OA20003A - Alkaline oxidation methods and systems for recovery of metals from ores. - Google Patents

Abstract

An oxidation step for sulfide and transition ores prior to CN leaching to recover 60 to 90 percent of metals from those ores. Use of tona, soda ash or carbonate source in treating sulfide and transition ores for CN leaching recovery of metals, including gold and silver. The oxidation of sulfide and transition ores in the presence of carbonate. Low moisture content in the heap, to enhance available oxygen, during the oxidation of sulfide and transition ores in the presence of carbonate. <img file="OA20003A_A0001.tif"/>

Description

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] The présent inventions relate to mining and ore recovery methods and Systems, including leach pad methods and Systems for recovery of metals from ores containing sulfur.

[0003] Leaching of sulfide and transition ores has many challenges and prior to the présent inventions was not economically possible or feasible for low-grade ore bodies. These problems include that pH must be maintained at optimal ranges. pH has a profound impact on Au-CN complex stability. The most commons pH modifiers in gold extraction are calcium hydroxide (lime) or sodium hydroxide (caustic soda) and testing has shown that with most gold ore the best gold libération is at pH 9.9-10.4. If lime is used and the pH is too high Ca-precipitates, Fe-OH is formed and gold cyanide formation is disrupted due to decreased free cyanide concentrations. These problems resuit in the kinetics slowing and eventually leading to the failure of the leach heap to economically recover gold.

[0004] The iinability to process sulfide ore and transition ore in leaching heaps has been a long standing problem. Sulfides, when présent in a heap leach Opérations, will oxidize and produce acid. More lime will be required to neutralize this acid, than a traditional oxide heap. In some cases, caustic soda is added as a short term préventive !

method, but can form gelatinous précipitâtes with silica, which plug leach drip emitters i i and irrigation lines and flow paths in the heap. Lime is also known to passivate pyrite surfaces precluding or limiting oxidation needed to facilitate gold and silver recovery. Thus, preventing a runaway process resulting in the ultimate failure of the heap.

[0005] Predicting how much more lime is required at any one point in time in a sulfide and transition ore heap leach is almost impossible and does not provide a solution to this long standing problem. Lime requirements and needed addition, cannot be adequately predicted because obtaining a représentative sample is extremely difficult due to the dynamics of the heap. If lime addition is underestimated, acid production will outrun the initial neutralizing power of the heap. The current heap leach pH monitoring and control technology is not equipped to handle such an event, and once the entire heap is net acidic gold recovery drops to zéro and the opportunity to reestablish leaching it is essentially lost. This is a signifîcant and very costly risk and problem, that prior to the présent inventions the art has been unable to solve.

[0006] A further problem with sulfide and transition ore heap leaching is that increasing alkalinity to neutralize a runaway heap is limited by the irrigation rate, preferential flow paths in the heap and the solubility of lime in water. There are physical limitations with this approach that cannot be improved. Short term addition of caustic soda may spike the pH but does not provide the essential alkalinity needed for longer term acid buffering and has precipitate problème which impacts the operation.

[0007] Ultimately, prior to the présent inventions ail sulfide and transition ore heap leach Systems using lime will fail at some level. With these failures there is lost revenue, and more significantly and detrimentally sterilization of recoverable Au, Ag.

[0008] As used herein, unless specified otherwise, “mining”, “mine” and similar such terms, are used in their broadest possible sense; and would include ail activities, locations and areas where materials of value, e.g., ore, precious metals, minerais, etc., are removed or obtained from the earth.

[0009] As used herein, unless specified otherwise, “leaching”, “heap leaching”, “heap” and similar suJh terms, are used in their broadest possible sense; ^ind would include ail activities, locations and Systems where processes, including industrial mining processes extract precious metals, such as gold, silver, copper, aluminum, uranium and other éléments and compounds from ores through a sériés of Chemical reactions.

[0010] As used herein, unless specified otherwise these terms are used as follows. Ores having cyanide-soluble métal, e.g., gold, contents of 70% or higher are classified as “oxide ore.” Those with cyanide-soluble métal, e.g., gold contents below 30% are considered “sulfide.” The remainder, with cyanide-soluble métal, e.g., gold contents between 30 to 70% are considered “transition ores.”

