MXPA98000533A - Method for recovering nickel from lateritic mineral of ni-fe-mg rico in - Google Patents

Abstract

The present invention relates to a method for leaching in a leaching system a lateritic mineral containing Ni-Fe-Mg with high magnesium content in the particle state containing at least about 5% magnesium, at least about 10% of iron and at least about 0.5% nickel which is characterized in that it comprises: contacting the ore in particles of mesh size of less than about one inch (2.5cm) with a mineral acid solution selected from the group consisting of HC1, H2SO4 and HNO3, the concentration of the acid that is at least about 0.25 molar at a temperature at least ambient for a sufficient time to dissolve substantial amounts of nickel, including iron and magnesium and thereby form a nickel stock thereof, adjust the pH of the solution, if necessary, to a range of approximately 1 to 3, extract the nickel from the nickel stock solution by putting in with Touch the solution with a selective ion exchange resin for the absorption of nickel and therefore form a resin loaded with nickel and a refining containing acid, iron and magnesium, separate the refining from the resin, extract the nickel absorbed from the resin charged with nickel by contacting the resin with the mineral acid and forming a soluble nickel salt thereof as an eluate, and processing the nickel metal eluate

Description

METHOD FOR RECOVERING NICKEL FROM MINERAL LATERITICQ OF Ni-Fß-Mg RICQ IN Mg DESCRIPTION OF THE INVENTION This invention relates to the hydrometallurgical recovery of nickel from oxide minerals, in particular lateritic minerals rich in magnesium, such as saprolite. It is known that the minerals oxides or "ketoses," for example, those referred to as laterites, which include limonite and saprolite, are the largest potential sources in the world of nickel and cobalt. The ability to benefit these minerals by conventional techniques has placed these minerals at an economic disadvantage since these minerals can not be concentrated by magnetic separation or by flotation with foam compared to the sulfide minerals nickeliferous which can be easily concentrated to substantially lower levels. high nickel by well-known methods, such as foam flotation and matting. A process for recovering nickel and cobalt is the well-known Moa Bay process involving acid leaching at elevated temperatures and pressures in which iron oxide and aluminum oxysulfate are substantially insoluble. In the Moa Bay process, the laterite ore in the minus 20 mesh (95% passes the 325 standard mesh of the United States) is pulped to approximately 45% solids and the nickel and cobalt are selectively leaching with sufficient sulfuric acid at high temperature and pressure (eg 230 ° C to 250 ° C and 405 to 580 psia) to solubilize about 95% of each of nickel and cobalt in about 60 to 90 minutes. After the pressure decreases, the leached pulp is washed by decanting countercurrently with the washed pulp going to tails. The pH of the leached solution, which is very low (eg, between 0 and 0.5), is then neutralized with coral mud to a pH of about 2.4 in a series of four tanks in a total retention time of about 20. minutes and the product liquor of this treated form (containing approximately 5.65 gpl of Ni, 0.8 gpl of Fe and 2.3 gpl of Al), after solid-liquid separation, is then subjected to sulfide precipitation. The lixiviated liquor is preheated and precipitation of sulfides is carried out using H2S as the precipitating agent in an autoclave at approximately 120 ° C (250 ° F) and a pressure of approximately 150 psig. In the original scheme for treating mixed sulfides, the sulphide precipitate is washed and thickened at a solids content of 65%. This is then oxidized in an autoclave at about 177 ° C (350 ° F) and a pressure of about 700 psig.

