CA1094817A - Hydrometallurgical recovery of metal values - Google Patents
Hydrometallurgical recovery of metal valuesInfo
- Publication number
- CA1094817A CA1094817A CA276,278A CA276278A CA1094817A CA 1094817 A CA1094817 A CA 1094817A CA 276278 A CA276278 A CA 276278A CA 1094817 A CA1094817 A CA 1094817A
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- metal bearing
- bearing source
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B23/00—Obtaining nickel or cobalt
- C22B23/005—Preliminary treatment of ores, e.g. by roasting or by the Krupp-Renn process
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B15/00—Obtaining copper
- C22B15/0002—Preliminary treatment
- C22B15/001—Preliminary treatment with modification of the copper constituent
- C22B15/0021—Preliminary treatment with modification of the copper constituent by reducing in gaseous or solid state
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B23/00—Obtaining nickel or cobalt
- C22B23/04—Obtaining nickel or cobalt by wet processes
- C22B23/0407—Leaching processes
- C22B23/0446—Leaching processes with an ammoniacal liquor or with a hydroxide of an alkali or alkaline-earth metal
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
- C22B3/12—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic alkaline solutions
- C22B3/14—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic alkaline solutions containing ammonia or ammonium salts
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B47/00—Obtaining manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B47/00—Obtaining manganese
- C22B47/0018—Treating ocean floor nodules
- C22B47/0045—Treating ocean floor nodules by wet processes
- C22B47/0054—Treating ocean floor nodules by wet processes leaching processes
- C22B47/0072—Treating ocean floor nodules by wet processes leaching processes with an ammoniacal liquor or with a hydroxide of an alkali or alkaline-earth metal
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Organic Chemistry (AREA)
- Metallurgy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Environmental & Geological Engineering (AREA)
- Geochemistry & Mineralogy (AREA)
- Ocean & Marine Engineering (AREA)
- Oceanography (AREA)
- Inorganic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In the hydrometallurgical recovery of metal values from ores and the like in which a metal bearing source is reduced in the presence of at least one additive at temperatures ranging from about 500° to about 900° C.
and thereafter extracted, the improvement which comprises pretreating only a portion of the feed stock with the additive prior to the reducing roast.
In the hydrometallurgical recovery of metal values from ores and the like in which a metal bearing source is reduced in the presence of at least one additive at temperatures ranging from about 500° to about 900° C.
and thereafter extracted, the improvement which comprises pretreating only a portion of the feed stock with the additive prior to the reducing roast.
Description
, ; BACKGROUND OF THE IN~ENTION
~ In the processing of materials containing metal values, two of the :
main extractive methods to be considered are pyrometallurgy and hydrometal-lurgy. In the former, metal-containing material such as ore, slag, scrap, etc., is heated with appropriate agents such as reducing agents, fluxing agents, sulfidizing agents, chloridizing agents and/or oxidlzing agents, etc., usually to the melting or fusion point of the mixture. At this tem-perature there is generally a~separation~of~metallic vdlues from gangue or waste materials. The procedure then calls~for separating the metallic values ~- 10 from slag or waste material at a temperature at which botb are molten. The `~ phase containing the metal value is then cast to;some convenient shape for use or for further refining, whichever is appropriate for the particular system involved. The very high temperatures involved in this technique are achieved via electric furnaces, blast furnaces, reverberatory furnaces, etc.
Temperatures reqùired for metals such as copper, nlckel, iron would gen-erally range from 2000 F. to 3000 F. An advantage in this method is that recoveries of the metal values are typically quite high.
1~948~L'7 The hydrometallurgy approach differs substantially from pyro-metallurgy in that, although the metal bearing materia1 such as ore, slag, scrap, etc., may be heated with agents such as reducing agents, oxidizing agents, sulfidizing and chloridizing agents as part of the procedure, the S temperatures involved are generally much lower than with the usual pyro-metallurgical method. These temperatures typically may be 500 F. to 1900 F., temperatures generally well below the fusion point of the metal-containing material.
~ollowing this step, the treated metal-containing material then is contacted with an appropriate aqueous soiution`for extracting metal values by dissolution. The metal is then removed from the solution by precipita-tion, solvent extraction, evaporation of solvent, etc. The metal-containing residue obtained is then handled appropriately to further refine the metal.
Although conditions of temperature are generally much lower than in pyro-i5 metallurgy, it is frequent1y found that recovery of the metal values is also lower than in the pyrometallurgical method.
A particular case where this is true concerns the extraction of nickel from lateritic nickel ores. The pyrometallurgical processes range from the use of an electric furnace for the direct smelting of ore to pro-duce ferronickei through similar techniques involving the blast furnace in which an iron-nickel-sulfide matte is obtained. The extraction of nicke1 from the ore using this method is greater than 90%.
Of the several hydrometallurgy approaches used commercially for treating this type of ore, the practice on a limonite ore or a highly serpentinic ore, such as that at Nicaro, Cuba, involves roasting the ore in a multihearth furnace while a reducing gas, such as producer gas, passes countercurrent to the ore. Temperatures in this case range from about fl817 900 F. to about 1350 F. Following the roasting step, the ore is cooled in the absence of air, mixed with an ammoniacal ammonium carbonate solution and vigorously agitated and aerated. This results in the dissolution of nickel and cobalt, separating them from the bulk of the ore. This solution then is treated with steam, driving off ammonia and precipitating nickel carbonate. This product then is treated further to obtain the appropriate form of nickel or use as such. In compar1son to the pyrometallurgical pro-cess, however, extractions using this method have only been of the order of 70 to 80 percent.
Several other hydrometallurgy methods involve the use of procedures which include a roasting step with chlorides or sulfates but in other than reducing atmospheres, and the roasted ore is leached with an appropriate solvent such as dilute sulfur1c acid. Alternatively, in certain cases the ore can be leached directly, such as with sulfuric acid solution but this 15 is practical only when the magnesia content of the ore is low.
The extraction of metal values from metal bearing sources may be ~; improved when the reductive roast is effected in the presence of certain additives such as added hydrogen halide, added sulfur, added sulfur-containing compounds or combinations of these additives. The add~tion of these addi-tives in which the metal bearing source 1s pretreated~with~the additive is known in the trade as a "pugging" step. Normally9~when utilizing a hydrogen halide, the pugging step introduces a large amount of water into the pro-cess and thus requires that expensive corrosion resistant mixing equipment be present. As will hereinafter be shown, it has now been discovered that only a minor portion of the metal bearing source which is the feed for the process need be contacted with the required amount of additive thereby permitting a sizable reduction of the amount of water which is required and ' concurrently permitting the use of less expensive corrosion resistant equipment. One means of accomplishlng this pug is to utilize this portion of the feed stock as a scrubbing medium for the offgases from the reductive roast of the ore.