[0011] The sulfide sulfur concentration in sulfide ores can range from 0.5% to 5 as high as 10%, be from about 0.1% to about 5%, about 0.5% to about 2%, about 1% to 10% and higher and lower concentrations. The sulfide sulfur concentration in transition ores can be from can range from about 0.5% to as high as 10%, 0.1% to about 5%, about 0.5% to about 2%, about 1 % to 10% and higher and lower concentrations. Pyrite ore typically has a cyanide-soluble gold content of less than 30%, less than 20% and 10 less than 10%; and has a sulfide sulfur concentration of 0.5% to as high as 10%, about 0.1% to about 1%, about 0.5% to about 2%, and about 1% to about 10%, and higher and lower concentrations.

[0012] As used herein, unless specified otherwise the terms %, weight % and mass % are used interchangeably and refer to the weight of a first component as a 15 percentage of the weight of the total.

[0013] As used herein, unless specified otherwise “volume %” and “% volume” and similar such terms refer to the volume of a first component as a percentage of the volume of the total, e.g., formulation, mixture, preform, material, structure or product.

[0014] Generally, the term “about” and the symbol as used herein, unless specified otherwise, is meant to encompass a variance or range of ±10%, the experimental or instrument error associated with obtaining the stated value, and preferably the larger of these.

[0015] As used herein unless specified otherwise, the recitation of ranges of

I 25 values herein is merely intended to serv4 as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value within a range is incorporated into the spécification as if it were individually recited herein.

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[0016] As used herein, unless stated otherwise, room température is 25°C.

And, standard ambient température and pressure is 25°C and 1 atmosphère. Unless expressly stated otherwise ail tests, test results, physical properties, and values that are température dépendent, pressure dépendent, or both, are provided at standard ambient température and pressure, this would include viscosities.

[0017] This Background of the Invention section is intended to introduce various aspects of the art, which may be associated with embodiments of the présent inventions. Thus, the forgoing discussion in this section provides a framework for better understanding the présent inventions, and is not to be viewed as an admission of prior art.

SUMMARY

[0018] The présent inventions advance the art and solve the long standing need for efficiently removing minerais and precious metals from ores. In particular, the présent inventions solve the long standing problem of recovering precious metals and minerais, e.g., gold and silver, from sulfide containing ores using heap leach operations. The présent inventions, among other things, advance the art and solves these problems and needs by providing the articles of manufacture, devices and processes taught, and disclosed herein.

[0019] There is provided a System for the processing and recovery of metals from ores having high sulfide content, the System having: a crushing segment having: (i) an ore having a métal and a sulfide; and, (ii) crushing equipment; an oxidizing pH moderating material handling and distribution segment, the handling and distribution segment having an oxidizing pH moderating material and distributing equipment; wherein handling and distribution segment is configured to meter and add the oxidizing pH moderating material to the ore having a métal and a sulfide; the crushing segment, the handling and distribution segment, or both, configured to mix and conduct an oxidation reaction; and, whereby the sulfide is ox^dized and thereby creating a preoxidized ore; a heap leach segment, having the pre-oxidized ore and a reagent for extracting the métal from the pre-oxidized ore, thereby forming a solution having the métal; a métal recovery segment, whereby the métal is recovered from the solution.

[0020] Still further, there is provided these Systems and methods having one or more of the following features: wherein the System is a surface mine in the earth; wherein the ore includes a sulfide ore; wherein the ore includes a transition ore; wherein the ore includes a sulfide ore and a transition ore; wherein the ore includes a sulfide ore, a transition ore and an oxide ore; wherein the ore includes a sulfide ore and an oxide ore; wherein the ore includes a transition or and an oxide ore; having a holding pile of pre-oxidize ore, wherein the oxidation reaction continues in the holding pile; wherein the ore has a moisture content of from about 2% to about 10%; wherein the ore has a moisture content of from about 2% to about 5%; wherein the pre-oxidized ore in holding pile has a moisture content of from about 2% to about 10%; wherein the preoxidized ore holding pile has a moisture content of from about 2% to about 5%; wherein the ore has a density is about 40%; wherein the ore has a density of about 20% to about 60%, and ail values within this range; wherein the pre-oxidized ore in holding pile has a density of about 30% to about 50%; wherein the métal recovery segment is a Merrill-Crowe plant; wherein the métal recovery segment includes a zinc cementation System; wherein the oxidizing pH moderating material includes trôna; wherein the oxidizing pH moderating material includes soda ash; wherein the pre-oxidized ore has a P80 particle size of from about 0.25 inches to about 1 inch; and wherein the preoxidized ore has a P80 particle size of from about 0. 5 inches to about 0.75 inches.