The solution containing nickel and cobalt is then neutralized with ammonia at a pH (5.35) sufficient to precipitate any iron, aluminum and residual chromium present using air as an oxidizing agent. The precipitate is then separated from the solution and the nickel and cobalt solution is then adjusted to a pH of about 1.5. H2S is added to selectively precipitate any copper, lead and zinc present. The precipitate is separated from the solution by filtration and the nickel is recovered by several methods, a method comprising treating the solution containing the nickel with hydrogen at elevated temperature and pressure to produce nickel powder. The process mentioned above is similar to that described in "the prior art" indicated in U.S. Patent No. 4,097,575, the disclosure of which is incorporated herein by reference. Certain lateritic minerals, in particular saprolite minerals, generally have a high magnesium content and relatively low iron content compared to limonite which must be competitive in order to efficiently recover the nickel from the mother leach liquor and separate the nickel from the mother liquor. iron, magnesium and other impurities. The commercial practice is to melt high grade saprolitic minerals that generally contain in excess of about 2% nickel to produce either ferronickel or nickel matte. With respect to limonite, nickel is extracted from the ore by high pressure leaching using sulfuric acid as the leach and / or reduction roaster followed by leaching with ammonia. The acid leaching of the saprolitic mineral is not practiced commercially because the process has not been developed to recover the nickel from the leached solution in an economical and simple way. A typical magnesium-rich, iron-rich laterite generally contains by weight at least about 5% magnesium, for example, such as 10% and more. The Moa Bay process may not be adequate to treat such minerals due to excessive consumption of sulfuric acid due to the high magnesium content such as MgO in the ore. A method for leaching laterites of the saprolitic type under environmental temperature and pressure, eg, room temperature column / cell leaching and about 60 ° C to 80 ° C for leaching with stirring, wherein the by-products of oxides have been discovered herein. Magnesium and iron can be used as a good advantage to recirculate within the leach system as a means to control the pH of the mother nickel solution before nickel extraction from the solution. It is thus an object of the invention to extract nickel from lateritic minerals containing Ni-Fe-Mg containing relatively high amounts of magnesium and iron. Another object of the invention is to provide a method wherein the magnesium and iron oxides can be removed from the leach liquor before the recovery of the nickel from the stock solution. These and other objects will become clearer from the following description and appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS. Figure 1 is a flowchart for leaching the battery or bucket of magnesium-rich laterite ores (eg saprolite) using hydrochloric acid as the leaching solution; Figure 2 is a variation of the flow chart of Figure 1 where agitated leaching is used to extract nickel from the ore, the remainder of the process following leaching that is similar to the flow diagram in Figure 1; Figure 3 is illustrative of a modality in which a two-stage leaching method is employed using a countercurrent process in which the ore is leached in a second stage with the remaining leaching solids from the second stage recirculated to the first stage; Figure 4 is related to the use of sulfuric acid in the leaching of the tub or heap leaching of a magnesium-rich laterite mineral; Figure 5 represents a group of curves "comparing the leaching with agitation of saprolite to limonite; Figure 6 illustrates the relationship between acidity and addition of the mineral against time during neutralization in leaching with agitation; Figure 7 shows curves representing the extraction of nickel in the leaching of the tank under various conditions; Figure 8 are curves which represent the extraction of nickel in H2SO4 in the leaching of the tank under various conditions; Figure 9 is a flowchart for leaching the saprolite cell using hydrochloric acid; and Figure 10 is an illustrative scheme of various types of leaching. According to the present invention, the magnesium-rich laterite ores (e.g., saprolite), such as Ni-Fe-Mg containing ores containing at least about 5% Mg by weight, at least about 10% Fe , and at least about 0.5% Ni are subjected to dissolution by contacting the mineral with a mineral acid selected from the group consisting of HCl, H2SO4 and HN03 at a concentration of sufficient acid to effect the nickel dissolution, for example, at less about 0.25 molar. The leaching is carried out at a temperature of at least about the environment and is in the range of up to about 95 ° C for a sufficient time to dissolve substantial amounts of nickel and some iron and magnesium and provide a stock solution thereof. After leaching and removal of solids, the pH of the solution is adjusted, if necessary, to a range of about 1 to 3. The solution is then contacted with a selective ion exchange resin for the absorption of nickel the remaining refining containing Mg and Fe. A portion of the refining can be recirculated to the leaching stage, and the remaining portion subjected to pyro-hydrolysis to produce MgO and Fe203 The absorbed nickel is subsequently extracted from the ion exchange resin by in contact the resin with a mineral acid to form a solution of ní < quel as an eluate from which the ní < which is later recovered. As an eluent, the eluate can be repeatedly used after the acid adjustment to increase the nickel concentration for pyro-hydrolysis. In essence, the process of the invention involves leaching the cell, cell or shaking the mineral with a mineral acid, i.e., HCl, H2SO4 and HN03. After dissolution of the nickel, the leachate is adjusted in pH to approximately 