SPECIFICATION
This invention relates to an improvement in the process for the - ~ obtention of metal values from metal bearing sources. More specifically, the invention is concerned with an improvement in a process for the re-covery of metal values from metal bear;ng sources in which the pretreatment of the metal bearing source prior to a reductive roast is effected by con-tacting only a portion of the feed with an additivs, said additive being used to improve the recovery of the desired metal value.
,- :
As hereinbefore set forth, the hydrometallurgical extraction of metal values has been found to be improved when the reductive roast of the - metal bearing~source is effected in the presence of additives comprising added hydrogen halide, added solid sulfur, added sulfur-containing com-~ ~ , pounds or combinations thereof. ~hile the exact reasons for ~he improved results or the mechanism by which they are accomplished are not known, several explanations therefor may be offered, with the understanding that the applicants do not intend to be limited thereto. One explanation is that the additives may act to reduce or ~o facilitate reduction of the com-bined m~tal or to otherwise assist in liberating the metal, whereby it is . ~
readily extractabl~e. Another explanatlon ls thdt the comb;nation of addi-tives may act or facilitate such action to reduce the nickel ;n an iron-nickel alloy to thereby convert the nickel into a readily extractable form.
Still another explanation lS that the combination of additives may act to :
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1~394~
prevent recombination of the metal into a form in which it is less readily extractable.
It is recognized that different ores respond differently to dif-ferent additives and that greater improvement in the recovery of metal values may be obtalned with some ores when the roasting is conducted in contact with a mixture of added gaseous sulfur compound and added sulfur or in con-tact with added gaseous sulfur compound and added hydrogen halide or when the roasting is effected in contact with all three of these additives.
Also, it is recognized that some added gaseous sulfur compounds will respond differently in this system than other added yaseous sulfur compounds. Accord-ingly, the specific added gaseous sulfur compound and added sulfur and/or added hydrogen halide will be selected with reference to the particular ore to be processed.
As hereinbefore set forth, improved recovery of metal values is obtained when the roasting of the metal-conta~ning material such as ore, slag~ scrap, etc., is effected in contact with additives such as gaseous ; sulfur compounds, added solid sulfur, and/or added hydrogen halide, whereby the recovery of the metal value is effected in a considerably higher yield than heretofore obtained in the hydrometallurgical system.
The process of the present invention may be used for the recovery of metal values from ore, slag, scrap or other metal bearing source and is particularly applicable to the recovery of nickel from such sources. How-ever, it is to be und~rstood ~hat the process may be used for the recovery of other metal values includlng, for example, cobalt~ copper, manganese and other metals which are soluble in ammoniacal ammonium carbonate solu-tions, but not necessarily with equivalent results. In the interest of ~48~L~
brevity, the following discussion will be directed to the recovery of nickel, with the understanding that it may be applied to the recovery of other metals as hereinbefore set forth.
As another advantage to the present invention, the process may be conducted in conventional apparatus and may utilize much of the conventional steps of prior art processes. Accordingly, the ore such as a lateritic nickel ore or other metal bearing source is prepared in a manner suitable for the process, such as finely divided or comminuted particles in a con-ventional way. The particles may be within a size range of from about 8 mesh to about 500 mesh or smaller and preferably within a range of from about 48 mesh to about 200 mesh. The partlcles then preferably are dried in a conventional manner to lower the molsture content of from about the usual 25% to 50% down to about 8% or 10% or iess. The drying generally is e~fected in a rotary kiln at con~entional temperatures.
The added gaseous sulfur compound will be used in a sufficient concentration for the purpose and may be wlthin the range of from about 0.01% to about 10% and preferably from about 0.1% to about 5% by weight of the ore. Any suitable gaseous sulfur compound may be used in the present invention. Preferred gaseous sulfur compounds comprise hydrogen ; 20 sulfide, sulfur dioxide, sulfur trioxide, carbonyl sulfide, carbon mono-sulfide, carbon disulfide, etc. For ease of use, the added gaseous sulfur compound preferably is normally gaseous. However, in another embodiment it may be normally 1i4uid and vaporized prior tQ use or allowed to vapori~e under the conditions existing in the reduc~ng zone. In another embodiment the added sulfur compound is a hydrocarbyl sulflde including, for example, methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl n~rcaptan, pentyl mercaptan, hexyl mercaptan, etc., but generally containing not more than about 20 carbon atoms per molecule. The solid sulfur which may be used will be in solid forms including powder, flour, granules, pellets, etc., or as molten or as otherwise liquefied sulfur or as sulfur vapors. Generally speaking, the sulfur is employed in a concentration of from about 0.01% to about 5% and preferably from about 0.15% to about 3% by weight of the ore.
When the additive comprises a hydrogen halide, the hydrogen halide is used in a concentration of from about 0.01% to about 10~ and preferably from about 0.1% to about 5% by weight of the ore. Any hydrogen halide gas nlay be used and preferably comprises hydrogen chloride or hydrogen bromide.
It is also contemplated within the scope of this invention that hydrogen iodide or hydrogen fluori~e may also be employed but not necessarily with :
equivalent results. In still another embcdiment a precursor of hydrogen halide may be used and may be selected from free halogen, chlorine, bromine, iodine, fluorine or other suitable compounds selected from boron halides, carbon halides~ phosphorus halides, silicon halides, etc. In still another embodiment, the precursor may comprise a hydrocarbon halide wnich preferably contains not more than about 20 carbon atoms per molecule.
It is therefore an ob~ect of this invention to provide an improved - process for the recovery of metal values from a metal bearing source by uti-lizing only a minor portion of the feedstock to be contacted with the addi-tive or combination of additives prior to admixture with the remaining portion of the feedstock, the total feedstock being thereafter sub~ected to the reductive roast and extraction step.
A further object of this invention ls found in an improvement in ; 2S the process for effecting the recovery of metal values from a metal bearing source by utilizing only a minor portion of the metal bearing source feed-stock in a scrubber unit to recover additives in the offgases recovered from thé reductive roasting step of the process.
~ID9'a!3~L7 In one aspect an embodiment of this in~ention resides in a process for the recovery of metal values from a metal bearing source wherein said metal bearing source is subjected to a roast in a reducing atmosphere at a temperature in the range of from about 550 to about 900 C. in contact with at least one additive~ cooling the metal bearing source9 extracting the cooled metal bearing source, and recovering the desired metal valuej the improvement which comprises pretreating a minor portion of said rnetal bearing source with said additive and thereafter ad-mixing said treated minor portion of said metal bearing source with the remainder of said metal bearing source prior to the reduction thereot.