[0021] Additionally, there is provided a System for the processing and recovery of metals from ores having high sulfide content, the System having: a crushing segment having; an oxidizing pH moderating material handling and distribution segment, the handling and distribution segment having an oxidizing pH moderating material and distributing equipment; wherein handling and distribution segment is configured to meter and add the oxidizing pH moderating material to an ore having a métal and a sulfide; the oxidizing pH moderating material selected from the group consisting of trôna, soda ash, and a mixture of soda ash and trôna; the crushing segment, the handling and distribution segment, or both, configured to mix and conduct an oxidation reaction; a heap leach segment, having a pr^-oxidized ore having a particle size of from about 0.5 inches to about 0.75 inches, and a reagent having cyanide, for extracting the métal from the pre-oxidized ore; and, a métal recovery segment.

[0022] Furthermore, there is provided these Systems and methods having one ! i or more of the following features: having a sulfide ore, the sulfide ore having a métal enrichment and wherein the métal recovery segment includes at least about 60% of the métal from the métal complex in the ore; having a sulfide ore, the sulfide ore having a métal enrichment, and wherein the métal recovery segment includes at least about 70% of the métal from the métal complex in the ore; having a sulfide ore, the sulfide ore having a métal enrichment, and wherein the métal recovery segment includes at least about 80% of the métal from the métal complex in the ore; and wherein the métal is 5 selected from the group consisting of gold, silver and cooper.

[0023] In addition there is provided a system for the Processing and recovery of metals from ores having high sulfide content, the system having: a crushing segment having: (i) an ore having a métal and a sulfide; and, (ii) crushing equipment; an oxidizing pH moderating material handling and distribution segment, the handling and distribution 10 segment having an oxidizing pH moderating material and distributing equipment;

wherein handling and distribution segment is configured to meter and add the oxidizing pH moderating material to the ore having a métal and a sulfide; the crushing segment, the handling and distribution segment, or both, configured to mix and conduct an oxidation reaction; whereby the sulfide is oxidized and thereby creating a buffered pre15 oxidized ore; a heap leach segment, having the pre-oxidized ore and a reagent for extracting the métal from the pre-oxidized ore, thereby forming a solution having the métal; and, a métal recovery segment, whereby the métal is recovered from the solution.

[0024] Yet further, there is provided these Systems and methods having one 20 or more of the following features: having a holding pile of pre-oxidize ore, wherein the oxidation reaction continues in the holding pile; wherein the buffered pre-oxidized ore has a pH of about 8 to about 10; wherein the buffered pre-oxidized ore is buffered to a pH of 10.3; wherein the buffered pre-oxidized ore is buffered to a pH of about 10.3; wherein the pre-oxidized ore has a total alkalinity of about 15,000 ppm to about 60,000 25 ppm; wherein! the pre-oxidized ore has a total alkalinity of 15,000 ^pm to 60,000 ppm; wherein the pre-oxidized ore has total alkalinity of about 20,0000 ppm; and wherein the pre-oxidized ore has total alkalinity of 20,0000 ppm.

I I

[0025] In addition there is provide a system for the processing and recovery of i I metals from sulfide ores, the system having: a means for crushing, the means having: 30 (i) an ore having a métal and a sulfide; and, (ii) a primary and secondary crusher; a means for delivering an oxidizing pH moderating material to the ore, the means having an oxidizing pH moderating material selected from the group consisting of trôna, soda ash, and sodium nitrate; a means for mixing the oxidizing pH moderating material and ore; and, a means for conducting an oxidation réaction; whereby the sulfide is oxidized and thereby creating a pre-oxidized ore; and a means for separating and recovering the métal from the pre-oxidized ore; whereby at 70% of the métal is recovered from the ore.

[0026] A method for the processing and recovery of metals from ores having high sulfide content, the method having: a means for crushing, an ore having a water content and a métal and a sulfide; mixing the oire with an oxidizing pH moderating material, and thereby forming a mixture of the ore and the oxidizing pH moderating material; the oxidizing pH moderating material: oxidizing the sulfide for a first time period; buffering the mixture; whereby the mixture has a pH of about 7 to about 10 during the first time period; whereby a pre-oxidation ore is formed during the first period of time, the pre-oxidized ore having a percentage of the sulfide oxidized; during a second time period leaching the pre-oxidized ore with a reagent to form a prégnant solution having the métal; recovering the métal from the prégnant solution, whereby 60% to 95% of the métal is recovered from the ore.

