CN101006190A - Method for nickel and cobalt recovery from laterite ores by reaction with concentrated acid and water leaching - Google Patents

Abstract

A process for leaching laterite ores containing limonite and saprolite in a two stage process. The first stage consisting of mixing and reacting the ore with concentrated mineral acid, and the second stage consisting of preparing a slurry of the acid/ore mixture in water and leaching the mixture to dissolve nickel and cobalt. Iron is efficiently separated from nickel and cobalt in the solid leach residue primarily as an oxide or hydroxide of ferric iron other than jarosite.

Description

By going out the method that from laterite ore, reclaims nickel and cobalt with concentrated acid reaction and water logging

The mutual reference of related application

The application requires to enjoy the right of priority of the U.S. Provisional Patent Application No.60/583243 that submitted on June 28th, 2004, now by reference it is fitted in this specification sheets in disclosed.

Technical field

The present invention relates to the hydrometallurgical process of nickeliferous laterite, carry out the method that acidleach goes out in particular to limonite composition and saprolite composition in same technology to this ore.

Background technology

Laterite is to be formed through original place weathering in geological age by nickeliferous hyper-base (ultramafic) rock that is close to or is in earth surface effect by natural acid precipitation in tropical environment.It comprises multiple clay, oxide compound and silicate minerals, and what have is rich in nickel and/or cobalt, and this makes it be different from another big class nickel minerals---sulphide ores.The latter generally comprises the sulfide mineral of iron, nickel and cobalt, contains copper and small amount of precious metals usually, and relevant with the intrusion of base-ultrabasic magma in the earth's crust.

Efflorescence generally produces bedded deposit, wherein exists completely or sedentary product the most completely near surface, along with degree of depth increase fades to the lighter sedentary product of degree, and terminates as unweathered rock at certain darker degree of depth place at last.Trickle being distributed in the pyrrhosiderite particle in small, broken bits of most of nickel that the height waste mantle contains it usually.Pyrrhosiderite is a kind of oxyhydroxide (oxyhydroxide) of iron, and chemical formula is FeOOH.This layer is commonly referred to limonite, and it generally contains a high proportion of iron.

Cobalt usually with the association of limonite layer, and common more mainly with manganese mineral (oxide compound and the oxyhydroxide that contain Mn (III) and/or Mn (the IV)) association of oxidation, be commonly referred to earthy cobalt or wad.

The lighter contained nickel of layer of weathering generally is contained in the various Magnesium Silicate q-agent mineral more, for example serpentinite.Serpentinite is a kind of silicate minerals of magnesium, has chemical formula 3MgO ^*2SiO ₂ ^*2H ₂O.It is generally acknowledged that nickel has replaced a part of magnesium in the serpentinite.Magnesium also can be replaced by other divalent metals, for example ferrous (Fe ²⁺).Not exclusively have a lot of other in the zone of weathering and contain the silicate minerals of nickel.The height of part weathering contains magnesium ribbon and is commonly referred to saprolite or noumeite.(" noumeite " also is used to describe a kind of magnesium with variable composition-nisiloy hydrochlorate mineral of specific apple green.)

In some mineral deposits, also has the another kind of band that mainly contains the nontronite clay that is in usually between limonite and the saprolite; This nontronite clay is the silicate of magnesium, iron and aluminium, also can be nickeliferous.In the most mineral deposits that are arranged in (at present) torrid zone, the nontronite band is very rare.

It shall yet further be noted that zone of weathering is not uniformly on mineral or chemical constitution, the interface that is parallel between the band on the face of land neither be uniform.But usually there is the quite rapid transformation of and iron level lower---although iron level be variable---ore high relatively to Mg content from the low relatively ore of iron level height and Mg content, this occurs in 1 to 3 meter of vertical range in the laterite mineral deposit.

Only for the purpose of illustration, below provide the typical chemical constitution of limonite and saprolite:

Limonite: 1.0-1.8%Ni, 0.05-0.3%Co, 35-50%Fe, 0.2-3.5%Mg

Saprolite: 1.2-3.5%Ni, 0.02-0.07%Co, 7-20%Fe, 10-20%Mg

In other various mineral, each band also contains aluminium, manganese and the chromium of suitable concentration usually, and other heavy metals of trace, for example copper and zinc.

The where the shoe pinches that nickel is reclaimed from laterite is, can not pass through this metal useful component of the abundant enrichment of physics mode (metal value) usually before carrying out chemical treatment separating nickel useful component, and described physics mode promptly is called the technology of ore dressing.This makes that the processing of laterite is very expensive, is seeking the method that reduces the cost of handling laterite in decades always.

And because different mineral and chemical constitutions in limonite and the saprolite ore deposit, these ores are unsuitable for using same treatment technology to handle usually.

A kind of known acidleach that is used for nickel laterite go out method be called the method that the high pressure acidleach goes out (HPAL) (referring to, the 437-453 page or leaf of " The Winning of Nickel Its Geology; Miningand Extractive Metallurgy " for example, Joseph R.Boldt, Longmans Canada Ltd.1967).This method was used at the Moa of Cuba Bay first in later stage the 1950's, and had set up other factory in the West Australia in the later stage nineties 20th century.

This method is used sulfuric acid---to be generally 250 ℃---at high temperature and is leached under the high pressure; Vapour pressure wherein is about 570psi under 250 ℃.Under this temperature, nickeliferous mineral almost completely dissolve in the ore.Dissolved iron is precipitated as rhombohedral iron ore (Fe rapidly under the high temperature that is adopted ₂O ₃), even this is owing to this compound under this temperature also is difficult to molten in slightly acidic solution.Nickel is stayed in the solution, and ferruginous leaching residue separates from nickeliferous solution by concentrating at a series of washing thickeners (wash thickener)---so-called counter-current decantation washing (CCD) loop---after cooling.Therefore reached the main purpose of extract technology, be about to nickel and separate with iron.

One big shortcoming of HPAL technology is that it needs complicated high temperature and high pressure kettle and relevant equipment, and its I﹠M is all very expensive.In addition, the sulfuric acid of HPAL processes expend is than more by the required sulfuric acid of the non-ferrous metal composition in the stoichiometry dissolving ore, because at high temperature most sulfate ion that is provided by sulfuric acid rests on hydrogen sulfate ion (HSO ₄-) form.In other words, sulfuric acid (H ₂SO ₄) at high temperature only disassociation discharges a proton (H ⁺).Leach liquor cooling and in and the time, hydrogen sulfate ion resolves into sulfate radical (SO ₄ ^2-) and another proton.Therefore a back proton (acid) fully is not used for leaching, and causes excessive must carrying out neutral sulfuric acid, for example uses Wingdale to neutralize.