A specific embodiment of this invention is found ina process for the recovery of metal values from a metal bearing source wherein said metal bearing source is subjected to a roast in a reducing atmosphere at a tem-perature of from about 550 to about 900 C. in contact with hydrochloric acid, cooling the metal bearing source, extracting the cooled metal bearing source and recoYering the desired metal value,~the improvement which com-prises pretreating a minor portion of said metal~bearing source with the hydrochlorlc acid which has been regenerated from the roast of said metal bearing source a~nd recycled by contact with the minor portion of said ~ 20 metal bearing source.
; ~ Other objects and embodiments w111 b found in the following further detailed description of the pr~sent invention.
As hereinbefore set forth it has now been discovered that the - aforesaid additives may be admixed with only a minor porti~n of the total metal bearing source feedstock prior to the reduction of the metal bearing source. In one embodiment of the inven~ion, a portion of the aforesaid , ~ metal bearing source which is utilized as the feedstock after undergoing .
~ -8-~0~ L7 partial drying is charged to a scrubber recycle tank. In this scrubber unit, the ore feed, in slurry form, is contacted with the additive sùch as the hydrogen halide or sulfur-containing compound which has been regenerated from the roasting step of the operation which will hereinafter be described in a more detailed manner. The gases which have been regenerated from the calcination or roasting step will comprise a mixture nf the additives such ; as hydrogen chloride, hydrogen bromide, hydrogen sulfide, etc., plus carbon monoxide, carbon dioxide, other sulfur forms, nitrogen, hydrogen and water vapor. These gases are passed to a scrubber wherein they may be contacted with an aqueous slurry of a minor portion of the ore feed and the additives are separated therefrom. As hereinbefore set forth, this minor portion of-the ore feed may comprise from about 1~ to about 49% of the total feed, the usual amount comprising from about 10 to about 20% of the feed. In the event that the additives which are employed to facilitate the recovery of lS the metal bearing values from the metal bearing source comprise a mixture of both a hydrogen halide and a sulfur-containing compound, it is contem-plated withln the scope of this invention that the contact of the minor portion of the feedstock with the additives may be effected in two scrubber ; units. For example, when the combination of additives comprises a mixture of hydrogen chloride and sulfur or a sulfur-containing compound such as hydrogen sulfide~ the minor portion of the feedstock may be passed to one scrubber means wherein it is contacted with the hydrogen halide. There-after a second part of the minor portion of the metal bearing source is contacted with sulfur or a sulfur-containing compound in a second scrubber 1 25 means and preferably in the presence of an added alkaline compound in order to insure that the pH of the mlxture is in the alkaline rather than in the acid range. Examples of alkaline compounds which may be utilized in ~;,',' , ~
: g ~; , ,~ ' 8~7 admixture with the sulfur-containing compound will include sodium hydroxide, potassium hydroxide~ lithium hydroxide, calcium hydroxide, magnesium hy-droxide, the corresponding carbonates, etc. The amount of alkaline com-pound which is used will vary over a relatively wide range and be sufficient, as hereinbefore set forth, to maintain an alkaline range in the scrubber means. The two parts of the minor portion are then combined and thereafter admixed with the major portion of the metal bearing source prior to roasting or calcination.
In an alternative method of effecting the process of tne present invention, the minor portion of the metal bearing source in a range herein-before set forth may be subjected to a drying step at a temperature in the range of from about 250 to about 350 C. and thereafter contacted with the additive which is added in a fresh feed rather than haVing been recycled from the calcination or roasting step. When this method of addition is ; 15 effected utilizing more than one additive, one part of the minor portion of the metal bearing source is contacted with the sulfur containing com-pound of the type hereinbefore set forth in greater detail while a second part of the minor portion of the metal bearing source is contacted with the hydrogen halide. Thereafter tne two parts are combined and admixed with the major portion of the metal bearing source which is then charged to the calcination apparatus.
:
The feedstock which has been pretreated with the additives is then supplied to a suitable reducing zone which may be of conventional design including, for example, a multiple hearth furnace, fluosolids roaster, etc.
The chem;cal reduction of the ore is effected by means of a suitable reducing gas mixture which, here again, is of the general type used in ~ -10-conventional processes. Any suitable reducing gas mixture may be used and preferably comprises a mixture of hydrogen, carbon monoxide, carbon di-oxide and water vapor. The gas mixture may come from any suitable source, including producer gas~ gases formed by the combustion of city gas, gases formed by combustion of oil. etc. The specific gas mixture will be selected to effect the desired reduction. An illustrative gas mixture comprises a CO:C02 ratio within the range of about 0.1:1 to lO:l, a CO:H2 ratio of about 0.1:1 to 10:1 and a H2:H20 vapor ratio of about 0.1:1 to lO:l, all being on a volumetric basis. In one embodiment, it is des~rable to main-tain the gas ~ixture within the ratios set forth above because an excessive concentration of one or more of the components in the gas m~xture may have undesired effects such as, for example, incomplete reduction of the metal compound, excessive adsorption of the gas in the ore particles, etc. It is understood that the gas mixture may conta~n other cnmponents as, for l~ example, nitrogen, when advantages appear therefor. Another illustrative gas mixture comprises hydrogen, nitrogen and water vapor. Still another gas mixture may compr~se natural gas or a g2s such as carbon monoxide may be employed.
As hereinbefore set forth, the reduct~on of the metal compounds to the free metal is effected at a temperature of from about 540 to about ':
950 C. and preferably from about 650 to about 850 C. ~he low temperature utilized in the reduct1On avoids the objections inherent in the prior art high temperature reduction processes. Also, as hereinbefore set forth, the ; reduction is effected in a short time and this further constitutes another advantage to the novel method of the present invention.
As hereinbefore set forth, the gaseous sulfur compounds and the hydrogen ha1ides may be recycled for use as additlves in contact~ng a minor 8~7 portion of the feedstock prior to the roasting step. For example, the gases which are withdrawn from the reducing zone may be passed to a low energy scrubber wherein they are contacted with an additional amount of water, the additives being separated from the offgas and utilized in a manner hereinbefore set forth. Alternatively the gases leavlng the reducing zone may be suitably treated as, for example, by adsorption on a solid ad-sorbent and desorption with a suitable desorbing gas, absorption in a suitable solvent followed by a release utilizing stripping, flashing, or other~sultable methods whereby these components may be recovered for re-~10 cycling within the system.
