Abstract: An improved fluid urea-containing fertilizer composition is disclosed; the composition is essentially comprised of an aqueous solution of urea, ammonium nitrate, N-(n-butyl)thiophosphoric triamide (NBPT), dicyandiamide (DCD), and may optionally also contain a clay as a suspending agent. The fluid fertilizer composition can be applied to a field crop in a single application and will nevertheless supply sufficient nitrogen to the plants throughout their growth and maturing cycles. As a result, the improved composition increases the nitrogen uptake efficiency of plants, enhances crop yields, and minimizes the loss of nitrogen from the soil.

Abstract: An improved homogenous granular fertilizer composition is disclosed; the composition is comprised primarily of urea, N-(n-butyl)thiophosphoric triamide (NBPT), and dicyandiamide (DCD). The composition of this invention can be applied to a field crop in a single surface application and will nevertheless supply sufficient nitrogen to the plants throughout their growth and maturing cycles. The new improved composition increases the nitrogen uptake by plants, enhances crop yields, and minimizes the loss of both ammonium nitrogen and nitrate nitrogen from the soil.The NBPT is incorporated into the homogenous granular fertilizer composition of this invention by blending a concentrated solution of NBPT in a solvent selected from the group consisting of liquid amides, 2-pyrrolidone, and N-alkyl 2-pyrrolidones directly into molten urea prior to its granulation; the DCD may be added to the urea melt as a solid or in dissolved form along with the NBPT.

Abstract: Stabilized phosphogypsum-containing compositions with low expansion and high compressive strength characteristics are prepared by admixing phosphogypsum with a cementitious binder having a calculated zero percent tricalcium aluminate content The compositions may contain phosphogypsum and cementitious binder only or they may also include sand or other filler material. The phosphogypsum composition is wetted with water, compacted and allowed to cure. The amount of water added preferably produces a maximum density of the compacted composition.

Abstract: This invention provides a method for removing aluminum contamination from phosphoric acid during the acidulation of phosphate rock with sulfuric acid in the presence of recycled phosphoric acid. The method of this invention involves the addition of acid soluble silica to the acidulation slurry and calls for maintaining the molar ratio of non-fluosilicate fluoride (i.e. fluoride not complexed with silica) to aluminum in the liquid phase of the acidulation slurry between 2.5 and 5.0. These conditions favor the precipitation of aluminum as calcium tetrafluoaluminate dihydrate and enable the co-removal of this compound by filtration with by-product gypsum. This invention is particularily suitable for the processing of phosphate rocks with high iron and aluminum contents, such as the nonsedimentary phosphate rocks occurring in Sri Lanka.

Abstract: This invention provides an improved method for the rougher flotation of phosphate ore using sodium carbonate to control the pH at about 9.6-10.5. The method facilitates improved recovery of phosphate from its ore; in addition the Bone Phosphate of Lime (BPL) of the phosphate concentrate increases, which provides further advantages in that subsequent steps are improved by virtue of receiving a feed of greater purity. There are also certain environmental advantages obtained when ammonia is replaced with sodium carbonate and the operational safety of the flotation system is enhanced when ammonia is replaced with sodium carbonate.

Abstract: An improved process for treating spent alkylation acid to recover a sulfuric acid product suitable for use in wet process phosphoric plants particularly those which recover uranium as a byproduct. The process utilizes heat and agitation to polymerize the liquid, soluble organic impurities normally contained in spent alkylation acid to insoluble, carbonaceous solids. The carbonaceous solids formed are relatively inert in acidic environments, easy to handle and have valuable cation exchange and impurity scavenging properties.

Abstract: A two-stage process for treating acidic gypsum pond water for reuse or for discharge is disclosed. The first stage blends raw acidic pond water with recycled lime-treated slurry from the second stage of the process. The resulting elevation in pH causes CaF.sub.2 and SiO.sub.2 to precipitate and the precipitated material is discarded onto the gypsum storage area. The supernatant water can be used in the wet grinding mill and/or further treated in a second stage with lime to produce treated water which meets government environment standards for discharge. The slurry of calcium phosphate formed in the second (liming) stage is recycled to the first stage.