Another shortcoming of HPAL technology is that it is limited to the raw material that processing is mainly the limonite class, because the existence of saprolite can cause a large amount of and normally uneconomic increase of sulfuric acid consumption, this is owing to the leaching of magnesium in the saprolite is caused.This worsens more owing to bisulfate ion " transformation " problem under the above-mentioned high temperature.

U.S. Patent No. 4,097,575 have described the improvement to HPAL technology, be included in about roasting saprolite ore deposit below 820 ℃ so that ore and vitriolic reactive behavior are stronger, use in the calcining of stoving oven then and excessive acid in the discharge of autoclave, the pressurization that limonite takes place in described autoclave is leached.The nickel that contains in the saprolite ore deposit in this N-process dissolves in a large number.It is said that the advantage of this technology is that it utilizes the sulfuric acid that adds better in limonite pressurization leaching process, reduce the Wingdale that is used for handle high voltages still discharge liquid or the consumption of other expensive neutralization reagents, and obtained ability that the limonite composition in the typical nickel laterite body and saprolite composition are handled.The shortcoming of this technology is that it still needs to use expensive autoclave to be used for the leaching of limonite, and need carry out calcination process to the saprolite ore deposit, and this processing all is very expensive on fund input and running cost.

U.S. Patent No. 6,379,636 B2 have described U.S. Patent No. 4,097, the further improvement of the technology of describing in 575, wherein removed saprolite calcination steps and saprolite that will " nature " state be used for autoclave discharge solution in excessive acid.In addition, can add more acid in relief liquor can the leaching amount with what increase saprolite.But this technology still needs to use expensive autoclave.

Also put down in writing some and only used the technology that acidleach goes out under the normal atmosphere, they have eliminated the shortcoming that above-mentioned pressurization is leached.U.S. Patent No. 3,793,432 have described and a kind of laterite ore have been carried out the technology that normal atmosphere leaches, and wherein make ore and sulfuric acid at boiling point or be lower than under the boiling point and react, and by adding the iron precipitation agent, for example ammonium, sodium, potassium or lithium ion make dissolved iron precipitation.Although clearly do not propose, all examples of quoting in the specification sheets have all used the limonite sample, and this can be proved by the high Fe content and the low Mg content of raw ore.Though this technology has overcome the shortcoming that pressurization is leached, it has other shortcoming.At first iron is with jarosite compounds form precipitation, and this is the compound of a kind of thermodynamic instability of iron, can decompose along with the time to discharge sulfuric acid, therefore causes environmental problem.(although jarosite is not clearly proposed, and clearly can be settled out jarosite under the listed condition in example to those skilled in the art).Per three moles iron correspondences contain two molar sulphur acid groups in the jarosite, and therefore this compound means for providing necessary sulfate ion to need quite excessive sulfuric acid consumption.

The second, the extraction yield of nickel from ore is obviously lower.Although extraction yield does not clearly provide, must be according to the content of nickel in the residue and residue weight greater than the fact of raw ore weight---this be since the iron percentage composition in the jarosite than low in the raw ore and almost all iron all be retained in the residue, the extraction yield of nickel is usually in the scope of 60-65%.The 3rd, need very long extraction time, magnitude is 4-5 days.The 4th, need to add more expensive relatively iron precipitation agent for example salt of wormwood, yellow soda ash etc.

U.S. Patent No. 6,261,527 B1 and 6,680,035 B2 has described another kind of normal atmosphere extract technology, wherein at first uses the vitriol oil that limonite ore is carried out " fully " and leaches, and this is dissolved out from pyrrhosiderite to be about to nickel and iron-based, leach in the slurry at the limonite that obtains then the saprolite ore deposit is leached, by adding the precipitation as jarosite agent iron is precipitated out with the form of jarosite simultaneously.This technology has the shortcoming that produces jarosite equally, need dig up mine respectively and prepares the limonite of ore and saprolite composition, and only limit the use of in the scope of very narrow saprolite to the ratio of limonite.The shortcoming in back is because the amount that effectively can the leaching amount depends on the iron in the limonite infusion solution of saprolite.

WO 03/093517 A1 has described a kind of improvement to this technology, forms for example adding of sodium, potassium or ammonium of ion of jarosite comprising cancellation, and iron is precipitated out with the compound form beyond the jarosite, for example pyrrhosiderite.This technology has overcome the shortcoming of jarosite, but sulfuric acid consumption is 0.59 to 0.87 ton of sulfuric acid/ton ore in the example of being quoted, and has nine to surpass 0.72 ton of sulfuric acid/ton ore in 11 examples being quoted.

U.S. Patent No. 6,261,527 B1 and 6,680,035 B2 and the described technology of WO 03/093517 A1 based on pyrrhosiderite than the common saprolite mineral more difficult fact that is gone out by acidleach of serpentinite for example.This confirms by other investigators (referring to, John H.Canterford for example, " Leaching of Some Australian Nickeliferous Laterites withSulfuric Acid at Atmospheric Pressure; " Proc.Australasian Inst.Min.Metall., 265 (1978), 19-26; N.M.Rice and L.W.Strong, " TheLeaching of Lateritic Nickel Ores in Hydrochloric Acid, " CanadianMetallurgical Quarterly, 13 (3) (1974), 485-493; And Fig. 5 of United States Patent (USP) 5,571,308).Therefore, have only saprolite to effectively utilize, the precipitation of iron takes place in described subordinate phase simultaneously in the subordinate phase that leaches.This is because the acidity of solution must be relatively low so that jarosite can precipitate, even lower so that pyrrhosiderite or ferric other hydrolysate can precipitate.Pyrrhosiderite contained in the limonite leaches very slow under such condition.Therefore use higher relatively acid concentration that limonite (being mainly pyrrhosiderite) is leached and iron and nickel are all brought in the solution in the fs.