[0027] Moreover, there is provided these Systems and methods having one or more of the following features: having rinsing the pre-oxidized ore after the first period of time; having rinsing the per-oxidized ore before the second period of time; having second time period and the first time period do not overlap; wherein the first time period is from about 30 days to about 150 days; wherein the second time period is from about 10 days to about 50 days; wherein the first time period is less than 120 days; wherein the second time period is less than 40 days; wherein the first time period is less than 120 days, and wherein the percentage of sulfide oxidized is greater than 20%; wherein the first time period islless than 120 days, and wherein the percentage of Sulfide oxidized is greater than 20%; wherein the first time period is less than 120 days, and wherein the percentage of sulfide oxidized is at least 20%; wherein the second time [ period is less than 40 days, and wherein the percentage of sulfide oxidized is at least i I

20%; and wherein the second time period is less than 40 days, and wherein the percentage of sulfide oxidized is greater than 20%; wherein the second time period is less than 40 days, and wherein the percentage of sulfide oxidized is at least 20%.

[0028] Still further, there is provided these Systems and methods having one or more of the following features: wherein the métal is selected from the group consisting of gold, silver and cooper; and wherein an oxidizing pH moderating material is selected from the group consisting of trôna, soda ash, and sodium nitrate.

[0029] In addition, there is provided a method of recovering a precious métal from an ore having: forming an aqueous layer on the surface of a particle of the ore; the aqueous layer having an oxidizing pH moderating material, wherein the oxidizing pH moderating material buffers the aqueous layer; the aqueous layer defining a surface expose to air; wherein an oxidation reaction is carried out in the aqueous layer; there after the ore particle is subjected to heap leaching for extraction of the precious métal from the ore.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 is a chart illustrating the effect of oxidation on leach recovery for ore from Domain Delta in accordance with the présent inventions. The x-axis being % recovery and the y-axis being % sulfide sulfur oxidation.

[0031] FIG. 2 is a chart illustrating the effect of oxidation on leach recovery for ore from Domain Beta in accordance with the présent inventions. The x-axis being % recovery and the y-axis being % sulfide sulfur oxidation.

[0032] FIG. 3 is a chart illustrating the percent recovery of Gold vs oxidation time in days, forfive different ore samples, to achieve 70% recovery, in accordance with the présent inventions. '

[0033] FIG. 4 is a schematic diagram showing an embodiment of a System and process flow for recovering metals from sulfide ores and transition ores in accordance with the présent inventions.

[0034] FIG. 5A is a chart showing an embodiment of percentage gold recovery vs percentage oxidation, from trôna applications, in accordance with the présent inventions.

[0035] FIG. 5B is a chart showing an embodiment of percentage silver recovery vs percentage oxidation, from trôna applications, in accordance with the présent inventions.

[0036] FIG. 6 is a chart showing an embodiment of percentage gold and silver recovery from an oxiclation-leach recovery System, in accordance with the présent inventions.

[0037] FIG. 7 is an illustration of embodiments of reactions used in oxidationleach recovery methods and Systems, in accordance with the présent inventions.

[0038] FIG. 8A is a chart showing an embodiment of the elapsed time in days vs percentage oxidation of a sulfide ore in accordance with the présent inventions.

[0039] FIG. 8B is a chart showing an embodiment of the leach time in days vs recovery of gold and silver for a sulfide ore in accordance with the présent inventions.

[0040] FIG. 9 is a pair of charts showing percentage oxygen vs elapse days and percentage recovery vs leach time for an embodiment of an oxidation-leach recovery methods in accordance with the présent inventions.

[0041] FIG. 10 is a pair of clJarts showing percentage oxygen vs elapse days and percentage recovery vs leach time for an embodiment of an oxidation-leach recovery methods in accordance with the présent inventions.

[0042] FIG. 11 is a pair of charts showing percentage oxygen vs elapse days and percentage recovery vs leach time for an embodiment of oxidation-leach recovery methods in accordance with the présent inventions.