1 to 3 using oxides of magnesium and iron produced in the process or the fresh mineral by itself. The nickel-containing leachate after separation of solids is subjected to an ion exchange treatment with a chelating resin, in particular, a Dow resin referred to as XFS-4195, in which the nickel is selectively charged leaving a poor solution of nickel (refined) or washing water which is recirculated in the leaching system. Where hydrochloric or nitric acid is used as the lixiviant, nickel chloride or nickel nitrate is formed and concentrated after the exchange of ions. The solution of nickel chloride or nitrate nitrate is subjected to pyro-hydrolysis to form nitric oxide and the recirculation acid, for example HCl, and HN03. Pyro-hydrolysis allows the recovery of magnesium oxide and iron oxide to be used as neutralizers to control the pH of the leachate at a level of about 1 to 3 to prepare the stock solution for nickel extraction by ion exchange. Pyro-hydrolysis also allows the recovery of MgO exclusively as a by-product or as a neutralizer to raise the pH of the raffinate to 6 or 7 to precipitate and separate iron and other impurities. After filtration, the MgCl2 solution is the stock solution for pyro-hydrolysis. The nickel oxide formed by pyro-hydrolysis can be used to produce metallic nickel or the nickel oxide in combination with iron oxide can be used to produce ferro-nickel. The flow chart for carrying out the process of the invention can include either one of Figures 1, 2, 3, 4 or 9, among other flow charts. The lateritic minerals are treated according to the amount of magnesium and iron as oxides present. These minerals are categorized as high magnesium and low iron content minerals (eg, saprolite) compared to low magnesium and high iron content minerals such as limonite. However, the iron content in some saprolite minerals may be relatively high (note Saprolite No. 3 in Table 1 below which contains 17.5% Fe by weight), although not as high as in the limonite minerals. In Table 1, three saprolite minerals are compared with limonite. Table 1: Elemental composition (%) of saprolite and limonite The difference in the behavior of leaching in the agitation tests between saprolitic minerals and limonite minerals will clearly appear from the curves of Figure 5 which shows that the leaching behavior of the two minerals is very different under the same conditions of leaching with stirring with HCl. As is clearly apparent from the table, the saprolite minerals have a relatively high magnesium content in the order of about 7.06%, 8.73% and 13.7% by weight. Limonite has a much lower magnesium content of about 2.84% by weight. With regard to Saprolite No. 1 or No. 2, the following conditions of leaching with hydrochloric acid are employed. Leaching with hydrochloric acid Saprolite mineral sample No. 1 and No. 2 Particle size 80% by weight through 200 mesh Concentration of 18% HCl at 6M Solids concentration 36% by weight at 600 gpl Leaching temperature Ambient temperature (23 ° C) and 60o- 80 ° C Leaching time Five hours As a result of leaching with agitation, an extraction of 67% at room temperature and 89% at a higher temperature range of about 60 ° C to 70 ° C is obtained. It is observed that the nickel leaching kinetics are moderately fast during the first 30 minutes and then relatively constant during the remaining leaching time. Impurities, such as magnesium, iron and manganese among others, exhibit similar kinetics, thus resulting in a substantially high consumption of acid in the initial leaching stage which indicates that nickel leaching is accompanied by decomposition of saprolite. In the leaching test mentioned here, the concentration of free HCl remaining in the leachate with agitation is 2M. Since high acidity will generally cause operational difficulties in the recovery by ion exchange of nickel, a suspension of pyro-hydrolysis magnesium oxide is added to the hot leachate (eg 70 ° C) to neutralize the residual free acid in the hot leachate. at a pH level of about 1. An advantage of the process of the invention is that the neutralizing agent, eg, MgO, is a byproduct of recirculation of the process. In this way, the treatment of the mineral rich in magnesium allows the use of a recirculation system in which the oxides comprising magnesium oxide and iron oxide are separated from the leachate as solids after the dissolution of the nickel and cobalt of the mineral, then used as a neutralizing agent to reduce the acidity of the final nickel solution to a pH range of about 1 to 3. As illustrative of the neutralization kinetics, reference is made to Table 2 below. Table 2: Composition of leachate at different acidity points Another method to neutralize the leachate is to use fresh saprolite mineral which contains both magnesium oxide and iron. The fresh saprolite mineral is added to a solution at a temperature of approximately 70 ° C. As in the use of recirculating magnesium oxide pej: = £, it is observed that the acidity decreases and the iron hydroxide precipitates almost completely when the acidity reaches 4-7 gpl. The fresh mineral is partially leached. The kinetics of the reaction tend to be slower as the acidity decreases. Neutralization of 600 ml of the leachate containing 81 gpl of HCl requires 849 grams of fresh saprolite ore. The results obtained are indicated in Table 3 as follows: Table 3: Neutralization of the leachate with fresh saprolite The total extraction for leaching and neutralization is in the vicinity of approximately 60.7%, although the recovery for this stage is approximately 29.8%. As will be indicated, the final sample contains 16.8 gpl of Ni. To eliminate the solid / liquid separation process, the leaching and neutralization step is carried out continuously without solid / liquid separation between the leaching and neutralizing steps. During neutralization, a suspension of fresh ore comprised of 600 gpl is fed at a constant rate of 10 ml / min. The results are shown in Table 4.