The reduced ore particles are withdrawn from the reducing zone and then processed in conventional manner for the hydrometallurgical ex-traction of the nickel. Thè effluent from the reduction zone is first cooled several hundred degrees and then is passed into one or more quench zones.
15~ In a preferred embodiment the quench liquid is the ammonium carbonate , :
leaching solution. However, the~quenching must be effected in the absence of air. In other words, oxygen or air should `not contact the reduced particles until the temperature of the particles is below about 95 C. because of the poss~ibility of oxidation-of the me~tal to the oxide or to other oxygen-con-taining compounds. It is understood that other suitable~quenching solutions may be employed but, as hereinbefoie set forth, economical advantages appear " ~ for`the use of the leaching solution.
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Any suitable leaching sol~ution may be employed and preferably comprises aqueous ammon~um carbonate solution containing from about 2% to . ;~ .
about 25% and preferably from about 3% to about 15b NH3 and from about 1%
~`~ to about 15% and preferably from about 1.5% to about 7.5% C02. As still another advantage to the process of the present lnvention, the leaching 8~L7 solution comprises a lower concentration of NH3 than generally is utilized ln the prior art, thus effecting an additional economy in the present pro-cess. The leaching is effected at a temperature below 95 C. and conveniently ambient temperature. Ambient pressure or superatmospheric pressure may be used but generally will not exceed about 100 psig. As hereinbefore set forth, the leaching is effected in the presence of oxygen, whirh may com-prise ambient air when the leaching is effected in open tanks or vessels or it may comprise air introduced into closed zones. It is understood that, in the place of air, oxygen or other suitable oxygen-containing source may ; 10 be utilized.
After reduction in the presence of the additives such as the gaseous sulfur compound, solid sulfur and/or hydrogen halide which facili-tates the extraction of the nickel and particularly the separation thereof from iron or iron compounds, the mixture is extracted by any suitable man-- lS ner and generally by passing the ore countercurrently to the leaching solution in a plurality of leaching and thickening zones.
~ The solution of nickel which is withdrawn from the leaching and ;~ thickening zones is then treated in any suitable manner to precipitate the nickel and recover the same. In one method, this is accomplished b-y steam-. 20 ing whereby~the nickel carbonate is prec1pitated and the ammonia, carbon di-` ~ oxide and water are volatillzed. Thereafter the precipitated nickel carbonate can be treated in any conventional manner to~recover the desired metal.
The following examples are given to illustrate the process of ~; the present invention. However~ it is to be understood that these examples ~5 are given merely for purposes of illustration and are not intended to limit the generally broad scope of the present invention in strict accordance therewith.
., `
-EXAMPLE_I
A series of expertmental runs to illustrate the operability of the process of the present invention was made using a lateritic nickel ore which had the follow~ng assay:
Nickel 1.75~
Cobalt0.072%
: Iron 25.7%
Magnesium 2.4~
Chromium l.O9X
Silica42.4%
The sample of the ore was ground to less than 65 mesh and utîlized by admixing 200 grams of a total charge of 1000 grams with 200 cc of a 15% hydrogen chlo-. ~ ride solution9 the mixture being allowed to interact for a period of 2 hours. The result;ng slurry was~then blended with 800 grams of additional dry ore and mixed with 20 grams of sulfur as pyrite. The resulting blend was then roasted in a fluid~bed reactor at a temperature oF 700 C. for 15 minutes under reducing conditions as provided for by a~producer gas type ... .
~; mixture containing carbon monoxide, hydrogen~, nitrogen, carbon dioxide and ` ~ water. After being treated in this manner the reduced ore was recovered ~:~ 20 and slurried with an ammoniacal ammonium carbonate solution. The slurry was agitated vigorously at amblent temperature for about 2.5 hours and there^
after filtered. The filtrate was then assayed for nickel content to deter-~: mlne the percent extractlon, said extraction amounting to 92.1%.
In contrast to this extraction procedure when the ore was reduced in a similar manner followed by extraction with an ammoniacal ammonium car-bonate solution without having been pretreated with hydrogen chloride and a sulfur-containing compound, it was found that only 28.7X of the nickel had bPen extracted.
.
~0~ 7 EXAMPLE II
In this example a lateritic nickel ore having the same composi-tion as that set forth in Example I above was treated in a normal manner by admixing the ore with aqueous hydrogen chloride and pyrite at an amount so that there was 4.6% hydrogen chloride and 2% sulfur present ln the mix-ture. The mix was then reductively roasted at a temperature of about 700 C.
at a rate of 7 pounds per hour in ar, externally heated tube reactor uti-lizing a rotating screw to convey the ore through the hot zone. The roast was effected in the presence of a producer gas type mixture containing ~; 10 carbon monoxide, carbon dioxide, hydrogen, nitrogen and water, the retention ; time of the hot zone being about 45 minutes.
The reduced ore was then slurried with an ammoniacal ammonium car-bonate solution and agitated at amblent temperature for a period of about
~ In the processing of materials containing metal values, two of the :
main extractive methods to be considered are pyrometallurgy and hydrometal-lurgy. In the former, metal-containing material such as ore, slag, scrap, etc., is heated with appropriate agents such as reducing agents, fluxing agents, sulfidizing agents, chloridizing agents and/or oxidlzing agents, etc., usually to the melting or fusion point of the mixture. At this tem-perature there is generally a~separation~of~metallic vdlues from gangue or waste materials. The procedure then calls~for separating the metallic values ~- 10 from slag or waste material at a temperature at which botb are molten. The `~ phase containing the metal value is then cast to;some convenient shape for use or for further refining, whichever is appropriate for the particular system involved. The very high temperatures involved in this technique are achieved via electric furnaces, blast furnaces, reverberatory furnaces, etc.
Temperatures reqùired for metals such as copper, nlckel, iron would gen-erally range from 2000 F. to 3000 F. An advantage in this method is that recoveries of the metal values are typically quite high.
1~948~L'7 The hydrometallurgy approach differs substantially from pyro-metallurgy in that, although the metal bearing materia1 such as ore, slag, scrap, etc., may be heated with agents such as reducing agents, oxidizing agents, sulfidizing and chloridizing agents as part of the procedure, the S temperatures involved are generally much lower than with the usual pyro-metallurgical method. These temperatures typically may be 500 F. to 1900 F., temperatures generally well below the fusion point of the metal-containing material.
~ollowing this step, the treated metal-containing material then is contacted with an appropriate aqueous soiution`for extracting metal values by dissolution. The metal is then removed from the solution by precipita-tion, solvent extraction, evaporation of solvent, etc. The metal-containing residue obtained is then handled appropriately to further refine the metal.
