I n d . Eng. Chem. Res. 1988,27,857-865
was found to be essentially equivalent in effectiveness to that of ammonium nitrate, while the citrate-soluble P205 contents were found to be equivalent to that of triple superphosphate. Small-scale Pilot-Plant Experience. The 27-9-0 grade product (HN03:Ca0 = 2, urea:CaO = 3.3, Table IX) has been successfully granulated in a small-scale pilot plant. The granule hardness was about 3 lb (1.4 kg) as produced but increased to 4 Ib upon aging for 60 days. The loose pour density was 45 lb/ft3 (720 kg/m3), and the apparent specific density of the individual granules was 1.45 g/cm3. The angle of response was 40 deg. Moisture penetration tests indicate that the 27-9-0 grade product is slightly less susceptible to moisture penetration than a conventional 20-20-0 grade nitric phosphate. Flow properties of the product under high humidity are not quite as good as for conventional nitric phosphate but are much better than for ammonium nitrate. Bag storage tests appear promising, particularly for those products with moisture contents below 1% . Flame penetration and impact tests suggest that the product is nonexplosive. The other products listed in Table IX have not yet been granulated. As indicated in Table IX, the treatment of phosphate rock simply with nitric acid and urea results in products with grade ratios ranging from 2-1-0 to 3-1-0. The following paper in this issue will describe the properties of other grade ratio urea-nitric phosphate products which may be prepared by incorporating wet-process phosphoric
857
acid into the processing scheme. Registry NO. N, 113086-60-5; U, 57-13-6; P, 7723-14-0;CaNU, 56750-36-8; CaUP, 22697-15-0; UN, 124-47-0; UP, 4861-19-2; Ca(N03)*,10124-37-5; Ca(H2P0J2,7758-23-8; hydroxy apatite, 1306-06-5.
Literature Cited Adams, J. R.; Merz, A. R. Ind. Eng. Chem. 1929, 21(4), 305-307. Frazier, A. W.; Lehr, J. R.; Smith, J. P. J. Agric. Food Chem. 1967, 15(2), 345-347. Grundt, T.; Heggebo, T. "ProductionCost of Nitrophosphate Type Complex Fertilizers. A Comparison to the Sulphur Based Route". Presented at the 188th National Meeting of the American Chemical Society, New York, July 25,1984, Fertilizer and Soils Division. Guillet, R.; Cluzel, J. French Patent 1 107 730, Jan 4, 1956. Guillet, R.; Cluzel, J.; Giraud, R. French Patent 1 182 058, June 22, 1959. Kochemba, Yu. I.; Shenkin, Ya. S. Zh. Prikl. Khim. 1982, 55(5), 977-980. Nagai, S.; Kanazawa, T. J . Chem. SOC.Jpn., Ind. Chem. Sect. 1951, 54(3), 39-41. Nagai, S.; Kanazawa, T.; Saito, K. J. Chem. SOC.Jpn., Ind. Chem. Sect. 1951a, 54(3), 8-11. Nagai, S.; Kanazawa, T.; Sakurada, K. J. Chem. SOC. Jpn., Ind. Chem. Sect. 1951b, 54(10), 612-615. Shenkin, Ya. S.; Klevke, V. A. Khim. Prom-st. 1964, I , 57-61. Shenkin, Ya. S.; Klevke, V. A.; Lyudkovskaya, B. G. Dokl. Akad. Nauk SSSR 1963,149,656-659. Slack, A. V.; Blouin, G. M.; Livingston, 0. W., "It's Time to Consider Nitric Phosphates". TVA Reprint No. CD-456, 1967.