Table 4: Continuous leaching and neutralization results As will be indicated, the nickel concentration decreases after neutralization going from 10.2 gpl after leaching to 5.48 gpl after neutralization. This is due to the addition of water included in the suspension. Currently there is an increase in the amount of nickel leached after neutralization. A comparison of the acidity and mineral aggregate against time is shown in Figure 6. The nickel extraction for this process is 22.8%. A countercurrent leaching process appears to be attractive where the neutralization step is carried out using mineral fresh saprolita. In this process, the residue of the neutralization stage is leached under the same conditions as the initial leachate and the resulting leachate is then neutralized with fresh saprolite ore. The countercurrent process is illustrated in Figure 3. As an illustrative of the countercurrent process, the following example is given as it relates to Figure 2. Example 1 In the countercurrent leaching process, 300 g of the fresh mineral is leached at 80 ° C with 0.5 1 of 6 M hydrochloric acid and filtered to produce the leachate required for the neutralization stage. The fresh mineral is added to the leachate at 80 ° C and the acidity decreases to approximately 10 g / 1. The suspension is then filtered and the leachate is used in ion exchange. The residue is dried and added to 6 M hydrochloric acid at 80 ° C. The suspension is filtered and the residue sent to the queues. The leachate produced in this stage can then be heated and the fresh mineral added to it. After filtration, the liquid could go through the ion exchange and the cycle is repeated in this way. Column or pile leaching Five columns of approximately 60 inches (1.52 m) high and 4 inches (10.16 cm) in diameter are used in the process. The mineral 3 of saprolite (indicated in table 1) of particle size less than X inches (1.91 cm) is agglomerated with acid before it is loaded into the columns. The irrigation flow rate is 1.35 ml / min, which corresponds to 10 liters per square meter per hour. As indicated in the agitated leaching test, saprolitic "clay type" mineral exhibits poor permeability during filtration. In this way, the formation of mineral granules is an important resource to ensure uniform distribution of the reagent through the pile or column and to provide granules of sufficient conformation integrity to resist gravimetric flow and still ensure the desired permeability for irrigation or percolation of the reactive solution through the cell or column. A steady flow rate of 10 liters of the reagent solution per square meter per hour is used during the leaching of the ore, the granulation parameters used are as follows: Humidity (dry base) 20-60% Liquid acidity HCl 0-12 M Granule particle size Mesh +8 -1 inches Apparent density of the column 0.9-1.2 g / liter Porosity of the mineral column 25-40% The practical operating conditions are shown in Table 5. Table 5: Operating conditions of column leaching with HCl Figure 7 depicts the kinetics of nickel extraction under various conditions. The tests indicate that the leaching kinetics are proportional to the agglomeration acidity during the initial leaching period and subsequently become proportional to the acidity of the leaching solution. No significant influence is noted as for particle size in the leaching kinetics of the column or pile, at least in the particle size range of less than 34 inches used in the tests. The data in Table 6 compare the residual acidity of the leachate and Ni extraction., Mg, and Fe in both column leaching and leaching with agitation. The high acidity used in the agitation results in high iron extraction and high residual acidity in the leachate. As mentioned here above with respect to the neutralization of the magnesium oxide leachate or the mixture of magnesium oxide and iron oxide or fresh mineral, the lower acidity obtained after the neutralization causes iron precipitation within the column, which It is beneficial in minor iron extraction, except "that the high extraction of nickel also includes the extraction of magnesium. Table 6; Extraction of Ni, Fe and Mg and free acidity in the leaching with agitation with HCl and column leaching solutions.