Although conditions of temperature are generally much lower than in pyro-i5 metallurgy, it is frequent1y found that recovery of the metal values is also lower than in the pyrometallurgical method.
A particular case where this is true concerns the extraction of nickel from lateritic nickel ores. The pyrometallurgical processes range from the use of an electric furnace for the direct smelting of ore to pro-duce ferronickei through similar techniques involving the blast furnace in which an iron-nickel-sulfide matte is obtained. The extraction of nicke1 from the ore using this method is greater than 90%.
Of the several hydrometallurgy approaches used commercially for treating this type of ore, the practice on a limonite ore or a highly serpentinic ore, such as that at Nicaro, Cuba, involves roasting the ore in a multihearth furnace while a reducing gas, such as producer gas, passes countercurrent to the ore. Temperatures in this case range from about fl817 900 F. to about 1350 F. Following the roasting step, the ore is cooled in the absence of air, mixed with an ammoniacal ammonium carbonate solution and vigorously agitated and aerated. This results in the dissolution of nickel and cobalt, separating them from the bulk of the ore. This solution then is treated with steam, driving off ammonia and precipitating nickel carbonate. This product then is treated further to obtain the appropriate form of nickel or use as such. In compar1son to the pyrometallurgical pro-cess, however, extractions using this method have only been of the order of 70 to 80 percent.
Several other hydrometallurgy methods involve the use of procedures which include a roasting step with chlorides or sulfates but in other than reducing atmospheres, and the roasted ore is leached with an appropriate solvent such as dilute sulfur1c acid. Alternatively, in certain cases the ore can be leached directly, such as with sulfuric acid solution but this 15 is practical only when the magnesia content of the ore is low.
The extraction of metal values from metal bearing sources may be ~; improved when the reductive roast is effected in the presence of certain additives such as added hydrogen halide, added sulfur, added sulfur-containing compounds or combinations of these additives. The add~tion of these addi-tives in which the metal bearing source 1s pretreated~with~the additive is known in the trade as a "pugging" step. Normally9~when utilizing a hydrogen halide, the pugging step introduces a large amount of water into the pro-cess and thus requires that expensive corrosion resistant mixing equipment be present. As will hereinafter be shown, it has now been discovered that only a minor portion of the metal bearing source which is the feed for the process need be contacted with the required amount of additive thereby permitting a sizable reduction of the amount of water which is required and ' concurrently permitting the use of less expensive corrosion resistant equipment. One means of accomplishlng this pug is to utilize this portion of the feed stock as a scrubbing medium for the offgases from the reductive roast of the ore.
SPECIFICATION
This invention relates to an improvement in the process for the - ~ obtention of metal values from metal bearing sources. More specifically, the invention is concerned with an improvement in a process for the re-covery of metal values from metal bear;ng sources in which the pretreatment of the metal bearing source prior to a reductive roast is effected by con-tacting only a portion of the feed with an additivs, said additive being used to improve the recovery of the desired metal value.
,- :
As hereinbefore set forth, the hydrometallurgical extraction of metal values has been found to be improved when the reductive roast of the - metal bearing~source is effected in the presence of additives comprising added hydrogen halide, added solid sulfur, added sulfur-containing com-~ ~ , pounds or combinations thereof. ~hile the exact reasons for ~he improved results or the mechanism by which they are accomplished are not known, several explanations therefor may be offered, with the understanding that the applicants do not intend to be limited thereto. One explanation is that the additives may act to reduce or ~o facilitate reduction of the com-bined m~tal or to otherwise assist in liberating the metal, whereby it is . ~
readily extractabl~e. Another explanatlon ls thdt the comb;nation of addi-tives may act or facilitate such action to reduce the nickel ;n an iron-nickel alloy to thereby convert the nickel into a readily extractable form.
Still another explanation lS that the combination of additives may act to :
.
1~394~
prevent recombination of the metal into a form in which it is less readily extractable.
It is recognized that different ores respond differently to dif-ferent additives and that greater improvement in the recovery of metal values may be obtalned with some ores when the roasting is conducted in contact with a mixture of added gaseous sulfur compound and added sulfur or in con-tact with added gaseous sulfur compound and added hydrogen halide or when the roasting is effected in contact with all three of these additives.
Also, it is recognized that some added gaseous sulfur compounds will respond differently in this system than other added yaseous sulfur compounds. Accord-ingly, the specific added gaseous sulfur compound and added sulfur and/or added hydrogen halide will be selected with reference to the particular ore to be processed.
As hereinbefore set forth, improved recovery of metal values is obtained when the roasting of the metal-conta~ning material such as ore, slag~ scrap, etc., is effected in contact with additives such as gaseous ; sulfur compounds, added solid sulfur, and/or added hydrogen halide, whereby the recovery of the metal value is effected in a considerably higher yield than heretofore obtained in the hydrometallurgical system.
The process of the present invention may be used for the recovery of metal values from ore, slag, scrap or other metal bearing source and is particularly applicable to the recovery of nickel from such sources. How-ever, it is to be und~rstood ~hat the process may be used for the recovery of other metal values includlng, for example, cobalt~ copper, manganese and other metals which are soluble in ammoniacal ammonium carbonate solu-tions, but not necessarily with equivalent results. In the interest of ~48~L~
brevity, the following discussion will be directed to the recovery of nickel, with the understanding that it may be applied to the recovery of other metals as hereinbefore set forth.
As another advantage to the present invention, the process may be conducted in conventional apparatus and may utilize much of the conventional steps of prior art processes. Accordingly, the ore such as a lateritic nickel ore or other metal bearing source is prepared in a manner suitable for the process, such as finely divided or comminuted particles in a con-ventional way. The particles may be within a size range of from about 8 mesh to about 500 mesh or smaller and preferably within a range of from about 48 mesh to about 200 mesh. The partlcles then preferably are dried in a conventional manner to lower the molsture content of from about the usual 25% to 50% down to about 8% or 10% or iess. The drying generally is e~fected in a rotary kiln at con~entional temperatures.