U.S. Patent No. 3,244,513 have described a kind of method, the laterite that wherein is mainly limonite class (being defined as＞25% iron) mixes with the vitriol oil in the presence of limited amount water, then with mixture at about 500 to 725 ℃ roasting temperature, so that the useful component of nickel, cobalt, magnesium and manganese has precedence over iron generation sulphating.Water logging afterwards goes out to obtain nickel and the high extraction of cobalt and the low extraction yield of iron in the solution.The advantage of this method is that it does not need to use expensive autoclave to leach.Topmost shortcoming is that it need carry out expensive calcination steps.

U.S. Patent No. 4,125,588 have described and U.S. Patent No. 3, similar method described in 244,513 is except having following difference: omitted calcination steps, and carefully control mixing of ore and the vitriol oil, in described mixing, at first do not having under the condition of the water that obviously exists ore to be mixed with the vitriol oil, and then the water of adding manipulated variable adds entry at last more in addition mixture is leached with the sulfation of initiation ore.The advantage of this method is that it has cancelled U.S. Patent No. 3,244,513 required calcination stepses.But this method also has very big shortcoming.

One of shortcoming is that the moisture that employed ore contains should not be higher than 1%, this means that in most of the cases ore must be through super-dry, and this is because the original place water capacity of laterite is generally 20% or more.Second shortcoming shown in whole examples of quoting in this patent, the selective dissolution (＞90% iron extraction yield) that this method does not provide nickel to be better than iron.Nickel in the solution separated with iron cause the loss of other nickel usually.

In addition, this method only is applicable to the ore that contains " a large amount of magnesium oxide and silicon-dioxide ", i.e. saprolitic ores or noumeite stone.Though the accurate composition of citation ore in whole examples not can find out obviously that from the data that provide magnesium that ore contains is 3 to 4 times of iron, has clearly illustrated and has not considered limonite ore (iron/magnesium weight ratio is about 10 to 90).And acid consumption is very high in the method, is about 0.9 to 1.1 ton of sulfuric acid/ton ore.

U.S. Patent No. 3,093,559 have described the method that the denseer relatively sulfuric acid (about 25 to 50% sulfuric acid) of another kind of use is handled laterite.In the method, add the acid of capacity so that comprise great majority or whole metal useful component sulfation of iron.Make iron be converted into rhombohedral iron ore by infusion solution being evaporated to the dry doubling salt that roasting obtained under 975 to 1050  then, thereby iron is separated with nickel.Leaching again to calcining afterwards makes nickel enter solution, and iron is stayed in the residue.As above-mentioned various technologies, need carry out the high-temperature roasting step and be a remarkable shortcoming in the technology.

U.S. Patent No. 2,899,300 have described a kind of method, wherein use the vitriol oil that the laterite of humidity is handled, then between 100 ℃ to 150 ℃, under the preferred 125 ℃ temperature that the mixture baking is dry, and then carry out water logging and go out with the metal useful component in the dissolving ore.Baking procedure is a significant defective, because it needs a large amount of heat energy with contained water in evaporation ore/acid mixture.And as described in the example that provides in the specification sheets, the dissolution rate of nickel is relatively low and dissolution rate iron is higher relatively, be respectively～77% and 53%.It is said can be by adding in addition sulfuric acid and carry out the secondary sulfation and water logging goes out step in the residue of fs, thereby the nickel extraction yield is improved, but this separation that can increase the complicacy of technology and can not improve iron/nickel in this technology.

U.S. Patent No. RE37,251 have described a kind of technology, its by use contain bisulfate ion and sulfate ion and halide-ions for example the acidic solution of chlorion and oxygen to the leaching of pressurizeing of the non-cuprous ore that comprises nickel laterite and enriched material.According to specification sheets, required temperature and pressure is respectively 225 ℃ and 450psig O ₂Consider that the vapour pressure under 225 ℃ is approximately 370psi, total pressure should be in the scope of 820psig.The condition that these conditions and high pressure acidleach go out is closely similar, therefore as mentioned above, needs to use expensive autoclave system.

The objective of the invention is to eliminate or reduce the shortcoming of these already known processes.Further purpose provides a kind of mixture to limonite ore and saprolitic ores and carries out the method that acidleach goes out, the mixture of described limonite ore and saprolitic ores does not carry out any follow-up ore kind to be separated and obtains by general laterite ore body being carried out whole mining, present method is carried out under normal atmosphere or lower pressure, can obtain the high extraction of nickel and cobalt and the final extraction yield of low-down iron.

Summary of the invention

The invention provides a kind of method that from limonite ore and saprolitic ores, nickel and cobalt is fully leached, described limonite ore and saprolitic ores can obtain by general nickel laterite bed being carried out integral body mining, present method is divided into two stages, fs comprises gives birth to reaction with ore and dense mineral acid hybrid concurrency, subordinate phase comprise preparation acid/ore mix in water slurry and mixture leached with dissolving nickel and cobalt.Iron enters solid mainly as ferric oxide compound beyond the jarosite or oxyhydroxide and leaches residue, separates effectively with nickel and cobalt.

Present method can also be included in water logging and blended ore and acid be carried out slaking before going out, ore mix with acid and react before at first with its fragmentation.Preferred independent broken saprolite, and then mix with limonite.More preferably earlier acid is mixed with limonite, and then add saprolite.

Water logging goes out and can advantageously carry out under the temperature that suitably improves.Leach for normal atmosphere, preferably in 95-105 ℃ temperature range, carry out.Perhaps, can be by in autoclave, leaching faster being up to leach under about 150 ℃ temperature obtaining.Corresponding pressure is to be up in the pressure range of 70psia, approximates the saturated vapor pressure under this extraction temperature greatly.

Used acid is preferably selected from sulfuric acid, hydrochloric acid or nitric acid, more preferably sulfuric acid.Also can use the mixture of above-mentioned acid.

Advantageously, water logging go out can add in the process reductive agent for example sulfurous gas, hydrogen sulfide, soluble hydrosulphite and sulfite compound or soluble ferrous compound to strengthen the dissolving of cobalt.

The generation that method of the present invention has been avoided using expensive autoclave and reduced jarosite compounds.In some embodiments, also exempted limonite class ore and sapropel great soil group ore is exploited respectively and necessity of handling respectively, also made it possible to handle the ore of large-scale saprolite the limonite ratio.

Find that also the present invention can obtain at least about 80% nickel extraction yield and nearly 95% or higher cobalt extraction yield, have simultaneously to be lower than about 15% iron extraction yield.