[0043] FIG. 12 is a pair of charts showing percentage oxygen vs elapse days and percentage recovery vs leach time for an embodiment of oxidation-leach recovery methods in accordance with the présent inventions.

[0044] FIG. 13 is a chart showing percent recovery vs percentage sulfur oxidation for an embodiment of an oxidation-leach for oxidation-leach recovery methods in accordance with the présent inventions.

[0045] FIG. 14 is a chart showing percent recovery vs percent oxidation for an embodiment of an oxidation-leach for oxidation-leach recovery methods in accordance with the présent inventions.

[0046] FIG. 15 is a chart showing percent recovery vs percent oxidation for an embodiment of an oxidation-leach for oxidation-leach recovery methods in accordance with the présent inventions.

[0047] FIG. 16 is a chart showing an embodiment of alkalinity vs cumulative g of added, in accordance with the présent inventions.

[0048] FIG. 17 is a chart showing trôna consumption vs days for an embodiment of an oxidation-leach for oxidationl-leach recovery methods in accordance with the présent inventions.

[0049] FIG. 18 is a chart showing cyanide consumption vs days for an embodiment of an oxidation-leach for oxidation -leach recovery methods in accordance with the présent inventions.

[0050] FIG. 19 is a chart showing lime consumption vs days for an embodiment of an oxidation-leach for oxidation-leach recovery methods in accordance with the présent inventions.

[0051] FIG. 20 is a chart showing reagent consumption vs days for an embodiment of an oxidation-leach for oxidation-leach recovery methods in accordance with the présent inventions.

[0052] FIG. 21 is a schematic for an embodiment of a System and method for oxidation-leach recovery in accordance with the présent inventions.

DESCRIPTION OFTHE PREFERRED EMBODIMENTS

[0053] In general, the présent inventions relate to mining and industrial séparation Systems and processes for recovery' of minerais, including precious metals.

[0054] Generally, embodiments of the présent inventions relate to Systems and methods for oxidizing and leaching transitional and sulfidic material in a heap leach application.

[0055] In an embodiment of the présent processes, an ore containing a minerai is mined from the ground, if needed the ore can be crushed to a prédéterminé particle size and distribution. The ore is then subjected to a first Chemical treatment, in which the ore is contacted a first moiety and a second moiety. The first moiety reacts with the minerai forming a mineral-first moiety reaction complex. This mineral-first mciiety reaction complex is carried by a fluid, typically \dater, away from the ore.

[0056] The second moiety performs one or more functions, including for example, a buffer, pH control, a pH buffer, a competing reactant and one or more or ail of these. Thus, in one aspect, whether because of concentration, reaction kinetics or other reasons, the second moiety is more likely to react with one or more undesirable materials in the ore, than is the first moiety. In this manner the second moiety minimizes, mitigates, or prevents the undesirable materials in the ore from reacting with the first moiety, or otherwise being used up by or rendered in effective (chemically, economically or both) by the undesirable materials.

[0057] The addition of the first moiety and the second moiety can be at the same time, or same stage, in the process or they can be at different times or stages in the process. Thus, the second moiety can be added as a dry component with the ore, can be added to the ore as part of liquid solution, e.g., aqueous solution, or both. The second moiety can be rinsed away, or otherwise removed from the ore (after its intended reaction has taken place), before the addition of the first moiety. The use of the term “first” and “second” does not require a particular timing for the use of these moieties in the process. Thus, the first can be used later in the process than the second, they can be used at the same time or stage, the second can be used later in the process than the first, and combinations and variations of these.

[0058] The mineral-first moiety complex in the fluid is then subjected to further treatment (Chemical, thermal, or both) where minerai is removed (e.g., separated, removed, extracted, etc.) from the first moiety. Typically, this removal, or second step, is conducted after the fluid with the mineral-first moiety complex is carried away from the ore, e.g., flowed into a separate holding basin, pond, structure, tank, or location in the System or plant. Typically, after removal the minerai can then be washed, concentrated, collected and one or more of these and other processing steps.