The added gaseous sulfur compound will be used in a sufficient concentration for the purpose and may be wlthin the range of from about 0.01% to about 10% and preferably from about 0.1% to about 5% by weight of the ore. Any suitable gaseous sulfur compound may be used in the present invention. Preferred gaseous sulfur compounds comprise hydrogen ; 20 sulfide, sulfur dioxide, sulfur trioxide, carbonyl sulfide, carbon mono-sulfide, carbon disulfide, etc. For ease of use, the added gaseous sulfur compound preferably is normally gaseous. However, in another embodiment it may be normally 1i4uid and vaporized prior tQ use or allowed to vapori~e under the conditions existing in the reduc~ng zone. In another embodiment the added sulfur compound is a hydrocarbyl sulflde including, for example, methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl n~rcaptan, pentyl mercaptan, hexyl mercaptan, etc., but generally containing not more than about 20 carbon atoms per molecule. The solid sulfur which may be used will be in solid forms including powder, flour, granules, pellets, etc., or as molten or as otherwise liquefied sulfur or as sulfur vapors. Generally speaking, the sulfur is employed in a concentration of from about 0.01% to about 5% and preferably from about 0.15% to about 3% by weight of the ore.
When the additive comprises a hydrogen halide, the hydrogen halide is used in a concentration of from about 0.01% to about 10~ and preferably from about 0.1% to about 5% by weight of the ore. Any hydrogen halide gas nlay be used and preferably comprises hydrogen chloride or hydrogen bromide.
It is also contemplated within the scope of this invention that hydrogen iodide or hydrogen fluori~e may also be employed but not necessarily with :
equivalent results. In still another embcdiment a precursor of hydrogen halide may be used and may be selected from free halogen, chlorine, bromine, iodine, fluorine or other suitable compounds selected from boron halides, carbon halides~ phosphorus halides, silicon halides, etc. In still another embodiment, the precursor may comprise a hydrocarbon halide wnich preferably contains not more than about 20 carbon atoms per molecule.
It is therefore an ob~ect of this invention to provide an improved - process for the recovery of metal values from a metal bearing source by uti-lizing only a minor portion of the feedstock to be contacted with the addi-tive or combination of additives prior to admixture with the remaining portion of the feedstock, the total feedstock being thereafter sub~ected to the reductive roast and extraction step.
A further object of this invention ls found in an improvement in ; 2S the process for effecting the recovery of metal values from a metal bearing source by utilizing only a minor portion of the metal bearing source feed-stock in a scrubber unit to recover additives in the offgases recovered from thé reductive roasting step of the process.
~ID9'a!3~L7 In one aspect an embodiment of this in~ention resides in a process for the recovery of metal values from a metal bearing source wherein said metal bearing source is subjected to a roast in a reducing atmosphere at a temperature in the range of from about 550 to about 900 C. in contact with at least one additive~ cooling the metal bearing source9 extracting the cooled metal bearing source, and recovering the desired metal valuej the improvement which comprises pretreating a minor portion of said rnetal bearing source with said additive and thereafter ad-mixing said treated minor portion of said metal bearing source with the remainder of said metal bearing source prior to the reduction thereot.
A specific embodiment of this invention is found ina process for the recovery of metal values from a metal bearing source wherein said metal bearing source is subjected to a roast in a reducing atmosphere at a tem-perature of from about 550 to about 900 C. in contact with hydrochloric acid, cooling the metal bearing source, extracting the cooled metal bearing source and recoYering the desired metal value,~the improvement which com-prises pretreating a minor portion of said metal~bearing source with the hydrochlorlc acid which has been regenerated from the roast of said metal bearing source a~nd recycled by contact with the minor portion of said ~ 20 metal bearing source.
; ~ Other objects and embodiments w111 b found in the following further detailed description of the pr~sent invention.
As hereinbefore set forth it has now been discovered that the - aforesaid additives may be admixed with only a minor porti~n of the total metal bearing source feedstock prior to the reduction of the metal bearing source. In one embodiment of the inven~ion, a portion of the aforesaid , ~ metal bearing source which is utilized as the feedstock after undergoing .
~ -8-~0~ L7 partial drying is charged to a scrubber recycle tank. In this scrubber unit, the ore feed, in slurry form, is contacted with the additive sùch as the hydrogen halide or sulfur-containing compound which has been regenerated from the roasting step of the operation which will hereinafter be described in a more detailed manner. The gases which have been regenerated from the calcination or roasting step will comprise a mixture nf the additives such ; as hydrogen chloride, hydrogen bromide, hydrogen sulfide, etc., plus carbon monoxide, carbon dioxide, other sulfur forms, nitrogen, hydrogen and water vapor. These gases are passed to a scrubber wherein they may be contacted with an aqueous slurry of a minor portion of the ore feed and the additives are separated therefrom. As hereinbefore set forth, this minor portion of-the ore feed may comprise from about 1~ to about 49% of the total feed, the usual amount comprising from about 10 to about 20% of the feed. In the event that the additives which are employed to facilitate the recovery of lS the metal bearing values from the metal bearing source comprise a mixture of both a hydrogen halide and a sulfur-containing compound, it is contem-plated withln the scope of this invention that the contact of the minor portion of the feedstock with the additives may be effected in two scrubber ; units. For example, when the combination of additives comprises a mixture of hydrogen chloride and sulfur or a sulfur-containing compound such as hydrogen sulfide~ the minor portion of the feedstock may be passed to one scrubber means wherein it is contacted with the hydrogen halide. There-after a second part of the minor portion of the metal bearing source is contacted with sulfur or a sulfur-containing compound in a second scrubber 1 25 means and preferably in the presence of an added alkaline compound in order to insure that the pH of the mlxture is in the alkaline rather than in the acid range. Examples of alkaline compounds which may be utilized in ~;,',' , ~
: g ~; , ,~ ' 8~7 admixture with the sulfur-containing compound will include sodium hydroxide, potassium hydroxide~ lithium hydroxide, calcium hydroxide, magnesium hy-droxide, the corresponding carbonates, etc. The amount of alkaline com-pound which is used will vary over a relatively wide range and be sufficient, as hereinbefore set forth, to maintain an alkaline range in the scrubber means. The two parts of the minor portion are then combined and thereafter admixed with the major portion of the metal bearing source prior to roasting or calcination.
In an alternative method of effecting the process of tne present invention, the minor portion of the metal bearing source in a range herein-before set forth may be subjected to a drying step at a temperature in the range of from about 250 to about 350 C. and thereafter contacted with the additive which is added in a fresh feed rather than haVing been recycled from the calcination or roasting step. When this method of addition is ; 15 effected utilizing more than one additive, one part of the minor portion of the metal bearing source is contacted with the sulfur containing com-pound of the type hereinbefore set forth in greater detail while a second part of the minor portion of the metal bearing source is contacted with the hydrogen halide. Thereafter tne two parts are combined and admixed with the major portion of the metal bearing source which is then charged to the calcination apparatus.
:
The feedstock which has been pretreated with the additives is then supplied to a suitable reducing zone which may be of conventional design including, for example, a multiple hearth furnace, fluosolids roaster, etc.