* L2 and L4 are the key words of the test «that remain for the agitation. Leaching Tests No. 2 and No. 4 Consecutive column leaching In order to make full use of the high residual acidity in the column leaching and increase the degree of ní < When adjusting the pH of the leachate in the range of 1 to 1.5 for the next ion exchange, the leachates from columns 2 and 3 are brought to the specific feed acidity and fed to columns 4 and 5, respectively.

It is found «that extraction rates are not significantly affected by the presence of several ions in the feed solution. Two columns, NI and N2 are established to neutralize the leachate that is very acidic for effective ion exchange. NI is agglomerated with 1.4 M hydrochloric acid, N2 is agglomerated with water. When the leachates of columns 4 and 5 are fed to NI and N2, it is found that under these conditions, the nickel and magnesium are slowly leached but the iron is not extracted to a significant degree. The acidity of the resulting leachate remains in the range of 5-8 g / 1 of residual acidity even when the feed solution is changed from 9 g / l to 20 g / l of free acid. Leaching the column with sulfuric acid Three smaller sized columns are used, extending 4 feet (1.22 m) high and 5 inches (12.7 cm) in diameter. The saprolite sample No. 1 shown in Table 1 is agglomerated to the particle size of -3/4 inches mesh +10 and then loaded into each of the columns. Rapid leaching is carried out where the leaching flow rate increases from 10 to 100 liters per square meter per hour. The conditions under which the ore is formed into granules (or agglomerate) and leached with respect to the extraction of Ni, Fe and Mg are summarized in Table 7 and Table 8 below. Table 7: Operating conditions of column leaching with H2S04.

Table 8: Extraction of Ni, Fe and Mg in leaching with H2S04 A test is carried out using a larger column "which has a diameter of 6 inches (5.08 cm) and is 15 feet high (4.57 m). The column is loaded with 103 kg of particle saprolite less than 1 inch (2.54 cm). This is agglomerated with 25.6 liters of sulfuric acid 180 gpl. The acid concentration of the leaching solution is quantified at 30 gpl and controlled at a flow rate of 5 liters per square meter per hour. On day 66, the extraction of nickel, iron and magnesium is 21.71%, 2.26% and 18.05%, respectively. The figure 8 is illustrative of the kinetics of nickel extraction under various conditions for the three small columns and the large column.

Nickel recovery by ion exchange (TX) A chelating ion exchange resin referred to herein as Dow XFS-4195 is used to selectively recover nickel from the column leachates with hydrochloric acid and sulfuric acid. The active functional group is bis-picolylamine. Since the resin is an amine, the resin is protonated in an acid solution. The reference is made to Table 9 which lists the absorption constants for the different elements. The theoretical capacity for nickel is approximately 30 grams of nickel per liter of well-settled resin. Table 9: Absorption constants (K 1 / mol) of XFS-4195 (pH of sulphate solution = 2) Nickel recovery from the column leachate solution with HCl A column IX having a volume of 100 ml is used to treat four types of leachate solutions collected from column No. 2 to No. 5 leaching with HCl, respectively. The composition is given in Table 10 below. Table 10: The composition of the feed solution and chemical elimination solution.