Description of drawings

Fig. 1 is for having shown the schema of a kind of embodiment of the inventive method in simplified form.

Fig. 2 has shown another embodiment of the inventive method, wherein a part is leached the residue recycling as the sedimentary crystal seed of iron.

Fig. 3 has shown the third embodiment of the inventive method, wherein at first whole required acid is mixed with limonite ore, and then saprolitic ores is mixed with the limonite/acid mixture of acquisition.

Fig. 4 has shown the 4th kind of embodiment of the inventive method, wherein at first whole required acid is mixed with limonite ore, saprolitic ores and water with fragmentation adds in the limonite/acid mixture that obtains then, and mixture grinding carrying out the again normal atmosphere with gained leaches afterwards.

Embodiment

The invention provides a kind of improved method and be used for extracting nickel and cobalt, most of iron contained in the ore is got rid of at solid leached in the residue simultaneously from nickeliferous laterite.Present method does not need to carry out in advance separating of limonite ore and saprolitic ores, and can handle the mixture of two types of ores.But be convenient to exploit respectively under the situation of limonite ore and saprolitic ores, can obtaining the high extraction of nickel by at first directly making the acid and the method for limonite ore reaction and then adding saprolitic ores.

Referring to Fig. 1, at first will be crushed to about 5mm to 10mm upper limit size by the laterite raw ore that the mixture of limonite and saprolite is formed.Ore with fragmentation for example mixes in the mixer-mill in suitable device with dense mineral acid then, and described mineral acid is selected from the mixture of sulfuric acid, hydrochloric acid and nitric acid or above-mentioned acid.Ore generally contains a large amount of free water contents under the raw ore state, needn't carry out drying to ore before adding concentrated acid.

The add-on of acid was at least in the follow-up leaching stage dissolves the required amount of soluble non-ferrous metal (not comprising iron) in the ore by stoichiometry, and described non-ferrous metal is most of nickel, cobalt, magnesium, aluminium, copper, zinc and the sub-fraction chromium in the ore.Add a small amount of excessive acid providing certain free acidity, thereby leach a spot of iron, and guarantee the maximum extracted rate of nickel and cobalt in the follow-up leaching stage.The add-on of restriction acid is to guarantee to extract the final extraction yield minimum of iron from ore pulp.In some cases, some magnesium and aluminium may be insoluble, this situation need be taken into account to determine definite sour add-on.

The add-on of water is reduced to and can makes the degree that reaches maximum concentration with the acid of mineral reaction in the acid mixing process.Have only ore/acid mixture firmly just to be necessary to add entry to can not mix fully or be difficult for processing the time.In the ore of humidity, add concentrated acid and cause producing a large amount of heat, make the temperature of mixture be increased to the boiling point of---even being higher than---water and cause a large amount of evaporations of water.If desired, can add entry in addition in mixing process makes it reach pasty state fluidic degree with the denseness of controlling acid/ore mix.If do not add entry,, also may form drying, pulverous reaction product according to the water capacity and the net calorific power of ore.(may form the intermediateness of pasty state fluid and dry powdered material, promptly hard caramels shape mixture, this mixture may more be difficult to handle).

In theory, both can to have had pasty state fluidic denseness also can be dry powdered denseness so that it is easy to handle to mixture.Acid/the ore mix of gained---perhaps " pug "---can at room temperature be carried out " slaking ", and the curing time should be enough to make the mineralogical composition in mineral acid and the ore almost completely to be reacted.Described slaking can be by leaving pug on the ready no infiltrative pad and pug being left standstill several days on pad, then with salvage material and be used for next step and handle and finish.

For ease of depositing and reclaim, may be before depositing by material is for example extruded or granulation to form the discontinuous pug of aliquot.But find to use the minimum curing time or the curing time of nothing may obtain satisfied result.In this case, acid/ore mix directly can be mixed with water.If ground ore before adding acid, then after unnecessary the grinding.The water logging of the slaking of longer time after may making it go out step obtain slightly high any the nickel extraction yield and lower iron extraction yield.

After the slaking, pug is ground to the granular size that is enough in steel basin, leach.Easily, the required water that leaches slurry that is used to form can be added before grinding, so that grinding steps carries out under moisture state.Pug grinds the granular size that is reached should be enough to make that most of particle becomes the suspended solids that leaves the bottom surface under the condition that does not need too much agitation energy input in slurry.Need make slurry dense as far as possible thick under the situation that guarantees good mixing in leaching process, thereby make required least amount of water also generate the leaching mother liquor of the denseest nickeliferous and cobalt.

With leaching slurry heating on demand in the batch leaching reactor of gained, perhaps, the heating on demand in a series of leaching reactors if process is carried out continuously.The temperature that leaches slurry preferably is controlled at the normal boiling point of leach liquor or near this boiling point, is generally 95 to 100 ℃.Can use live steam to inject or other method increase heat energy for reaching this purpose.The required heat of a part is provided by the heat of the solution that contains excessive acid and metal-salt that forms in the sour mixing step.In addition, thereby can be in the pug forming process pug reactor be lowered the temperature water preheat by the water that need use when leaching, perhaps steam by producing in the recovered acid ore reaction process, thus reclaim another part heat.

Can make and leach mixture and react most nickel in ore and cobalt dissolving and most iron and enter solid and leach in the residue.The magnitude of the hold-time of agitation leach is 12 to 48 hours.Generally in about 15 hours or less time, can obtain satisfied result.In some cases, the reductive agent that may need to add manipulated variable in leaching slurry is to strengthen in the ore leaching with the symbiotic cobalt of manganese mineral (for example asbolane) of oxidation.For example, can controlledly add sulfurous gas to improve cobalt (with the leaching of manganese), this is conspicuous for those skilled in the art.Can also use other trivalent and tetravalence Mn oxide can be reduced to the reductive agent of divalent state.

The temperature that can be above the boiling point by use is to accelerate leaching process significantly.For example be heated to about 150 ℃, extraction time can be reduced to about 1 hour by in autoclave, leaching slurry.It may be useful further improving temperature, leaches relevant complicacy but an object of the present invention is to eliminate with high pressure.Should point out to leach down required pressure of slurry that pugs the add water 70psia (vapour pressures under 150 ℃) that only has an appointment at 150 ℃.Under this pressure, can use conventional impeller pump with mashing pump to autoclave, and depressurizing system can be very simple one valve or throttle gate (choke).Be applicable to that the autoclave equipment of the present invention autoclave required with carry out the high pressure leaching under temperature about 250 ℃ and the pressure about 450-500psia differs widely, this is conspicuous for those skilled in the art.