The chem;cal reduction of the ore is effected by means of a suitable reducing gas mixture which, here again, is of the general type used in ~ -10-conventional processes. Any suitable reducing gas mixture may be used and preferably comprises a mixture of hydrogen, carbon monoxide, carbon di-oxide and water vapor. The gas mixture may come from any suitable source, including producer gas~ gases formed by the combustion of city gas, gases formed by combustion of oil. etc. The specific gas mixture will be selected to effect the desired reduction. An illustrative gas mixture comprises a CO:C02 ratio within the range of about 0.1:1 to lO:l, a CO:H2 ratio of about 0.1:1 to 10:1 and a H2:H20 vapor ratio of about 0.1:1 to lO:l, all being on a volumetric basis. In one embodiment, it is des~rable to main-tain the gas ~ixture within the ratios set forth above because an excessive concentration of one or more of the components in the gas m~xture may have undesired effects such as, for example, incomplete reduction of the metal compound, excessive adsorption of the gas in the ore particles, etc. It is understood that the gas mixture may conta~n other cnmponents as, for l~ example, nitrogen, when advantages appear therefor. Another illustrative gas mixture comprises hydrogen, nitrogen and water vapor. Still another gas mixture may compr~se natural gas or a g2s such as carbon monoxide may be employed.
As hereinbefore set forth, the reduct~on of the metal compounds to the free metal is effected at a temperature of from about 540 to about ':
950 C. and preferably from about 650 to about 850 C. ~he low temperature utilized in the reduct1On avoids the objections inherent in the prior art high temperature reduction processes. Also, as hereinbefore set forth, the ; reduction is effected in a short time and this further constitutes another advantage to the novel method of the present invention.
As hereinbefore set forth, the gaseous sulfur compounds and the hydrogen ha1ides may be recycled for use as additlves in contact~ng a minor 8~7 portion of the feedstock prior to the roasting step. For example, the gases which are withdrawn from the reducing zone may be passed to a low energy scrubber wherein they are contacted with an additional amount of water, the additives being separated from the offgas and utilized in a manner hereinbefore set forth. Alternatively the gases leavlng the reducing zone may be suitably treated as, for example, by adsorption on a solid ad-sorbent and desorption with a suitable desorbing gas, absorption in a suitable solvent followed by a release utilizing stripping, flashing, or other~sultable methods whereby these components may be recovered for re-~10 cycling within the system.
The reduced ore particles are withdrawn from the reducing zone and then processed in conventional manner for the hydrometallurgical ex-traction of the nickel. Thè effluent from the reduction zone is first cooled several hundred degrees and then is passed into one or more quench zones.
15~ In a preferred embodiment the quench liquid is the ammonium carbonate , :
leaching solution. However, the~quenching must be effected in the absence of air. In other words, oxygen or air should `not contact the reduced particles until the temperature of the particles is below about 95 C. because of the poss~ibility of oxidation-of the me~tal to the oxide or to other oxygen-con-taining compounds. It is understood that other suitable~quenching solutions may be employed but, as hereinbefoie set forth, economical advantages appear " ~ for`the use of the leaching solution.
;
Any suitable leaching sol~ution may be employed and preferably comprises aqueous ammon~um carbonate solution containing from about 2% to . ;~ .
about 25% and preferably from about 3% to about 15b NH3 and from about 1%
~`~ to about 15% and preferably from about 1.5% to about 7.5% C02. As still another advantage to the process of the present lnvention, the leaching 8~L7 solution comprises a lower concentration of NH3 than generally is utilized ln the prior art, thus effecting an additional economy in the present pro-cess. The leaching is effected at a temperature below 95 C. and conveniently ambient temperature. Ambient pressure or superatmospheric pressure may be used but generally will not exceed about 100 psig. As hereinbefore set forth, the leaching is effected in the presence of oxygen, whirh may com-prise ambient air when the leaching is effected in open tanks or vessels or it may comprise air introduced into closed zones. It is understood that, in the place of air, oxygen or other suitable oxygen-containing source may ; 10 be utilized.
After reduction in the presence of the additives such as the gaseous sulfur compound, solid sulfur and/or hydrogen halide which facili-tates the extraction of the nickel and particularly the separation thereof from iron or iron compounds, the mixture is extracted by any suitable man-- lS ner and generally by passing the ore countercurrently to the leaching solution in a plurality of leaching and thickening zones.
~ The solution of nickel which is withdrawn from the leaching and ;~ thickening zones is then treated in any suitable manner to precipitate the nickel and recover the same. In one method, this is accomplished b-y steam-. 20 ing whereby~the nickel carbonate is prec1pitated and the ammonia, carbon di-` ~ oxide and water are volatillzed. Thereafter the precipitated nickel carbonate can be treated in any conventional manner to~recover the desired metal.
The following examples are given to illustrate the process of ~; the present invention. However~ it is to be understood that these examples ~5 are given merely for purposes of illustration and are not intended to limit the generally broad scope of the present invention in strict accordance therewith.
., `
-EXAMPLE_I
A series of expertmental runs to illustrate the operability of the process of the present invention was made using a lateritic nickel ore which had the follow~ng assay:
Nickel 1.75~
Cobalt0.072%
: Iron 25.7%
Magnesium 2.4~
Chromium l.O9X
Silica42.4%
The sample of the ore was ground to less than 65 mesh and utîlized by admixing 200 grams of a total charge of 1000 grams with 200 cc of a 15% hydrogen chlo-. ~ ride solution9 the mixture being allowed to interact for a period of 2 hours. The result;ng slurry was~then blended with 800 grams of additional dry ore and mixed with 20 grams of sulfur as pyrite. The resulting blend was then roasted in a fluid~bed reactor at a temperature oF 700 C. for 15 minutes under reducing conditions as provided for by a~producer gas type ... .
~; mixture containing carbon monoxide, hydrogen~, nitrogen, carbon dioxide and ` ~ water. After being treated in this manner the reduced ore was recovered ~:~ 20 and slurried with an ammoniacal ammonium carbonate solution. The slurry was agitated vigorously at amblent temperature for about 2.5 hours and there^
after filtered. The filtrate was then assayed for nickel content to deter-~: mlne the percent extractlon, said extraction amounting to 92.1%.
In contrast to this extraction procedure when the ore was reduced in a similar manner followed by extraction with an ammoniacal ammonium car-bonate solution without having been pretreated with hydrogen chloride and a sulfur-containing compound, it was found that only 28.7X of the nickel had bPen extracted.
.