The operating conditions are as follows: Bed volume (BV): 0.1 liter Flow rate: 0.05 BV / min. Load: 6 BV Washing No. 1: 1 BV Disposal solution ..: 1 BV Washing No. 2: 1 BV The elimination solution comprises 3 M HCl or about 109 gpl HCl. It is observed that the separation IX of the magnesium and nickel is completed and that the separation IX of the iron and nickel is influenced by the pH of the feed solution. A higher feed pH is favorable for separating nickel and iron. Table 11 compares the composition of the feed and disposal solutions for different pH of the feed solution. Table 11: The composition of the feed solutions and elimination of IX Nickel Recovery from the leaching solution of the column with H2S04. Two IX columns are used with a volume of 0.2 and 3 liters, respectively, to determine the recovery of nickel from the leaching solution with sulfuric acid at room temperature. The results obtained are shown in Tables 12 Y 13- Table 12: Composition of the feeding solution Table 13: Basic IX operational conditions The compositions of the feed and elimination solution obtained in each of the methods used are indicated in Table 14 which shows "that the slowest flow rate is favorable for the separation of the iron nickel. Table 14: The effect of the flow rates of the elimination solution on the Ni / Fe ratio Just as high concentrations of chlorides are favorable for pyro-hydrolysis, IX refining can be recirculated to the columns as a leaching solution after acidity adjustment and the IX elimination solution can also be recirculated as an elimination solution to increase the concentration of nickel before the pyro-hydrolysis of nickel. As will be clearly apparent, various flowcharts can be employed to carry out the novel inventive concept of the applicants. In this connection, the reference is made to the flow chart of Figure 1 which is directed to the heap leach or tub where the ore 1 is formed in a stack schematically shown at 2 in which HCl of concentration of about 3 molar to the stack from the top to the bottom and the solution is allowed to percolate down through the interstices of the ore, the ore having a particle size of less than about 3/4 inches. The leachate 3 containing the Ni, Fe and Mg chlorides is neutralized, if necessary, at a pH of about 1 to 2. The leachate is then passed through an ion exchange bed of Dow XFD 4195 resin. Nickel is selectively absorbed by the resin (4) from which a refined "containing Mg and Fe is obtained, part of which (5) is recirculated to the heap leaching by means of which the Mg and Fe concentration in the raffinate is increased. Part of the raffinate (6) containing high amounts of Mg and Fe is subjected to pyro-hydrolysis (7) to produce MgO and Fe203 (8) and HCl (9) which is recirculated to the bed of the resin (4) to extract nickel as nickel chloride (10) and to the heap leach (2) via line 9. The obtained elimination solution is recirculated after adjusting the acidity with HCl in such a way that the Nickel grade is increased. The nickel chloride (10) extracted from the resin can be subjected to pyro-hydrolysis (11) to form nickel oxide or, depending on the concentration of the nickel in the solution, the solution of nickel chloride can be sent to electrolysis to produce electrolytic nickel. In Figure 9, the flow diagram of Figure 1 is modified to separate iron from magnesium by neutralization and recirculate the acidic water generated in the process. Therefore, the accumulation of chloride in the leaching system, which decreases the nickel loading capacity of the resin, is under control. The ore is leached in the same way using the combined streams of hydrochloric acid produced through the pyro-hydrolysis (60 and 65) and the acid wash water (49 and 51) produced in the ion exchange wash step (51). ) and the acid water used to wash the pile (49) when the leaching ends. The refining solution high in iron and magnesium concentration (53) is neutralized to pH 6-7 and the waste solid Fe (OH) 3 is separated by filtration. The remaining liquid (57) composed of the MgCl2 solution is hydrolyzed by pyrolysis (59) to produce MgO (61), condensed water (62) and HCl (60) which are all recirculated to the process. MgO can be a desired product. Part of the eluting NiCl2 solution is used in the resin removal process after the acidity is increased. The other part of the NiCl2 solution is hydrolyzed by pyrolysis to produce NiO. The flow chart of Figure 2 is similar to that of Figure 1 except for the use of agitated leaching to treat the ore. After leaching with stirring the mineral (1) with HCl in step (2) at a concentration of approximately 6 molar and a temperature of approximately 80 ° C, a solution (3) containing Ni, Fe and Mg is produced. After the separation of the gangue material, this solution is passed over the neutralization step (4A). The solution is then neutralized to a pH of about 1 to 2 using recirculating Mgo or the mixture of MgO or fresh mineral which is described hereinafter. The nickel-containing solution is passed to the resin bed (4B) comprised of a selective nickel absorption resin, for example, DOW XFS 4195 of the type referred to as Bis (2-picolyl) amine or N- (2-hydroxyethyl). 2-picolylamine Another nickel-absorbing resin that can be used is one in which the resin is a macroporous polystyrene copolymer with a basic linked chelating picolylamine derivative, i.e., specifically N- (2-hydroxypropyl) -2-picolylamine Nickel is extracted from the resin with HCl, generally recirculated HCl, as NiCl2 (10). Nickel chloride can be subjected to pyro-hydrolysis (10A) to form NiO (10B) which can then be reduced to metallic nickel. , such as reduction by hydrogen 10C to form nickel powder (10D) On the other hand, depending on the concentration of the nickel chloride, the nickel can be recovered by electrolysis.After the absorption of nickel with resin (4B), the solution The remaining one containing high amounts of Fe and Mg is subjected to pyro-hydrolysis which results in the formation of recirculated HCl (8) and (MgO + Fe203) (9) which is recirculated to the neutralization stage (4A). The HCl is recirculated to either or both of the bed of the resin (4B) and / or leaching 2 with agitation, thus maintaining HCl within the system for recirculation, except for the addition of concentrated HCl, if necessary. Another embodiment of a flow diagram for carrying out the objects of the invention is shown in Figure 3. In this case, the two-stage leaching is employed where the solids (18) remaining from the leaching of the ore in the second stage are used. Leaching stage are recirculated to the first stage. The mineral (15) (high magnesium saprolite) is fed the leaching from the second stage (16) where it is leached using the liquid from the first leaching stage (20) to decrease the residual acidity. The leaching of the first stage is carried out on the solids (18) recycled from the second leaching stage (16). An 18% solution of HCl (19) is added to the solids (18) the reaction product of which is fed to the solid / liquid separation (20A) where the residue (21) is removed leaving a liquid (17) which is passed to the second leaching stage (16) to form solids / liquids (16A), with the solids thereof recirculated to the first leaching stage for additional leaching. The solution (16B) is passed to the neutralization step (22) in which recirculating MgO (23) is added to form solids / liquid (25) from which the Fe203 solids are removed. The liquid containing nickel chloride is subsequently treated with recirculated MgO in step (26) to precipitate Ni (OH) 2 (27) and form MgCl2 (28), the MgCl2 solution which is subsequently subjected to pyro-hydrolysis (29). ) to form MgO (23) to recirculate the system as a neutralizing agent and HCl (30) to recirculate to the first leach stage (20). Figure 4 illustrates column or heap leaching of a lateritic ore with high magnesium content (eg, saprolite) using H2SO4 as the leach. The agglomerated mineral (31) with a particle size of less than one inch (2.54 cm) is added to the column (32) or formed in a self-supporting stack through which sulfuric acid (33) of a concentration of 0.1 to 2 M, the acid that percolates through the interstices of the granulated mineral from the top to the bottom. The leachate leaving the bottom of the column or stack is then subjected to neutralization (34) using fresh mineral (31) as the neutralizing agent., as shown in the consecutive column or in the agitation tank. The neutralized free solids leachate is then passed through a bed of a selective ion exchange resin (36) for the absorption of nickel, such as Dow XFS-4195. After absorption of nickel, the H 2 SO 4 (35) concentration of about 1 to 2 M is passed through the bed of the resin to extract the nickel as nickel sulfate (37) with liberated sulfuric acid including magnesium and iron during the absorption of nickel recirculated partially to the leaching stage of column 32 and step 42 of neutralization with lime (41).

