Pilot plant development of a fertilizer process in which rock phosphate is acidulated with nitric and phosphoric acids is described. The process, technical feasibility of which was demonstrated through operation of a 4-ton-perday pilot plant, involves acidulating rock with mixed acids [mole ratio (HNOa •+ H3P04)/CaO = 2.1 and Ca0/P205 = 2.0], ammonia ting the resultant solution to pH 3.7 to 4.0, drying, and granulating. Introduction of potassium chloride into the molten product from the dryer is optional to produce an N-P2O5-K2O fertilizer.The proportions of N-P2O5-K2O in the product are variant; compositions prepared include 12-33-0, 19-19-0, 11-22-11, and 15-18-10. A FUNDAMENTAL advantage of the use of nitric acid for decomposing rock phosphate in the manufacture of fertilizers is that the cost of the acid is offset by the value of the nitrogen in the fertilizer product. Furthermore, the requirement for-and the expense of-sulfuric acid, fuel, or electrical energy used for decomposing rock phosphate in other processes is eliminated or decreased, the products are more concentrated than the usual

Interactions between effects of undernutrition and weaning on the duration of post-partum anoestrus and associated variation in milk yield, suckling behaviour, and metabolic hormone levels in Droughtmaster [Bos indicus x Bos taurus (518, 3/8)] first-calf cows were studied in 2 successive years. Low body condition score at calving (3.5f 0.1, scale 1-9) was associated with prolonged post-partum anoestrous intervals in suckled cows, but provided cows were maintaining liveweight, ovarian cyclicity resumed within 50 days if calves were weaned 70 days post-partum. This response to weaning was totally inhibited in cows that calved in low body condition that lost liveweight post-partum (Year 1). In contrast, marked levels of post-partum liveweight loss (23%) did not affect resumption of ovarian cyclicity in response to weaning (at 50 days post-parturn), or time to conception, among cows that calved with high body condition scores (5.8 � 0.2, Year 2). Reduced milk yields and calf weight gains among underfed cows were associated with higher suckling frequencies and durations ( P < 0.05). Acyclic interval after weaning was negatively related to body condition score at weaning (P < 0.01), and positively related to preweaning suckling intensity (P < 0.01). The time taken to resume ovarian cyclicity after weaning increased by a factor of 1.2 for every half unit decrease in body condition score at weaning, and by a factor of 1.3 for every 30-min increase in time suckled per day prior to weaning. Within level of nutrition, higher frequencies and durations of suckling were associated with higher plasma prolactin levels. Plasma IGF-1 levels were consistently depressed in underfed cows, whereas plasma insulin and GH levels were less affected by nutritional treatments. Effects of undernutrition in suckled cows appear to operate at least partly through interactions with milk yield and suckling intensity. Management of post-partum anoestrus in Bos indicus cows should focus on the conservation of cow body condition and on the strategic use of early weaning.

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ILOT plant production of ammonium nitrate by continuous vacuum crystallization has been described by Miller and Sae-P man (3). Their work led to the construction of a 525-ton-perday vacuum crystallizer plant by the Tennessee Valley Authority at Wilson Dam, Ala., to provide a safer and more economical process than the graining process that had been in use. Operation of the plant was tested on a limited production basis in 1949, and full scale operation was started in 1950, at which time graining operations were discontinued. This paper describes the plant, which is the fist of its kind to utilize continuous vacuum crystallization for large scale production of ammonium nitrate, A flow diagram of the plant is given in Figure 1. The steps in the operation of the plant are: neutralization of nitric acid with ammonia, purification and concentration of the ammonium nitrate solution, cryst,allization, and drying and bagging of the product. A.I.S.I. Type 430 stainless steel is the standard material of construction throughout the plant.All the equipment, with the exception of the settling tanks and the storage tank, is housed. A cross-sectional view of the building is shown in Figure 2. The portion of the building that houses the crystallizers is insulated and is maintained at a temperature of about 105 O F., or slightly above crystallizer temperature. Routine control of the crystallizers is maintained from a central control room kept at normal working temperatures. NeutralizationReaction of nitric acid with anhydrous ammonia, both of which are produced at Wilson Dam by TVA, is carried out in four neutralizers operated in parallel.Each neutralizer consists of a covered, cylindrical tank 10 feet in diameter and 10 feet high. Ammonia gas enters near the bottom through a "wagon-wheel'' sparger, and 42.5% nitric acid enters just above the ammonia. The rate a t which the acid is fed to the system is adjusted manually, and the rate a t which the ammonia , E i n t F d l r c , = r l i a roriilated NEUTRALIZER tion to 6.4 through automatic control described by Harvey and Ewald (1). The heat of reaction maintains the solution a t boiling in the neutralizers, and the result is the evaporation of about 605 pounds of water per ton of ammonium nitrate in the solution. The ammonium nitrate solution at this point in the process contains about 56% IVHJK-03. Two-stage instead of single-stage neutralization is used because the latter results in unstable automatic control and in a significant loss of ammonia. The neutralizers operate a t atmospheric pressure and are protected by water seals against overpressure or vacuum. Ammonium nitrate entrained in the neutralizer vapor and the liberated heat are recovered in the concentration step of the process.PurificationThe neutralized solution contains about 0.03% of precipitated hydroxides of iron and aluminum, which, if allowed to accumulate, would adversely affect the crystallization of ammonium nitrate, The impurities are separated from the solution as a sludge, which collects in the settling tan...

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