A semi-soluble composite granule may include a homogenous powder including a rock phosphate powder making up about 1.0% to about 99% of the homogenous powder and a hydrolyzed humic acid enriched powder making up about 0.05% to about 25% of the homogenous powder; where the homogenous powder is granulated to form a semi-soluble composite granule; and where the composite granule is between about 0.8 mm and about 4.0 mm in diameter.

A method for producing a pedosphere-improving granulate (6) and granulate itself, the method includes a) producing a raw material dispersion including at least one inorganic secondary phosphate (1) and at least one reaction agent (2) in a liquid phase (4), b) separating part of the liquid phase (4) from the raw material dispersion, c) granulating and/or extruding the remaining raw material dispersion with a reduced liquid phase (4), d) either returning the liquid phase (4) separated in process step b) to process step a) in order to produce a raw material dispersion without at least partly separating (5) heavy metals or at least partly separating heavy metals (7) from the liquid phase (4) separated in process step b) and discharging the heavy metals (7) out of the process and subsequently returning the separated heavy metal reduced liquid phase (4) in order to produce a raw material dispersion in a manner analogous to process step a) and/or returning the liquid phase to process step c), and e) repeating process steps a) to d).

A method for producing a pedosphere-improving granulate (6) and granulate itself, the method includes a) producing a raw material dispersion including at least one inorganic secondary phosphate (1) and at least one reaction agent (2) in a liquid phase (4), b) separating part of the liquid phase (4) from the raw material dispersion, c) granulating and/or extruding the remaining raw material dispersion with a reduced liquid phase (4), d) either returning the liquid phase (4) separated in process step b) to process step a) in order to produce a raw material dispersion without at least partly separating (5) heavy metals or at least partly separating heavy metals (7) from the liquid phase (4) separated in process step b) and discharging the heavy metals (7) out of the process and subsequently returning the separated heavy metal reduced liquid phase (4) in order to produce a raw material dispersion in a manner analogous to process step a) and/or returning the liquid phase to process step c), and e) repeating process steps a) to d).

The invention relates to a method for manufacturing an ammonium phosphate fertilizer from a phosphoric acid aqueous solution that has less than 50% P.sub.2O.sub.5 concentration and is obtained by wet phosphate ore treatment, said phosphoric acid containing traces of cadmium, comprising the following steps: (a) neutralizing said phosphoric acid solution (1) with ammonia (3) up to a molar ratio N/P of between 0.1 and 0.8, (b) reacting said partially neutralized solution (4) with a sulfide source (6) so as to form a cadmium sulfide precipitate (9), (c) separating said precipitate (9) so as to obtain a refined ammoniated phosphoric acid solution (10), (d) ammoniating and granulating said refined solution (10) so as to form said fertilizer (12).

The invention relates to a method for manufacturing an ammonium phosphate fertilizer from a phosphoric acid aqueous solution that has less than 50% P.sub.2O.sub.5 concentration and is obtained by wet phosphate ore treatment, said phosphoric acid containing traces of cadmium, comprising the following steps: (a) neutralizing said phosphoric acid solution (1) with ammonia (3) up to a molar ratio N/P of between 0.1 and 0.8, (b) reacting said partially neutralized solution (4) with a sulfide source (6) so as to form a cadmium sulfide precipitate (9), (c) separating said precipitate (9) so as to obtain a refined ammoniated phosphoric acid solution (10), (d) ammoniating and granulating said refined solution (10) so as to form said fertilizer (12).

Fertilizer pellets may be formed by compressing or compacting a primary fertilizer powder mixed with micronized sulphur.

Fertilizer pellets may be formed by compressing or compacting a primary fertilizer powder mixed with micronized sulphur.

The invention relates to the field of slow/controlled release fertilizer, in particular to a urea-formaldehyde-based multi-nutrient slow/controlled release fertilizer and a preparation method thereof. The urea-formaldehyde-based multi-nutrient slow/controlled release fertilizer comprises ammonium polyphosphate, inorganic silica gel and urea-formaldehyde, wherein the phosphorus-oxygen double bond of ammonium polyphosphate can at least form hydrogen bond linkage with a urea-formaldehyde molecule chain, the hydroxyl group of the inorganic silica gel can at least form hydrogen bond linkage with the urea-formaldehyde molecular chain, and ammonium polyphosphate, inorganic silica gel and urea-formaldehyde together form a hydrogen bond associated polymer network structure. The invention can prepare a urea-formaldehyde-based multi-nutrient slow/controlled release fertilizer comprising a strong hydrogen bond network structure by using a conventional aqueous solution polymerization in combination with a normal temperature extrusion granulation process, avoiding the coating process in the latter stage of the preparation of a coated fertilizer, achieving a simple and effective preparation process, and saving a lot of manpower and material resources. The urea-formaldehyde-based multi-nutrient slow/controlled release fertilizer provided by the invention can stably and continuously release nitrogen nutrient throughout the release period, thereby making up for the shortcoming of excessively long nutrient release period of the existing urea-formaldehyde fertilizers.

The invention relates to the field of slow/controlled release fertilizer, in particular to a urea-formaldehyde-based multi-nutrient slow/controlled release fertilizer and a preparation method thereof. The urea-formaldehyde-based multi-nutrient slow/controlled release fertilizer comprises ammonium polyphosphate, inorganic silica gel and urea-formaldehyde, wherein the phosphorus-oxygen double bond of ammonium polyphosphate can at least form hydrogen bond linkage with a urea-formaldehyde molecule chain, the hydroxyl group of the inorganic silica gel can at least form hydrogen bond linkage with the urea-formaldehyde molecular chain, and ammonium polyphosphate, inorganic silica gel and urea-formaldehyde together form a hydrogen bond associated polymer network structure. The invention can prepare a urea-formaldehyde-based multi-nutrient slow/controlled release fertilizer comprising a strong hydrogen bond network structure by using a conventional aqueous solution polymerization in combination with a normal temperature extrusion granulation process, avoiding the coating process in the latter stage of the preparation of a coated fertilizer, achieving a simple and effective preparation process, and saving a lot of manpower and material resources. The urea-formaldehyde-based multi-nutrient slow/controlled release fertilizer provided by the invention can stably and continuously release nitrogen nutrient throughout the release period, thereby making up for the shortcoming of excessively long nutrient release period of the existing urea-formaldehyde fertilizers.

This disclosure relates to water-absorbing and slow/controlled release fertilizer, in particular to a water-absorbing and water-retaining multi-nutrient biodegradable polymeric slow/controlled release fertilizer having a semi-interpenetrating network structure, and preparation methods thereof. The method can comprises the steps of: reacting formaldehyde with urea to obtain a hydroxymethyl urea solution; adding acrylic acid and acrylamide monomers into another reactor, and adding a KOH solution to adjust the neutralization degree of acrylic acid, then adding one of inorganic clay, pretreated crop straw or cellulose, then adding initiator, monopotassium phosphate and the prepared hydroxymethyl urea solution sequentially; allowing to react at temperature after being mixed uniformly to obtain a viscous product; and granulating the viscous product and oven drying the same to obtain the fertilizer. The fertilizer prepared according to the present invention has strong water-absorbing and water-retaining capacity, and an excellent slow release performance for nitrogen, phosphorus and potassium contained as nutrients.