The temperature that use is above the boiling point also can obtain higher nickel/iron ratio in solution, this downstream processing for infusion solution is useful.This is owing to nearly all iron must be removed from solution before the recovery of carrying out nickel and cobalt as a rule.Usually, by in leaching slurry, adding alkali, lime carbonate for example, and be settled out hydrous iron oxide (iron oxyhydroxide) compound and remove iron residual in the solution.Part nickel can cause the loss of this precious metals (pay metal) with the iron co-precipitation, and neutralizing agent also means running cost extra in the technology in addition.Using another advantage of comparatively high temps is that the solid/liquid separation performance that finally leaches slurry is improved, because can obtain higher settling velocity under higher extraction temperature.

In some cases, it may be favourable using normal atmosphere leaching and follow-up middle pressure to leach successively.Can most convenient ground add and be used to leach the manganese mineral of oxidation and contained cobalt and the sulfurous gas of nickel useful component or other reductive agent in the normal atmosphere leaching stage.Can also use follow-up pressurization to leach the advantage of pointing out in step realization the preceding paragraph.

The present invention can obtain at least 80%, can be up to nickel extraction yield and the corresponding iron extraction yield that is low to moderate 5-10% of 90-95%.In addition, leach in the residue and generally contain the sulphur that is no more than about 1-2%, illustrate that iron cpd master in the residue is if it were not for the jarosite class.

When sulfuric acid is used as leaching agent, this extract technology of the present invention and prior art be U.S. Patent No. 3 for example, 244,513 difference is, prior art is mixed the whole ferric sulfate that use calcination steps to form so that acid is mixed in the back in acid and is converted into ferric oxide.In this conversion process, discharge sulphur trioxide (SO ₃) gas, sulfur trioxide gas and non-ferrous metal oxide compound be NiO and the non-iron sulfate of MgO reaction formation for example.Therefore the preferential sulfation of non-ferrous metal in the method for prior art.

But, find surprisingly now, costly and need a large amount of expensive fuel energy reaching for example 500-700 ℃ calcination steps of required maturing temperature, thus the leaching mother liquor of be not selectively sulfatedly to go out the back and obtain to contain most solvable non-ferrous metal ore/acid mixture being carried out water logging for what reach non-ferrous metal---especially nickel and cobalt---and relative less iron is necessary.Required just goes out to provide in the process time enough and temperature to realize required reaction in water logging.Therefore cancel calcination steps and embody a big advantage with respect to prior art.

After water logging goes out, carry out solid/liquid separation by filtering or concentrating to leaching slurry, to obtain to contain the leaching mother liquor of most of nickel contained in the ore and cobalt and the solid residue that contains most of iron contained in the ore.Advantageously, concentrate under the situation of washing current and leaching slurry adverse current in a series of thickeners, wash out with most of metal useful component that will carry from leach residue, this method is called counter-current decantation washing (CCD).The metal useful component mainly converges in the thickener overflow (overflow) of first thickener, obtains leaching mother liquor.

Leach mother liquor and then carry out the recovery of nickel and cobalt by method known to those skilled in the art, the for example solvent extraction of described method, ion-exchange, use vulcanizing agent for example hydrogen sulfide carry out sulfide precipitation, or for example use that magnesium oxide carries out precipitation of hydroxide as precipitation agent.

Can also not carry out solid/liquid separation earlier and use the resin-in-pulp exchange process that nickel and cobalt are reclaimed from leach slurry.In this technology, in leaching slurry, directly add the ion exchange resin of extraction nickel and possible cobalt.After extracting end, make resin and the leaching pulp separation of having removed nickel by screening.Clean resin with after removing solid, can use fresh acid solution that nickel is eluted from resin.

In the process that reclaims nickel and cobalt by one of aforesaid method or before this, can use alkali, for example in lime carbonate, magnesium oxide, the yellow soda ash etc. and infusion solution, the free acidity that left behind from leach step to neutralize also precipitates a spot of ferric iron, aluminium and chromium, and the co-precipitation of nickel and cobalt is minimized.This process can be finished by single or multiple steps, a plurality of step midfeather solid/liquid separation.

In one embodiment of the invention, can before will leaching residue and infusion solution separates, carry out the first step neutralization.Then can with the leaching that merges and in and residue by filtration or concentratedly from part neutral infusion solution, separate, as mentioned above.According to the selected method that from leach mother liquor, reclaims nickel and cobalt, may also need the neutralization of second step.After the second step neutralization, can by filter or concentrate will obtain in residue with neutralize after infusion solution separate.Preferably be back to the first step neutralization with residue in second step, with nickel and the cobalt that dissolves any co-precipitation again.

Finding surprisingly needn't be in order to divide other different processing to limonite in the laterite and saprolite and the two to be separated in leaching process.And as long as reach the minimum ratio of a certain at least saprolite/limonite, this technology is not limited to any specific saprolite/limonite ratio.Can add the amount of the acid of ore at the ratio range adjustment of saprolite/limonite according to the content of non-ferrous metal in saprolite/limonite ore mixture.

Also finding surprisingly needn't be as the same iron precipitation agent that adds in leaching slurry in the U.S. Patent No. 3,793,432.For example sodium, potassium and ammonium ion are disadvantageous to add the iron precipitation agent, because impelling, these ions generate ferruginous jarosite compounds, jarosite compounds is a thermodynamic instability, can discharge sulfuric acid slow the decomposition along with the time, thereby cause leaching the dissolving again of metallic impurity in the residue and may cause environmental pollution.In addition, need extra sulfuric acid to form the required sulfate ion of jarosite in the leaching process to satisfy.

In the method for the invention, when for example sulfuric acid added in the ore, other non-ferrous metal were not had selectively sulfation in nickel, cobalt and iron and the ore in acid/ore mixing step, promptly are converted into vitriol.Vitriol is easy to dissolve in water in follow-up leaching step.But because the quantity not sufficient of the initial acid that adds is converted into vitriol so that comprise all metals of iron, the therefore initial nickel and the extraction of cobalt are incomplete.Therefore, a considerable amount of iron enter solution with nickel, cobalt, magnesium, aluminium, chromium, copper and zinc.But by the leaching process that continues after the initial vitriol dissolving step, iron level reduces in the solution, and further extracts nickel and cobalt from solid phase.Definite iron leaches and the redeposition reaction still is unknown, but the sulphur content in the final residue is very low, usually less than 2%, illustrates that the formation of jarosite does not reach significant degree.

