Tennessee Valley Authority

Cecil P Harrison

Cullen G Tittle

J C Mickus

A process for granulating finely divided particulate sulfate or chloride salts of potassium to produce therefrom agricultural products having exceptionally satisfactory physical and chemical properties in regard to bulk blending with other fertilizer blend materials and also in regard to storage and handling properties. The instant methods involve introducing fine-sized, particulate feedstock together with recycle material into a conventional granulator and granulating the solids with use of a water solution comprised of the potassium salt to be granulated and portions of lignosulfonate, which solution has been found to bind the solids material together in a manner and form highly desirable. Drying of the resulting granulation material is required. Nominal grades of the sulfate and chloride granular products are about 47 and 57 percent by weight K.sub.2 O equivalent, respectively.

Granulation of potash materials

The present invention relates to methods and implementation, including apparatus comprising a two-stage, single-unit, and energy-efficient rotary drum-type granulator-dryer device having a granulator section and a separate dryer section in a new and novel combination designed for continuously granulating and/or ammoniating, and subsequently drying, respectively, a variety of materials together with specific processes for effecting such granulating and/or ammoniating, and subsequent drying.

Two-stage, single-unit, and energy-efficient granulator dryer

An improved process for economically and effectively granulating solid, finely-divided, particulate feedstock comprising phosphogypsum, limestone, or mixtures comprising sulfogypsum, natural or mineral gypsum, or mixtures thereof and limestone and having from about 80 to 95 percent by weight of such sulfogypsum/mineral gypsum to effect products which exhibit excellent physical and chemical properties relative to dustiness, storage, handling, and perhaps most importantly, aqueous media-induced rapidity of reversion to a mesh-size distribution of particles substantially similar to the initial size distribution of said feedstock, which improved process involves introducing such relatively finely-divided feedstock, together with material comprising recycle thereof into a suitable agglomeration device, such as a rotary drum, and therein effecting agglomeration/granulation of such feedstock in the presence of aqueous media, the improvement comprising the utilization, in combination with said aqueous media, of relatively small portions of a newly discovered granulation/dispersion aid comprising dilute lignosulfonate solution.

Agglomeration of gypsum, limestone, or gypsum-limestone mix

An improved process for more economically and effectively producing crystalline by-product ammonium sulfate (A/S) by granulating crystalline by-product A/S feedstock and recycle material together with an A/S-sulfuric acid-granulation aid-particle hardener solution and ammonia to bind the crystals together. Underlying the gist of the improvement concept is the identification of a low-cost readily available lignosulfonate by-product of the pulp and paper industry which, when used in predetermined and relatively small proportions, has now been discovered to be very satisfactory as a granulation aid-particle hardener for granulating such by-product ammonium sulfate crystals. Use of lignosulfonate instead of alum, as is currently practiced, reduces the manufacturing cost of granulating by-product ammonium sulfate by about as much as one dollar per short ton of product.

Lignosulfonate as granulation aid-particle hardener

A process for granulating crystalline by-product ammonium sulfate, hereinafter referred to, for the sake of convenience, as A/S, to produce a product having excellent physical and chemical properties as they relate to the storage and handling thereof and also as they relate to the bulk blending of same with other fertilizer blend materials. The method involves introducing the crystalline by-product A/S feedstock, together with recycle material, into a conventional drum ammoniator granulator and granulating the mixture using A/S-sulfuric acid-alum solution and gaseous anhydrous ammonia to bind the crystals together by virtue of the fresh A/S produced and precipitated. Drying in a rotary drum dryer by countercurrent flow of hot gases instead of the more conventional cocurrent gas flow is required.

Granulation of crystalline by-product ammonium sulfate

A process for direct granulation of unpurified urea phosphate from urea and merchant- or filter-grade wet-process phosphoric acid to produce a product with exceptional satisfactory physical and chemical properties for direct application to the soil or for use in production of fluid fertilizers. The process involves the utilization of sweep air in both the reactor and the granulator to remove water from the heat-sensitive urea phosphate mixture to enhance the granulation characteristics of the product. Product drying with applied heat after granulation is essentially eliminated. Moisture content of the urea phosphate is reduced to an acceptable level (about 1.0 percent) in the granulator; however, the granules are somewhat sticky. It has been found, however, that the resulting urea phosphate with about 1.0 percent moisture is less sensitive to heat than high (4 to 6 percent) moisture product. Consequently, heated air (up to about 200.degree. F.) may be applied downstream from the granulator and into the dryer chiefly for control of relative humidity of ambient air introduced therein to less than 40 percent, thereby resulting in still further water removal and curing to effect a very dry and free-flowing product. This alternative is a viable expedient in geographic areas wherein the relative humidity of ambient air is normally in the range of about 50 percent and 80 percent.

Granulation of urea phosphate from urea and merchant-grade phosphoric

A process for granulating crystalline fertilizer borate to produce a product with exceptionally satisfactory physical and chemical properties in regard to bulk blending with other fertilizer blend materials and also in regard to storage and handling properties. The process involves specialized procedures in processing the solid feedstock and granulating the solids with use of a small amount of acid solution. Product drying is not required.

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Florence, AL, United States of America

Cecil P Harrison