Received for review March 13, 1987 Accepted November 10, 1987
Physicochemical Properties of New Solid Urea-Nitric Phosphate Fertilizers. 2. Products from Nitric Acid, Phosphate Rock, Urea, and Supplemental Wet-Process Phosphoric Acid Jack M.Sullivan,* John H.Grinstead, Jr., Yong K. Kim, and Kjell R. Waerstad Division of Research, National Fertilizer Development Center, Tennessee Valley Authority, Muscle Shoals, Alabama 35660
Statistically designed experiments were conducted to determine the physicochemical properties of solid urea-nitric phosphate products prepared by reacting phosphate rock with nitric acid, wet-process phosphoric acid, and urea. The composition variables were adjusted to produce 1-2-0,l-1-0, and 2-1-0 grade ratio fertilizers. T h e optimum 1-2-0 product was of grade 13.6-28.1-0, with an ammonium citrate Pz05solubility of 98.9% and a critical relative humidity of 54.7%. The optimum 1-1-0 product was of grade 18.5-19.3-0, with an ammonium citrate Pz05solubility of 99.0% and a critical relative humidity of 57.4%. The optimum 2-1-0 product was of grade 23.9-12.3-0, with an ammonium citrate Pz05 solubility of 98.4% and a critical relative humidity of 58.7%. The physical and chemical properties of other products also are described.
In the previous paper of this series (Sullivan et al., 19881, we described the properties of solid urea-nitric phosphate fertilizers which may be prepared by reaction of phosphate rock with nitric acid and urea. The grade ratios of these products ranged from 2-1-0 to 3-1-0. The 2-1-0 grade products generally were prepared at lower nitric acid acidulation ratios and hence contained lower contents of water- and citrate-soluble P205than did the 3-1-0 grade products. To obtain further grade variations and to ensure high water- and citrate-soluble Pz06contents, it is necessary to incorporate wet-process phosphoric acid (WPA) into the acidulation scheme. Of course, under these con-( ditions the process loses some of its independence from This article not subject to
sulfuric acid and some of its advantage of using the cheapest source of phosphate (phosphate rock). In this report, we describe the results of factorially designed experiments to determine the optimum physical and chemical properties of 1-2-0,l-1-0, and 2-1-0 grade ratio urea-nitric phosphate products which may be prepared by incorporating WPA into the acidulation step. Experimental Section The procedures for characterizing the individual products were described in the previous publication (Sullivan et al., 1988). The phosphate rock was of central Florida origin and had the following composition: 30.4% P205,
U.S.Copyright. Published 1988 by the American Chemical Society
858 Ind. Eng. Chem. Res., Vol. 27, No. 5, 1988 Table I. Ranges of Composition Variables and Experimental Results for Production of Approximately 1-2-0 Solid Urea-Nitric Phosphate Fertilizers level coded variable, M/M -2 -1 0 1 2 CaO:HN03 ( X , ) 0.70 0.80 0.90 1.00 1.10 1.12 1.24 1.36 PO,:HN03 ( X , ) 0.88 1.00 0.88 0.98 1.08 1.18 1.28 urea:HN03 ( X 3 ) mole ratio P206solubility, % expt CaO:HN03 (X,)P0,:HN03 ( X , ) urea:HN03 (X,) exptl grade water-soluble citrate-soluble CRH at 25 "C, '70 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
0.80 1.00 0.80 1.00 0.80 1.00 0.80 1.00 0.70 1.10 0.90 0.90 0.90 0.90 0.90 0.90 0.90
(-1) (1) (-1) (1) (-1) (1) (-1) (1) (-2) (2)
(0) (0)
(0) (0)
(0) (0) (0)
1.00 1.00 1.24 1.24 1.00 1.00 1.24 1.24 1.12 1.12 0.88 1.36 1.12 1.12 1.12 1.12 1.12
(-1) (-1) (1) (1) (-1) (-1) (1) (1) (0) (0) (-2) (2) (0) (0) (0) (0) (0)
0.98 0.98 0.98 0.98 1.18 1.18 1.18 1.18 1.08 1.08 1.08 1.08 0.88 1.28 1.08 1.08 1.08
(-1) (-1) (-1) (-1) (1) (1) (1) (1)
(0) (0) (0) (0) (-2) (2)
(0) (0) (0)
45.2% CaO, 1.21% A1203, 1.34% Fe203,0.37% MgO, 8.8% SO2, 3.63% F, 0.09% KzO, 0.66% Na20, 0.007% C1, 125 ppm of U, 96 ppm of V, 61 ppm of Cr, 830 ppm of Ti, and 3.4% total carbon. The rock was ground to 55.8% -200 mesh. The WPA also was of central Florida origin and gave the following analysis: 54.9% P205,0.55% F, 3.7% SO3,0.002% CaO, 0.53% MgO, 1.8% A1203,1.4% Fe203,