Of the present invention a kind of preferred embodiment in, the initial stage that goes out step in water logging adds ferruginous " crystal seed " material in leaching slurry, purpose be accelerate dissolution iron precipitation and quicken from solid phase, to extract remaining nickel and cobalt.The surface of seed particles is the hydrolysis and the precipitation of iron the form of ironic hydroxide, pyrrhosiderite or red iron-stone---for example with---provides the low-activation energy site.Seed crystal material preferably contains the part of the final leaching residue of sedimentary iron cpd itself.Fig. 2 has shown a kind of method of using crystal seed circulation implementing process.

In another embodiment of the invention, at first the part of the limonite in the ore to be mixed with concentrated acid, the amount of acid is calculated according to method as hereinbefore, then the saprolite in the ore is partly added in limonite/acid mixture.Saprolitic ores can be added in limonite/acid mixture with the saprolite of fragmentation or the saprolite form of grinding.For the previous case, earlier ore/acid mixture is ground before going out carrying out water logging, can under the situation that does not add water, grind.Advantageously, can in ore/acid mixture, add entry and carry out wet lapping before going out carrying out the normal atmosphere water logging.For latter event, can under drying conditions, saprolitic ores be ground and then add in acid/limonite mixture, perhaps in wet lapping and the form adding limonite/acid mixture with slurry or filter cake with water.As previously mentioned water logging being carried out in the blended ore of gained and acid then goes out.Present method is most possibly with the pyrrhosiderite composition sulfation in the laterite.Fig. 3 has shown the schema that carries out this embodiment of the present invention.

Following embodiment has illustrated method of the present invention.The ore that uses among these embodiment is from laterite mineral deposit, Central America.Limonite and saprolite composition in the used ore of embodiment 1-3 have the composition that provides in the table 1.Saprolitic ores is being used for being crushed to pact-6.4mm before the test.

Table 1

	％Ni	％Fe	％Mg	% moisture
					Limonite ore	1.41	47.7	0.67	34.5
Saprolitic ores	3.17	8.7	17.8	21.3

Embodiment 1

Will about 1kg saprolitic ores wet lapping in ball mill to about 100% by 100 mesh sieves.Is 41% grinding saprolite with the slurries filtration after grinding to make water capacity.The grinding saprolite of 425.2g humidity mixed with the limonite ore of 381.7g humidity to make 500g have limonite/saprolite of 1: 1 than the leaching raw material of (with drying solid).

Ore mix is put into 4.5 liters of tenuicollis bottles.Bottle is gone up to roll under about speed of 47 to 48rpm with the angle of horizontal direction slight inclination at bottle rolling equipment (bottlerolling device).With about 30 minutes the sulfuric acid of 312.5g 96% is added in the ore mix in the bottle.After all acid adds, ore was mixed about 30 minutes with acid.Mix ore and acid formation semi-fluid material when finishing, temperature is elevated between about 70 to 100 ℃.

Bottle is taken off from rolling equipment, make about 72 hours of the acid and the mixture slaking at room temperature of ore.In the material of slaking, add 622mL water then, stir the mixture until the leaching slurry that forms homogeneous.To leach slurry and transfer in 2 liters of round shape reactors that a mechanical stirrer, 4 plastic dam (baffle) and the lid that closely cooperates are housed, the described lid that closely cooperates is equipped with the water condenser that opens wide to atmosphere.Use external electric mantle that reactor is heated.

To leach slurry and be heated to about 96-99 ℃ and remained on this temperature following 48 hours, simultaneously vigorous stirring.Leach after 5 hours, in reactor, add 129g levigated technical grade rhombohedral iron ore as iron sedimentary " crystal seed ".Regularly gather the leach liquor sample to carry out chemical analysis.When leaching process finished in 48 hours, with whole slurries filtrations.In fresh water, filter cake carried out twice again pulp to wash out the metal useful component that carries.Then filtration cakes torrefaction is weighed.Analyze the washing water of drying solid, filtrate and merging respectively.

This test-results is provided by following table 2 and 3.

Table 2

Time (h)	[Ni]g/L	[Fe]g/L	[Mg]g/L	[H 2SO 4]g/L
1	8.8	70	27	＜0.5
					2	8.0	49	27	＜0.5
5	9.5	24	35	＜0.5
					24	8.7	14	35	8
32	8.3	12	32	9
					48	8.8	10	28	16

Table 3

	Ni (% or g/L)	Fe (% or g/L)	Mg (% or g/L)	S(％)
Final solution	9.3	12.8	39	--
					Final residue	0.34	42.9	0.52	0.98
The extraction yield of calculating *	85.2	11.7	94.9	--

^*Based on Ni, the Fe of weight, volume and the analytical results of final residue and final solution and the extraction yield of Mg

The result shows and obtained higher nickel extraction yield, simultaneously to the extraction of iron in ore seldom.In addition, the sulphur content in the residue is quite low, and the Fe/S ratio was near 44: 1.Containedly in the sulfuric acid be lower than 5% sulfate radical and enter in the residue.If iron whole in the ore all form jarosite, the Fe/S ratio in the final residue should be near 4.3.In addition, the X-ray diffraction analysis of residue has been illustrated that the rhombohedral iron ore, pyrrhosiderite and the spinel that have only occurred in the initial ore are mutually.

The dynamics data explanation need be slightly more than 24-32 hour leaching to reach concentration of iron final in the solution.Can by use alkali for example Wingdale neutralize residual iron removed from solution, and do not produce the remarkable loss that nickel enters solid phase.

Embodiment 2

381.7g limonite ore sample is mixed in 2 glass beakers of the peaceful end with the saprolitic ores and the 95g water of 317.7g fragmentation.Adding entry is in order to simulate the expectation water capacity of raw ore ore, to will be appreciated that sample is slightly more dried than its in-situ state.With the sulfuric acid that adds 312.5g96% in the about 30 minutes clockwise beakers.Use agitator under the rotating speed of 60rpm, acid to be mixed with ore.The add-on of acid is enough to make that acid is about 600kg H to the ratio of ore ₂SO ₄/ ton ore (in dry product).

