MICRONUTRIENT FERTILISER AND METHOD FOR PRODUCING SAME
An improved micronutrient fertiliser comprising leach tailings from a sulphur dioxide leach process for the recovery of manganese or manganese sulphate products and a method for the production of such an improved micronutrient fertiliser, the method comprising the step of blending the leach tailings with a ore or waste containing the appropriate level of sulphide ions that will give the required rate of manganese leaching for the specific soil type.
1 . An improved micronutrient fertiliser comprising leach tailings from a sulphur dioxide leach process for the recovery of manganese or manganese sulphate products and a source of sulphide sulphur, whereby the sulphide sulphur acts to reduce at least a proportion of any manganese present in the +4 valence state.
2 . An improved micronutrient fertiliser according to claim 1 , wherein the source of sulphide sulphur is either or both of a pyritic ore or a waste stream from a sulphide ore flotation circuit.
3 . An improved micronutrient fertiliser according to claim 1 , wherein the amount of sulphide sulphur present is variable dependent upon the level of sulphide ions already present and a desired rate of manganese leaching for a specific fertiliser application.
4 . An improved micronutrient fertiliser according to claim 1 , wherein the improved micronutrient fertiliser further comprises a dispersing agent to maintain undissolved micronutrients in the form of finely divided solids.
5 . An improved micronutrient fertiliser according to claim 1 , wherein the improved micronutrient fertiliser still further comprises a biocide.
6 . An improved micronutrient fertiliser according to claim 1 , wherein the micronutrients present in the leach tailing include any one or more of manganese, iron, calcium, potassium and sulphur.
7 . An improved micronutrient fertiliser according to claim 1 , wherein the original micronutrient content of the leach tailing includes about ≦10% manganese, ≦20% iron, ≦10% calcium and up to about 1% potassium, wt/wt.
8 . An improved micronutrient fertiliser according to claim 1 , wherein the micronutrient content of the fertiliser is about 5-15% manganese, 10-15% iron, 8-12% sulphur and 1% potassium, wt/Wt.
9 . An improved micronutrient fertiliser according to claim 1 , wherein the manganese leach tailing is dehydrated to reduce its water content.
10 . An improved micronutrient fertiliser according to claim 9 , wherein the dehydrated leach tailing has a water content of less than about 10% by weight.
11 . An improved micronutrient fertiliser according to claim 1 , wherein the improved micronutrient fertiliser is provided in the form of an aqueous suspension.
12 . An improved micronutrient fertiliser according to claim 1 , wherein the improved micronutrient fertiliser is provided in granulated form.
13 . A method for the production of an improved micronutrient fertiliser, the method comprising the step of saturating an aqueous phase with both a tailing from a leach process directed to the recovery of manganese or a manganese sulphate product and a source of sulphide sulphur, whereby the sulphide sulphur acts to reduce at least a proportion of any manganese present in the +4 valence state.
14 . A method according to claim 13 , wherein a dispersing agent is added to the aqueous phase to maintain undissolved micronutrients in the form of finely divided solids.
15 . A method according to claim 13 , wherein a biocide is added to the fertiliser.
16 . A method according to claim 13 , wherein the fertiliser is prepared in granulated form.
17 . A method according to claim 16 , wherein the granulation step comprises initial drying of the manganese leach tailings and the source of sulphide sulphur, mixing same with sodium lignosulphate and a surfactant, extrusion and subsequent drying of the resulting granules.
18 . A method according to claim 13 , wherein the micronutrients present in the leach tailing include any one or more of manganese, calcium, potassium, iron and sulphur.
19 . A method according to claim 13 , wherein the original micronutrient content of the leach tailing includes about ≦10% manganese, <20% iron, ≦0% calcium and up to about 1% potassium, wt/wt.
20 . A method according to claim 13 , wherein the micronutrient content of the fertiliser is about 5-15% manganese, 10-15% iron, 8-12% sulphur and 1% potassium, wt wt.
21 . A method according to claim 13 , wherein the blend of the manganese leach tailing and the source of sulphide sulphur is first dehydrated to reduce its water content.
22 . A method according to claim 21 , wherein the dehydrated leach tailing has a water content of less than about 10% by weight.
23 . A method for preparing an improved micronutrient fertiliser in granular form, the method comprising:
a) agitating a blend of spray dried leach tailing having an average particle size of less than 75 micron and a sulphide sulphur source;
b) contacting the agitated feedstock particles with an aqueous granulating agent to agglomerate the leach tailing particles; and
c) recovering a granular leach tailing composition having an average particle size of at least 250 micron.
24 . A method according to claim 13 , wherein the improved micronutrient fertilizer is prepared in the form of a suspension concentrate.
25 . A method according to claim 24 , wherein the method of producing suspended fertiliser is conducted as a batch process.
26 . A method according to claim 24 , wherein the method of producing suspended fertiliser is conducted in batch process comprising the following steps:
a) loading a dehydrated blend of manganese leach tailings and a source of sulphide sulphur to a mill;
b) grinding the dehydrated leach tailings blend;
c) hydrating the ground leach tailings blend with agitation;
d) adding a dispersing agent to the hydrated leach tailing blend; and
e) allowing the hydrated leach tailing blend to settle.
27 - 28 . (canceled)