~0~ 7 EXAMPLE II
In this example a lateritic nickel ore having the same composi-tion as that set forth in Example I above was treated in a normal manner by admixing the ore with aqueous hydrogen chloride and pyrite at an amount so that there was 4.6% hydrogen chloride and 2% sulfur present ln the mix-ture. The mix was then reductively roasted at a temperature of about 700 C.
at a rate of 7 pounds per hour in ar, externally heated tube reactor uti-lizing a rotating screw to convey the ore through the hot zone. The roast was effected in the presence of a producer gas type mixture containing ~; 10 carbon monoxide, carbon dioxide, hydrogen, nitrogen and water, the retention ; time of the hot zone being about 45 minutes.
The reduced ore was then slurried with an ammoniacal ammonium car-bonate solution and agitated at amblent temperature for a period of about
2.5 hours. Analysis of the filtrate disclosed that 83.4% of the nickel was extracted. This contrasted to a nickel recovery of only 28.7% when the ore was reductively roasted and extracted in the absence of any extraneous additives.
EXAMPLE I I I ~ : :
In this example a 10% solid slurry was used to scrub offgases from ; 20 the roasting of the ore in th~e run set forth in Example II above. The re-i . .
sulting slurry which recovered substantially all of the chloride regenerated in the roast was then mixed with an additlonal amount of fresh unreacted .. . .
ore and an additional amount of sulfur. The resulting mix was then reduc-tively roasted in a manner similar to that set forth in Example II aoove under similar conditions, that is, a charge rate of about 7 pounds per hour, reductive roast in a producer type gas mixture at 700 C. and a retention time of about 45 minutes. A~ter subjecting ehe reduced ore ~o an ammoniacal ammonium carbonate leach the filtrate was assayed and it was found that there had been an 86% extraction of the nickel.
.
EXAMPLE I I I ~ : :
In this example a 10% solid slurry was used to scrub offgases from ; 20 the roasting of the ore in th~e run set forth in Example II above. The re-i . .
sulting slurry which recovered substantially all of the chloride regenerated in the roast was then mixed with an additlonal amount of fresh unreacted .. . .
ore and an additional amount of sulfur. The resulting mix was then reduc-tively roasted in a manner similar to that set forth in Example II aoove under similar conditions, that is, a charge rate of about 7 pounds per hour, reductive roast in a producer type gas mixture at 700 C. and a retention time of about 45 minutes. A~ter subjecting ehe reduced ore ~o an ammoniacal ammonium carbonate leach the filtrate was assayed and it was found that there had been an 86% extraction of the nickel.
.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for the recovery of metal values from a metal bearing source wherein said metal bearing source is subjected to a roast in a reducing atmosphere at a temperature in the range of from about 550° to about 900°C. in contact with at least one additive selected from the group consisting of hydrogen halides, sulfur, sulfur-containing compounds and combinations thereof, cooling the metal bearing source, extract-ing the cooled metal bearing source, and recovering the desired metal value, the improvement which comprises pretreating a minor portion of said metal bearing source with said additive and thereafter admixing said treated minor portion of said metal bearing source with the remainder of said metal bearing source prior to the reduction thereof.
2. The process as set forth in claim 1 in which said metal value is nickel.
3. The process as set forth in claim 1 in which said additive is a hydrogen halide.
4. The process as set forth in claim 3 in which said hydrogen halide is hydrochloric acid.
5. The process as set forth in claim 1 in which said additive is sulfur or a sulfur-containing compound.
6. The process as set forth in claim 1 in which said additive is a combination of a hydrogen halide and sulfur or a sulfur-containing compound.
7. The process as set forth in claim 1 in which said minor portion of said metal bearing source is in a range of from about 1% to about 49% of the total feed.
8. The process as set forth in claim 1 in which the additive which is used to pretreat said metal bearing source is regenerated from the roast of said metal bearing source and recycled by contact with the minor portion of said metal bearing source.
9. The process as set forth in Claim 8 in which said minor portion of the metal bearing source and said additive are contacted in scrubber means prior to admixture with the remainder of said metal bear-ing source.
10. The process as set forth in Claim 6 in which one part of said minor portion of the metal bearing source is contacted in one scrubber means with one of said additives and thereafter admixed with the major portion of said metal bearing source and a second part of said minor por-tion of said metal bearing source is contacted with the other additive in a second scrubber means and thereafter admixed with the major portion of said metal bearing source.
11. The process as set forth in Claim 10 in which the contact of one part of the minor portion of said metal bearing source and the additive comprising sulfur or a sulfur-containing compound is effected in the presence of an added alkaline compound.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US67910576A | 1976-04-21 | 1976-04-21 | |
| US679,105 | 1976-04-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1094817A true CA1094817A (en) | 1981-02-03 |
Family
ID=24725572
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA276,278A Expired CA1094817A (en) | 1976-04-21 | 1977-04-15 | Hydrometallurgical recovery of metal values |
Country Status (7)
| Country | Link |
|---|---|
| AU (1) | AU507019B2 (en) |
| BR (1) | BR7702513A (en) |
| CA (1) | CA1094817A (en) |
| FR (1) | FR2348977A1 (en) |
| OA (1) | OA05653A (en) |
| PH (1) | PH13725A (en) |
| ZA (1) | ZA772358B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4187281A (en) * | 1978-08-07 | 1980-02-05 | Uop Inc. | Hydrometallurgical recovery of cobalt and nickel |
| FR2476681A1 (en) * | 1980-02-22 | 1981-08-28 | Uop Inc | Metal recovery by reductive roast and leaching - wherein roasting additive is recovered from off gas and recycled |
-
1977
- 1977-04-15 CA CA276,278A patent/CA1094817A/en not_active Expired
- 1977-04-19 ZA ZA00772358A patent/ZA772358B/en unknown
- 1977-04-20 BR BR7702513A patent/BR7702513A/en unknown
- 1977-04-21 AU AU24479/77A patent/AU507019B2/en not_active Expired
- 1977-04-21 FR FR7712041A patent/FR2348977A1/en active Granted
- 1977-04-21 PH PH19694A patent/PH13725A/en unknown
- 1977-05-06 OA OA56160A patent/OA05653A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR7702513A (en) | 1978-01-17 |
| AU2447977A (en) | 1978-10-26 |
| ZA772358B (en) | 1978-03-29 |
| PH13725A (en) | 1980-09-09 |
| OA05653A (en) | 1981-04-30 |
| AU507019B2 (en) | 1980-01-31 |
| FR2348977A1 (en) | 1977-11-18 |
| FR2348977B1 (en) | 1980-10-10 |
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