[0059] The embodiments of the présent pre-oxidation then CN-leach processes (e.g., “oxidation-leach” technologies) can use soda ash as the second moiety. Soda ash (sodium carbonate) is an acid neutralizer that has a much higher solubility than lime. Its natural precursor is trôna, which is a 1:1 mixture of soda ash and sodium bicarbonate. Its solubility is about 12% at room température. In contrast, lime has a solubility of 0.08%. Trôna, because of its higher solubility! can deliver five times or more neutralizing power compared to lime alone and due to the sodium ion in Trôna, instead of the calcium, ion in lime, it does not form calcium carbonate and is less likely to precipitate. For a sulfide leach pad, trôna is therefore five times more effective than lime i i in de-risking the heap leach operations from pH loss. A sodium rich System also offers the benefit of not armoring or passivating the pyrite surfaces addressing a long-standing problem which occurs in a lime System. Sodium carbonate works to keep the pyrite surfaces clean, due to the carbonate effect. Carbonate in solution keeps the sulfide surfaces clean during oxidation, improving the oxidation rate compared to other neutralizing agents.

[0060] The embodiments of the présent oxidation-leach technologies can use trona-lime combinations as the second moiety. In a trona-lime neutralizing System, the barren cyanide solution sent to the heap will contain cyanide species and essentially a carbonate-bicarbonate solution where the carbonate to bicarbonate ratio is 1. This ratio will ensure a pH of 10.3 due to the bicarbonate-carbonate buffer formed naturally by Na2CO3-NaHCOs. As the trôna in solution neutralizes acid in the heap, a portion of the carbonate (COs2-) will be converted to bicarbonate (HCO3-), which changes the ratio. The pH change in the prégnant cyanide solutions will be controlled by the carbonatebicarbonate buffer, typically as long as an excess of trôna is présent. In addition, prior to return of the barren solution to the heap, the ratio of carbonate to bicarbonate can be restored to 1 by adding hydrated lime (régénération). Hydroxide reacts with bicarbonate to convert it to carbonate, and calcium reacts with sulfate and carbonate to precipitate gypsum and calcite.

[0061] Embodiments of the oxidation-leach technologies of the présent inventions include Atmospheric Alkaline Oxidation (“AAO”) to pre-oxidize pyrite in sulfide and transition ore flotation concentrâtes and achieve commercial CN leach recoveries in a standard flotation and conventional cyanidation of the oxidized concentrate. Thus, embodiments utilize a carbonate assisted (Trôna) pyrite oxidation technology to allow commercial cyanide leach recovery of gold and silver in a sulfide heap leach (SHL) application. It is theorized that it is the ferrous/ferric couple chemistry that drives the oxidation in this embodiment and it is made possible in alkaline environments by th^ use of Trôna based solutions. I

[0062] In an embodiment of an oxidation-leach methodology, unstable pyrite mineralogy that oxidizes rapidly, namely pyrite/marcasite is used. A rate affecting and potentially limiting category in SHL pyrite oxidation is the ability to produce physical exposure of the pyrite in commercial heap leach crush sizes and achieve économie gold and silver recoveries from the extent of oxidation possible. Pyritic ores provide opportunity for this as the mineralogy Controls are favorable to a coarse crushed exposure of the targeted enriched pyrite. Thus, in this embodiment, unlike low-grade sulfide resources in epithermal deposits, it is preferred to hâve ores that demonstrate predominantly fracture-controlled sulfide mineralization. As such, the ore consistently breaks as shearing along these fracture planes that host the pyrite mineralization at the coarse crush sizes commercially practical for heap leach models. Liberation of the more friable fine-grained marcasites occurs on these fracture shears during coarse crushing and the larger pyrite crystals in the fracture shears, not fully liberated, présent faces available for attack with oxidizing solution.

[0063] In embodiment of an oxidation-leach methodology, the gold enrichment pyrites exists predominantly in the form of rimming on the pyrite, rather than as inclusions or in solid solution through the core of the pyrite. It is theorized that because of this, commercially viable cyanide extraction from the gold enriched rims with just partial oxidation of the pyrite content is obtained. Thus, oxidation of the barren core of the minerai to gain cyanide leachability of the gold deposited along grain boundaries is not required. A partial oxidation of the pyrite at the surfaces returns gold recoveries that are disproportionately higher than the pyrite oxidation required to achieve them.