Abstract: A process for recovering elemental sulfur from volcanic and non-volcanic ores is disclosed. Ore is processed by crushing the ore to a coarse particle size autoclaving to separate the sulfur from the ore, mild grinding to selectively reduce the size of the liberated sulfur particles, flotation and sulfur separation/filtration steps to produce a sulfur of at least 99% purity. The process recovers at least 90% of the elemental sulfur contained in the ore. The particular crushing of the ore and selective grinding techniques for reducing sulfur particles for reducing sulfur particles size are important factors in the efficiency of the process since the grinding techniques inhibit the formation of fine gangue which is difficult to separate from the liberated sulfur.

Abstract: An improved aqueous nitrogen fertilizer has been developed that increases first-year nitrogen uptake efficiency to plants. It is also a nitrogen with features to minimize exposure to nitrogen loss. It is a nitrogen fertilizer consisting of urea, ammonium nitrate, dicyandiamide, ammonium thiosulfate, and a phosphate compound which is preferably an ammonium phosphate compound. This composition can contain a herbicide and/or various micro nutrients. This aqueous fertilizer solution can be applied to a field crop in a single application and is available to the growing plant throughout its growth and maturing cycle. The aqueous fertilizer composition is conveniently prepared by the addition of a slurry containing dicyandiamide, ammonium thiosulfate and the phosphate compound to a urea-ammonium nitrate solution wherein the nitrogen content has been adjusted to account for the nitrogen that will be supplied by the slurry.

Abstract: An improved aqueous nitrogen fertilizer has been developed that increases first-year nitrogen uptake efficiency to plants. It is also a nitrogen fertilizer with features to minimize exposure to nitrogen loss. It is a nitrogen fertilizer consisting of urea, dicyandiamide, ammonium thiosulfate, and optionally a phosphate compound which is preferably an ammonium phosphate compound. This composition can contain a dye and/or various mineral micronutrients. This homogeneous granular fertilizer can be applied to a field crop in a single application and is available to the growing plant throughout its growth and maturing cycle. The homogeneous granular fertilizer composition is conveniently prepared by the addition of a dicyandiamide, and a solution of ammonium thiosulfate to molten urea. A phosphate compound and preferably ammonium polyphosphate, would be added along with these components.

Abstract: A process for the recovery of sulfur from sulfur-bearing ores employing an aqueous leaching solution containing calcium monosulfide, calcium hydrosulfide or mixtures of such calcium sulfide species. The sulfur ore is contacted in an extraction zone with the aqueous leaching solution under conditions to solubilize sulfur from the ore in the form of calcium polysulfide. Preferably, the extraction step is carried out at an elevated temperature. The loaded leaching solution is recovered from the extraction zone and applied to a sulfur-production zone. Here the loaded solution is contacted with hydrogen sulfide under conditions to react the hydrogen sulfide with the calcium polysulfide to produce calcium hydrosulfide and elemental sulfur. The calcium hydrosulfide solution is recycled for use as leaching solution in the sulfur extraction zone.

Abstract: A carbonaceous material, such as coal, is gasified through the catalytic action of an alkali metal salt. The alkali metal is provided as a sulfate which is converted to a sulfide during gasification. In one embodiment, sodium sulfate is converted to sodium sulfide at a temperature effective to form a transitory melt condition at an interface which obtains coal gasification at relatively low temperatures and material residence times for the reaction. An alkaline earth sulfate, such as a gypsum, may be concurrently converted to a sulfide during gasification. The alkali metal sulfide may then be regenerated to a sulfate for process reuse while converting the alkaline earth to a carbonate for environmentally safe disposal with concurrent recovery of valuable sulfur. The evolved carbon gases may be used for fuel, for process feed chemicals, or the like.