After neutralization with lime, Fe203 (44) is precipitated and a solution of MgSO4 (45) is produced. The MgSO4 solution can also be processed to produce Mgo and sulfuric acid to recirculate in the system. When preparing the ore for leaching, the ore as obtained from the mine is crushed using a jaw crusher with the jaws fixed in a space of approximately 1 inch to 3 inches. The ore is passed once through the jaw crusher. A typical particle size of the crushed ore is shown in Table 15 as follows: Table 15: Particle size distribution (% by weight) of saprolite ore measured with dry sieve To produce the granulated mineral, a rotary granulator well known in the art can be employed. In the tests carried out, the granules are manually agglomerated causing a mixture of the mineral and liquid to move in a particular trajectory and form ball-like conformations. In the case where coarse particles are present, the coarse particles are generally coated with fine particles to form agglomerated granules together with granules formed of fine particles. A typical size distribution of agglomerated granules for use in heap column leaching is shown in Table 16 below: Table 16: Particle size distribution (% by weight) of the agglomerated granules.

With reference to Figure 10, various types of leaching procedures are illustrated. Section (A) is illustrative of in situ leaching of a mineral body, referred to as submarginal mineral, with an operational capacity of 4x10d ton. of ore for the time sequence shown. Section (B) shows the "deposit leaching" where the ore pile is obtained by demolition. The operational capacity is approximately 5x106 tons of ore for the period shown. Heap leaching is shown in the section (C) which has an operational capacity of 3x105 tons of the mineral for the period indicated. The leaching of the tank is illustrated in the section (D) This type of leaching is similar to the heap leaching with an operational capacity of 5x103 tons of ore for the period shown. Section (E) illustrates the leaching of mineral water due to water collected after rain in open pit mines. All the above methods are referred to static procedures. Section (F) of the drawing shows a more dynamic process for bioleaching, wherein the ore is finely ground and treated by bacteria together with for example, a solution of iron sulphate, in a stirred reactor. In essence, the modalities illustrated in Figures 1-4 have a central theme, namely, the recovery of nickel from lateritic ore with high magnesium content (eg, saprolite) without the need to melt the oxide mineral to produce ferronickel or nickel matte that has long been the practice. In summary, the novelty or key aspects of the present invention reside in the following: (1) Extraction of nickel from saprolitic ore with high magnesium content under atmospheric pressure and temperature. (2) Agglomeration of saprolitic clay-like mineral in granules in order to obtain a uniform distribution of the leaching solution through the pile or column of ore, including sufficient granule conformation integrity to inhibit the gravimetric flow thereof; (3) The extraction of nickel under atmospheric pressure and temperature of about 60 ° C to 80 ° C with leaching with agitation, or leaching from cell or cell; (4) The separation of the nickel from Fe and Mg by means of ion exchange treatment of the stock solution while in contact with a specific resin for the extraction of nickel in the preference to Fe and Mg at a pH of about 1. to 3; (5) Adjust the pH of the leaching solution during leaching of the consecutive stack using fresh ore or recirculated iron and magnesium oxides produced from the pyro-hydrolysis stages; and (6) The use of recirculation such as: (a) The recirculation of regenerated acid to the leaching system; (b) The recirculation of the refining solution in the leaching system as shown in Fig. 1; (c) The recirculation of the wash solution in the leaching system as shown in Fig. 9; and (d) The recirculation of MgO and Fe0H3 formed during leaching to the leaching system to adjust the pH. Using the hydrometallurgical process described herein, substantially pure nickel of mineral with high magnesium content is recovered. Although the present invention has been described in conjunction with preferred embodiments, it is understood that modifications and variations may occur without departing from the spirit and scope of the invention as those skilled in the art will readily understand. Such modifications and variations are considered to be within the scope and scope of the invention and appended claims.