The semi-fluid material that ore and acid are formed is poured onto in the tray with slaking at room temperature about 72 hours.A part of mixture is not recovered in this process, in weight recovery, estimates that about 13% mixture is not recovered.

Behind the maturing process, the acid/ore mix of significantly hardening is broken into piece and transfers in the small-sized shredder.In shredder, add 300g water, use about 1 hour of stone medium milling mixture the largest particle size is reduced to about 100 orders.Adding entry in shredder in addition leaches in the reactor slurry is flushed to 2 liters.Prepare 1 in this way, 858g leaches slurry.Reactor is heated to 95 to 105 ℃, stirs simultaneously, and continue to carry out 44 hours leaching.Leach after 5 hours, in reactor, add 129g levigated technical grade rhombohedral iron ore as iron sedimentary " crystal seed ".Regularly gather the leach liquor sample carrying out chemical analysis, when leaching process finished in 48 hours, with whole slurries filtrations.In fresh water, filter cake carried out twice again pulp to wash out the metal useful component that carries.Then filtration cakes torrefaction is weighed.Analyze the washing water of drying solid, filtrate and merging respectively.

This test-results is provided by following table 4 and 5.

Table 4

Time (h)	[Ni]g/L	[Fe]g/L	[H 2SO 4]g/L
1	4.6	25.6	＜0.5
				2	5.36	29.7	＜0.5
5	6.15	15.5	5
				24	4.73	4.74	12
44	5.49	7.55	16

Table 5

	Ni (% or g/L)	Fe (% or g/L)	Mg (% or g/L)	S(％)
Final molten	5.51	8.7	22.0	--
					Final residue	0.41	42.8	0.47	0.83
The extraction yield of calculating *	81.1	11.3	94.7	--

^*Based on Ni, the Fe of weight, volume and the analytical results of final residue and final solution and the extraction yield of Mg

This test simulation of the present invention one preferred embodiment, wherein saprolitic ores mix with limonite ore and add acid before do not grind.Replace after slaking acid/ore mix is ground.

The result of this test is similar to the result of embodiment 1, but the nickel extraction yield is lower slightly.

Embodiment 3

The mode that this test is carried out is similar to embodiment 2, has following difference simultaneously.In the acid mixing process and in the leaching process afterwards, the consumption of saprolitic ores, water, acid and the rhombohedral iron ore crystal seed of limonite ore, fragmentation is respectively 336.9g, 280.3g, 84g, 275.8g and 113g.Identical among the ratio of ore, water and acid and the embodiment 2.

Ore with after acid mixes, is transferred on the tray also slaking only 1 hour with mixture, transfer to then in the shredder, carry out water logging afterwards and go out to carry out wet lapping.After 1 hour the slaking, mixture still also can be dumped in the shredder for fluid.Prepared 1,776g leaches slurry and uses with embodiment 2 duplicate methods and leach.The rate of recovery of acid/ore mix is near 96%.

This test-results is provided by following table 6 and 7.

Table 6

Time (h)	[Ni]g/L	[Fe]g/L	[H 2SO 4]g/L
1	5.53	22.7	＜0.5
				2	6.37	24.2	＜0.5
5	7.59	16.7	4
				24	7.4	9.14	13
44	7.12	10.8	16

Table 7

	Ni (% or g/L)	Fe (% or g/L)	Mg (% or g/L)	S(％)
Final solution	6.97	10.2	34.0	--
					Final residue	0.37	43.0	0.45	0.81
The extraction yield of calculating *	84.2	10.8	95.2	--

^*Based on Ni, the Fe of weight, volume and the analytical results of final residue and final solution and the extraction yield of Mg

Embodiment before the result of this test is similar to has proved and needn't carry out long slaking to ore/acid mixture before leaching.

Embodiment 4

The ore that uses in this test has the composition that provides in the table 8.

Table 8

	％Ni	％Co	％Fe	％Mg	％Si	% moisture
							Limonite ore	1.31	0.2	47.2	0.63	2.67	41.9
Saprolitic ores	3.13	0.01	6.0	20.0	18.8	14.4

409.6g (in wet product) limonite ore is put into the porcelain ball mill that 0.6-1.9cm porcelain ball is housed.Before adding ore, shredder and grinding medium are preheating to about 100 ℃.This is the heat condition when carrying out continuously for simulation process.Shredder is equipped with center foraminous plastic cover, can add sulfuric acid by described hole.Use the roller press grindstone among the embodiment 1.Sulfuric acid with adding 338.5g 96% in the about 1.5 minutes clockwise shredders makes limonite ore and acid-respons 15 minutes.In reaction process, use the temperature in the hand-held laser temperature meter monitoring shredder.The temperature that records changes between 97 to 121 ℃, adds in acid to record top temperature in about 1 minute after finishing.When reaction is finished, shredder is taken off from roller press, take lid, adding broken saprolitic ores of 306.1g (in wet product) and the Mg of 510g 30g/L in limonite/acid mixture (is MgSO ₄) aqueous solution.Use MgSO ₄Solution is to reclaim the effect of the remaining lean solution in back as reuse (make-up) water in order to simulate to use in technology through purifying and nickel/cobalt.Use close-fitting porcelain cap seal to close shredder, whole ore/acid mixtures were ground nearly 60 minutes, be lower than 100 orders up to most of solid particulate size.

According to the weight and the water capacity of ore sample, be 1.1 in the total saprolite/limonite ratio of dry product, total acid/ore ratio is 0.65 (with dry ore and 100%H ₂SO ₄Meter).

Then the content of shredder is expelled to embodiment 1 in used identical reactor.Use scalping to hold back grinding medium, use 30g/L Mg solution bulb syringe grinding machine and the grinding medium of 764g.Rinse solution is added in the reactor.

Reactor is heated to 95-100 ℃ and stirring.Carry out leaching in 24 hours.In preceding 5 hours of leaching, bubbling feeds sulfur dioxide gas with the oxidation reduction potential control (with respect to saturated Ag/AgCl reference electrode) between 540 to 600mV with slurry in leaching slurry.All gather slurry sample in the whole leaching process, filter, wash solid, solution and solid are analyzed.

When leaching process was finished, down to be neutralized to pH be 3.0 will leach slurry with the limestone slurry of adding 20% in leaching slurry in about 2 hours at 95 ℃.To the sampling of the leaching slurry after the neutralization, filter whole slurries then.

