate into superphosphate by treatment with sulfuric and Soils. or other acids. Waggaman (8) and Matson (6) have sug8 Soil Chemistry and Physics Division, Bureau of Chemistry a n d Soils
E
ARLY in the history of
INDUSTRIAL AND ENGINEERIA’G CHEJIISTRY
December, 1930
gested, however, that because of the fineness of the particles it should be a valuable phosphate fertilizer material for direct application to certain types of soil. dccording to Wright (9) in the early years (1890-92) of the Florida phosphate industry from 2000 to 11,000 tons of soft phosphate were used annually for this purpose. Since that time the annual production of soft phosphate has fluctuated considerably and probably has not exceeded 15,000 long tons. During the past few years interest in the finely divided natural phosphates, particularly the waste-pond phosphate, has been revived not only as regards their direct use as fertilizer, but also in connection with their utilization in certain industrial processes and products requiring the use of finely divided materials of a more or less collodial nature.
’”
other samples varied from white to straw color. All these samples represented material that had been deposited a t some distance from the point where the water from the phosphate washers entered the waste ponds. Physical Composition
I n order to obtain information on the physical composition of the phosphates, four samples of soft phosphate and nine of waste-pond phosphate were analyzed by the pipet method as modified by Alexander and Jacob (1) for the mechanical analysis of finely divided natural phosphates. The lump samples were crushed to pass a 10-mesh sieve while the ground samples were analyzed without further treatment. Grinding during the crushing operation was avoided as much as possible, in order not to break up hard particles that might otherwise fail to disintegrate under the action of water and dispersing agents alone. The Florida hard-rock phosphate, which is included for comparison, was prepared by grinding a sample of high-grade commercial material to pass a 100-mesh sieve having openings 0.147 mm. square. The mechanical separations were effected into seven fractions having the range of particle size customarily used in the mechanical analysis of soils in the United Statesnamely, (1) particles 2000 to lOOOp, (2) 1000 to 5OOp, (3) 500 to 250p, (4)250 to lOOp, ( 5 ) 100 to 50p, (6) 50 to 5pJ and (7) less than 5p in diameter. The percentages of particles finer than 2p in diameter were also determined. Following the terminology used in soil analysis, fractions 1 to 5, comprising particles 2000 to 50p in diameter, mill be designated as “sand,” fraction 6 as “silt,” and fraction 7 as “clay.” It should be noted, however, that these terms are used in the present paper only for the sake of convenience, and do not imply that the chemical composition of the material is similar to that of soil.
~ r nWaste -pondphospha$ ho 727
z o j E : g So“p phosphate 00 8
Hard rockphospha’e
No 932
IO
0 1 0147 0 2 5 of particles in m m
00s
Diameter
050
LO
Figure 1-Particle-Size Distribution Curves Obtained by Plotting Percentages of Material Finer t h a n a Given Size a g a i n s t the Logarithm of t h e Diameters of t h e Particles
As a part of an investigation relating to the utilization of the finely divided natural phosphates of Florida, a study was made of the chemical and physical composition and properties of several samples of these materials. The results of this study are given in the present paper. Materials Used
SOFTPHosPHATE-Samples 443 and 728 were obtained from natural deposits located, respectively, in Gilchrist County and near Juliette in Marion County. Sample 580 was obtained from a deposit, the location of which is unknown, in the hard-rock phosphate district. Except for air-drying, these samples were in the natural condition as taken from the deposits. Sample 1091 was a commercial material mined near Bartow, Polk County, in the pebble phosphate district. It had been kiln-dried and ground to about 75 per cent through a 200-mesh sieve. WASTE-POND PHOSPHATE-A~~ the samples of waste-pond phosphate were obtained from abandoned hard-rock phosphate waste ponds near Dunnellon, Marion County, and Hernando, Citrus County. Sample 824 was received in the air-dry condition. Samples 825 and 915 had been kilndried and coarsely ground for commercial purposes. The other samples were received in the wet condition just as taken from the deposits. They were dried a t temperatures below 90” C. Sample 826 was slate-colored, while the
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Table I-Physical
I SAMPLE
1
Waste-pond DhosDhate . 725 726 727 824 825 826 827 828 915 Soft DhoS- I phate
Hard-rock phosphatea 932 a
I
Composition of Florida Phosphates
1
“SAND” 2000- 10001000s 500s
0.0 0.0 0.0 0.0 0.0 0.0 0.0
500- 250- 100250s 100s 50s
0.0 0.0 0.1 0.0 0.1 0.1 0.0 0.0 0.1
0.0
0.0 0.0 0.2
0.1 0.2 0.2 1.4 1.1 0.4 0.1 0.1 0.8
0.2 0.2 0.2 0.6 0.8 0.4 0.1
4.5 22.8 2.1 6.2 6.9 9.7 0.0 0.8
6.3 7.6 4.5 1.9
11.3 19.8 7.4 8.7
7.2 4.3 4.0 8.7
0 0
0 0
10 7
22.5
0.0 0.1
0 0
0.0 0.1
0.2 0.2 0.1
I
1-1
50-5s
I
1
15.9 11.7
10.0
0.0 0.5
“SILT”
1
I
1
15.9 15.9 19.5 9.0 12.8 14.0
I
18.7 1;:: 23.0 43.9
~
I
“CLAY”