Claims (1)

1. CLAIMS 1. A method for leaching in a leaching system a lateritic mineral containing Ni-Fe-Mg with high magnesium content in the particulate state containing at least about 5% magnesium, at least about 10 & of iron and at least about 0.5% of nickel which is characterized in that it comprises: Contacting the ore in particles of mesh size of less than about one inch (1 cm) with a mineral acid solution selected from the group consisting of HCl , H2S04 and HN03. The concentration of the acid "which is at least about 0.25 molar at a temperature at least ambient for a sufficient time to dissolve substantial amounts of the nickel, including iron and magnesium, and thereby form a nickel stock thereof, Adjust the pH of the solution, if necessary, to a range of approximately 1 to 3. Extract the nickel from the nickel stock solution by contacting the solution with a selective ion exchange resin for the absorption of nickel and therefore form a resin loaded with nickel and a refining that contains the acid, iron and magnesium, Separate the refining of the resin, Extract the nickel absorbed from the resin charged with nickel by contacting the resin with the mineral acid and form a soluble nickel salt of the same as an eluate, and process the metallic nickel eluate 2. The method according to claim 1, characterized in that the pH of the leachate is a Just adding a neutralizing agent to the leachate, any residue that remains in the leached pH is removed before nickel extraction from the leachate. 3. The method according to claim 1, characterized in that the mineral acid to leach the mineral is HCl; The nickel absorbed from the nickel-laden resin is extracted with an HCl solution to form a nickel chloride solution; The nickel chloride solution is subjected to pyrohydrolysis to form NiO; and NiO is also processed to metallic nickel. 4. The method according to claim 2, wherein the laterite ore with high content of particulate magnesium is prepared for leaching the pile forming a mass of the ore having an upper part and a lower part and characterized by interstitial voids through it, 5 Where the mass of the ore is leached by the gravimetric flow of a stream of mineral acid from the top of the mass to its bottom; The flow velocity of the acid solution that is 10 sufficient in such a way that substantial amounts of nickel are leached from the ore mass to form a nickel mother solution thereof and a residue; Where the stock solution is separated from the residue 15 for additional treatment; Where the stock solution is contacted with the selective ion exchange resin for the absorption of ní < quel to provide a refined "containing iron and magnesium; Wherein the nickel is separated from the resin by the mineral acid to form a soluble nickel salt as an eluate thereof; and wherein the substantially pure nickel is recovered from the eluate. 5. The method according to claim 4, characterized in that the mineral acid for leaching the ore pile is HCl; Where the nickel absorbed from the nickel-loaded resin is removed with an HCl solution to form a nickel chloride solution; Where the nickel chloride solution is subjected to pyrohydrolysis to form NiO; and Where the NiO is also processed to metallic nickel. 6. The method according to claim 4, wherein the laterite mineral with high magnesium content in particles of particle size less than about 1 inch (1 cm) is formed into granules by agglomerating the particulate mineral. with hydrochloric acid of concentration in the range of up to about 12 M and therefore form granules of average size of less than about one inch (1 cm) characterized by sufficient conformation integrity to form a self-supporting mass in the form of a or inside a column with interstices distributed completely in the mass to allow the irrigation and / or percolation of the mother solution through it and therefore produce a solution of mother nickel. 7. The method according to claim 1, characterized in that a suspension of lateritic ore with high magnesium content is formed with a hydrochloric acid leaching solution of at least about 0.25 molar; Where the leaching solution extracts Ni, Fe and Mg from the ore and leaves a residue; Where the residue is separated from the leaching solution; Wherein the leaching solution is passed through a bed of a selective ion exchange resin for the absorption of nickel and produces a nickel-deficient refining and containing Fe and Mg; Wherein the absorbed nickel is extracted from the resin with HCl to provide an eluate of the nickel chloride; Wherein the eluate is subjected to pyrohydrolysis to form NiO; and wherein the nickel-deficient raffinate is subjected to pyrohydrolysis to form MgO / FeOH3 to recirculate to the leach system as a neutralizing agent and produce HCl to recirculate to the leach system and to recirculate the ion exchange resin as an elimination agent . 8. The method according to claim 1, wherein the high-magnesium lateritic mineral is subjected to bowl leaching characterized in that it comprises; Form a charge of the particulate mineral in a vat «that has an inlet end and an end 10 departure; Pass the mineral acid through the tank at a sufficient flow rate to extract substantial amounts of the nickel from the ore as a stock solution that includes iron 15 and magnesium; Contacting a solution of mother liquor with a resin selective to the absorption of nitrogen and forming a resin loaded with nickel and a refined nickel-deficient and containing Fe and Mg; 20 Pass mineral acid through the bed of the nickel-laden resin to extract nickel as a soluble salt of the mineral acid as an eluate therefrom; and then recover the nickel from the eluate. 9. The method according to claim 8, characterized in that the resin is a bis (2-picolyl) amine resin. 10. The method according to claim 8, characterized in that the mineral acid is H2SO4; Wherein the eluate containing nickel is nickel sulfate solution; Where the nickel sulfate solution is subjected to electroextraction to form substantially pure electrone nickel. 11. A method for recovering nickel from lateritic ore with high content of magnesium in particles containing Ni, Fe and Mg by countercurrent leaching characterized in that it comprises: Providing a first stage of leaching and a second stage of leaching wherein the first leaching and the neutralization is carried out in the second stage of leaching; Leach the mineral with a mineral acid in the second stage of leaching to form a solution containing ferroniquel, magnesium and recyclable solids; Submit the leached ore to solid / liquid separation and for the same recover the recyclable solids for additional leaching in the first stage of leaching; Recirculate the solids to the first stage of leaching to which the recirculated mineral acid is added; 5 Pass a first leach from the first stage of leaching to the second stage of leaching to which fresh mineral is added for primary leaching; Leach the mineral in the second stage; 10 Pass the second leached mineral to the solid / liquid separation to separate solids from the leachate formed during leaching; Recirculate the solids from the second stage of leaching to the first leaching together with 15 recirculated mineral acid; Submit the leachate to additional neutralization with recirculated Mgo; Neutralization «which is enough to precipitate a basic iron compound in a solution that 20 contains dissolved nickel and magnesium; Substitute the solution containing Ni / Mg to solid / liquid separation to remove the precipitate and provide a solution containing Ni / Mg; Adjust the pH of the solution with recirculated MgO 25 to selectively precipitate Ni (0H) 2 and provide a solution containing dissolved magnesium; Hydrolyze the magnesium-containing solution by pyrolysis to form a MgO precipitate; and Recirculate the MgO precipitate to the leachate resulting from the first and second leaching stages to neutralize the leachate at a desired pH to precipitate the basic iron compound and provide a solution containing the Ni and the Mg from which Mg is separated as a solution for hydrolysis by pyrolysis. 12. The method according to claim 11, characterized in that the mineral acid is HCl. 13. A method for leaching the lateritic ore pile containing Ni-Fe-Mg magnesium in the particulate state containing at least about 5% Mg, at least about 10% Fe and at least about 0.5% nickel in weight which includes: Agglomerate the mineral into particles of particle size of less than about one inch (1 cm) with hydrochloric acid of the concentration in the range of up to 10 M. Form a pile of the agglomerated mineral, The ore pile which is characterized by interstices through the pile to pass hydrochloric acid through them, allowing the hydrochloric acid of concentration of at least about 0.25M to percolate through the pile of the mineral at a rate sufficient to effect the dissolution of the nickel as nickel chloride together with some iron and magnesium as chlorides and form a mother solution thereof; Pass the stock solution through the bed of the selective resin for the absorption of nickel in Preference is given to iron and magnesium chlorides in which chlorides are removed as a raffinate. Subject the refining to neutralization at a selective pH for iron precipitation as FeOH3 while maintaining magnesium chloride 15 in solution; Pass an HCl removal solution of approximately 2 to 6 molar through the bed of the resin after washing the resin with wash water to extract the nickel from it as 20 nickel chloride; Submit the magnesium chloride solution to pyrohydrolysis to form MgO suitable for recirculation to neutralization; Hydrolyze the nickel chloride solution in a 25 separate pyrohydrolysis step to produce NiO and HCl to recirculate to the heap leach and produce water to recirculate as wash water within the leach system, and recover NiO nickel. 14. A method for leaching into a leach system comprising a first leach stage and a second leach stage, a lateritic Ni-Fe-Mg mineral containing high amounts of magnesium containing at least about 0.5% Ni, at least about 5% magnesium and at least about 10% iron, which is characterized in that it comprises: Feeding a charge of the mineral in mesh size particles of less than about an inch to the second stage of leaching, Add to the charges hydrochloric acid of concentration of at least about 0.25 molar to a temperature of at least sufficient to dissolve substantial amounts of nickel from the ore and form a solution of mother nickel chloride containing iron chloride, magnesium chloride and undissolved solids, recirculate the solids not dissolved in the first stage of leaching, Submit the solution of nickel chloride mother to neutral enough to precipitate iron hydroxide and provide a solution of nickel chloride and magnesium chloride, Separate the iron hydroxide from the mother nickel chloride solution, Neutralize the mother nickel solution enough to form nickel hydroxide and leave a solution of magnesium chloride, Substitute the magnesium chloride solution for pyrohydrolysis to form recirculated hydrochloric acid and recirculated MgO for neutralization, And recirculate the hydrochloric acid to the first stage of leaching to leach the recirculated solids of the second leaching stage. 15. The method according to claim 14, characterized in that the MgO formed by pyrohydrolysis is recirculated to the first leaching stage. The method according to claim 14, characterized in that the hydrochloric acid formed by pyrohydrolysis is recirculated to the first leaching stage. 17. The method according to claim 14, characterized in that the nickel hydroxide is converted to metallic nickel by thermal reduction. The method according to claim 14, characterized in that the nickel hydroxide is dissolved in sulfuric acid to form a solution of nickel sulfate containing acid, and wherein the nickel sulphate solution is subjected to electrolysis to form nickel substantially pure