The result of leaching process is provided by table 9.

Table 9

Time (h)	[Ni]g/L	[Co]g/L	[Fe]g/L	[H 2SO 4]g/L
1	4.92	0.229	60.8	＜0.5
					2	5.33	0.248	50.0	＜0.5
4	6.22	0.290	33.9	＜0.5
					5	6.52	0.303	26.5	＜0.5
24	7.36	0.34	14.4	5.0

Solid analytical results when leaching process finishes is 0.21%Ni, 0.006%Co, 31.3%Fe, 0.65%Mg, 14.9%S i and 1.39%S.The extraction yield of Ni and Co (is supposed silicon not to be leached by " silicon constraint (silicontie) " method, use the analytical results of the silicon of ore and residue to calculate the weight that leaches residue, and use ore and residue weight and analytical results to calculate extraction yield) calculate, be about 93.1% and 95.5% respectively.The iron extraction yield is about 9%.

Be neutralized to after the pH3, the liquor analysis result is 6.23g/L Ni, 0.29g/L Co and 3.24g/L Fe.The solid analysis result is 0.22%Ni, 0.009%Co, 26.5%Fe and 11.7%Si.About 74% iron precipitates in N-process in the infusion solution; Therefore the clean extraction yield of neutralization back iron only has an appointment 2%, about 2% nickel and 4% cobalt in N-process with the iron co-precipitation.

This embodiment has illustrated some important feature of a kind of preferred implementation of the present invention: thus can directly obtain high nickel extraction yield by at first making sulfuric acid with limonite ore reaction and then adding saprolitic ores;---being sulfur dioxide gas in this example---can improve the cobalt extraction yield to add reductive agent in leaching slurry; Do not need to obtain high extraction by the slaking of acid/ore reaction mixture; Reaction between sulfuric acid and the ore is exceedingly fast and a large amount of heat release, makes can obtain very high temperature in acid/ore reaction process, thereby improves reaction power and make that the required equipment volume that is used to carry out the sulfation step is very little; Can after leaching, not exclusively neutralize with the major part in the iron of removing the small proportion that leaches, and make the loss minimum of nickel and cobalt leaching slurry.

Those skilled in the art will be appreciated that certainly present method can have multiple variation in broad range of the present invention, those skilled in the art will appreciate that basic the present invention of book can be by other the embodiment use that can realize the object of the invention and finish target of the present invention as an illustration.

Method of the present invention is widely used in both containing the nickel laterite body that limonite also contains saprolite, has comprised the great majority of laterite ore body.The saprolite of present method/limonite ratio can vary widely, as long as satisfy certain minimum value of saprolite/limonite ratio in the method.When for example using sulfuric acid, ferrous components by making " but sulfation " in limonite ore and the saprolitic ores generates some sulfuric acid with the form hydrolysis or the precipitation of ferric oxide compound or oxyhydroxide, and minimum ratio can roughly be determined in the saprolitic ores by calculating by the amount of the non-ferrous components of these sulfate sulfataseizations.Ratio can be any numerical value that is equal to or greater than this minimum value, as long as the add-on of acid is to calculate and get by aforesaid method, promptly be enough to limonite ore and saprolitic ores in can Sulfated non-ferrous components reaction the amount of acid add and be used for a small amount of soluble iron and be used to impel the excessive slightly amount of finishing of reacting.

More than disclosed content be in order to describe, and scope of the present invention is limited by following claim.

Claims (16)

1. a leaching contains the method for the laterite of limonite and saprolite, may further comprise the steps:

(a) limonite and saprolite are mixed with the dense mineral acid of capacity, with ore in the non-ferrous components of solubility form salt;

(b) at a certain temperature the mixture in the step (a) is carried out water logging and go out, extraction time is enough to make the hydrolysis of dissolved ferric iron, forms ferruginous throw out, is dissolved at least a in nickel and the cobalt in the infusion solution in a large number simultaneously; And

(c) from infusion solution, reclaim at least a in the compound of nickel or cobalt.

2. the process of claim 1 wherein and at first acid is mixed with limonite in the step (a), and then add saprolite.

3. claim 1 or 2 method, wherein with at least a portion fragmentation of ore to promote the uniform mixing of acid and ore.

4. the method for claim 2 is wherein broken separately with saprolitic ores, and then adds in the mixture of limonite and acid.

5. the process of claim 1 wherein limonite and saprolite common broken and grind and then mix with acid.

6. claim 1,2,4 or 5 described methods, wherein the water logging in the step (b) goes out in autoclave being up under about 150 ℃ temperature to carry out.

7. the described method of claim 6, wherein the water logging in the step (b) goes out in about 95-105 ℃ temperature range to carry out.

8. claim 1,2,4 or 5 described methods, wherein the water logging in the step (b) goes out in about 95-105 ℃ temperature range, carries out in the pressure range of about 15-70psia.

9. claim 4 or 5 method, wherein the water logging in the step (b) goes out to divide two stages to carry out, fs, under atmospheric pressure, carry out under the temperature of the boiling point that is up to infusion solution subordinate phase was carried out in autoclave, being up under about 150 ℃ temperature.

10. claim 4 or 5 method, wherein acid is selected from sulfuric acid, hydrochloric acid and nitric acid or its mixture.

11. the method for claim 8, wherein acid comprises vitriol for the salt that forms in sulfuric acid and the step (a).

12. claim 1,2,4 or 5 described methods, wherein the recovery of from infusion solution the compound of at least a nickel or cobalt being carried out in the step (c) comprises and adds ion exchange resin and do not carry out solid/liquid separation in advance in infusion solution.

13. claim 1,2,4 or 5 described methods are wherein at first separated infusion solution in the step (c) with throw out, and then reclaim the compound of at least a nickel or cobalt from infusion solution.

14. claim 1,2,4 or 5 described methods, wherein the water logging in step (b) goes out to add in the process reductive agent to strengthen the dissolving of cobalt in the ore.

15. the method for claim 14, wherein reductive agent is selected from sulfurous gas, hydrogen sulfide, solubility hydrosulphite and sulfite compound or soluble ferrous compound.

16. the method for claim 1 or 2 further comprises the step that the mixture in the step (a) is carried out slaking, and then the water logging of carrying out step (b) goes out.

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