[0064] Embodiments of these processes can be performed in Systems or plants that provide the capability for conducting the treatments, reactions and removal activities of the processes. Thus, for example, these processes can be conducted in heap leaching Systems, in situ mining Systems, flotations Systems, vat leaching Systems, lagoon Systems, tank Systems, and other batch and continuous Systems. Embodiments of the présent Systems and methods can be performed on many types of ores and minerai deposits, including: epithermal deposits, low sulfidation deposits, hot springs deposits, disseminated deposits, vein-controlled deposits, oxide ores, transitional ores, sulfide ores, and combinations and variations of these and other types of ore^ and dépositions.

[0065] Depending upon the reactions taking place, the density of the ore, the volume of ore, the concentration of the minerai, and other factors, the ore can be in ! i particle or piece sizes of from about 1 pm to about 1,000 mm, from about 50 pm to about 300 pm, from about 0.1 mm to about 0.5 mm, from 0.25 mm to about 2 mm, from about 2 mm to about 64 mm, from about 4 mm to about 32 mm, from about 8 mm to about 16 mm, from about 16 mm to about 50 mm, from about 60 mm to about 260 mm, as well as ail sizes within these ranges, and larger and smaller sizes. These sizes can be for the individual particles or pièces of ore used in the process, they can be the largest particle size where ail others are smaller (sieve distribution), they can be an average particle size, they can be a Dso particle distribution (the size of the particles making up 50% of the total particle size population), or they can be a distribution where 80% of particle sizes are smaller than these sizes.

[0066] In embodiments, the ability of oxygen, for example from air, to contact the ore during the process, can be important and depending upon the reaction needed. Oxygen can be a react in the one or more of the steps of the présent processes. While oxygen can be dissolved in the fluid used to carry the moieties, the amount of oxygen that can be carried is limited, e.g., water can carry about 9 mg/L at 20 °C. Thus, the amount of fluid, e.g., aqueous solution of water and first and second moiety, on the ore should be less than the amount that completely saturâtes the ore. In this manner the ore that is being treated in the présent process can be at about 80% to 99% saturation, (i.e., saturated with the fluid); about 85% to about 95% saturation, and preferably 95%, 96%, and from 97% to 98% saturation, as well as ail percentages within these ranges and higher and lower percentages. As used herein “saturated” and “saturation” are given their common meaning, and thus include the maximum amount of water that the ore can absorb or hold. It being understood that the fluid can be also be oxygenated (e.g., oxygen is added to the fluid), that the ore can be mechanically configured (e.g., beds in a reactor), other sources of oxygen can be provided in the fluid, or may be added to, or présent in, the ore itself, and combinations and variations of these.

[0067] The recovery of métal, e.g., gold or silver, to oxidation ratio (%recovery / %oxidation), in embodiments, can Le affect by, and preferably increased by, the particle sizes used in the process. Grinding ore particles into smaller fractions serves to increase the exposed surface area of sulfide that can be oxidized, but also créâtes oxidation sites that do not serve to liberate gold once oxidized. Thus, for smaller grind sizes, e.g., less than 0.5 inches, and less about 0.25 inches, a greater degree of oxidation must be achieved in order to achieve recoveries that are similar to recoveries achieved in larger grind sizes, e.g., 0.5 inches to about % inches, under otherwise similar conditions.

[0068] A factor in obtaining good oxidation % and good recover % is the degree of permeability in the ore bed, and maintaining that permeability during processing. Preferably in embodiments good permeability is maintained in the ore bed during oxidation and leaching. Bed permeability maximizes the exposure of sulfides to oxygen during oxidation, and to the leach solution during the leach stage. This suggests that, during operations, close attention to the crush size of the ore would be bénéficiai, as well as controlling the proportion of coarse to fine materials. For the two-step process, e.g., peroxiclation and leach, maintaining permeability is bénéficiai for, at least, the following reasons:

[0069] First, the short leach cycle can better be achieved if the ore is sufficiently oxidized. The process is premised upon a long oxidation period that is rewarded with fast leach kinetics. If the required oxidation is not achieved, the sulfide and transition ore leach kinetics will become slow, hurting the économies of the process.

[0070] Second, oxidation should occur during the pre-oxidation stage where there will be sufficient neutralizer présent. One goal is to oxidize the bulk of the sulfide sulfur such that the remaining sulfide sulfur is low enough in concentration and slower oxidizing. The rate of acid production during the leach cycle would then be too slow to overwhelm the protective alkalinity in the cyanide leach solution.

[0071] Third, permeability permits more efficient wash down of the residual carbonates in the heap and maximize contact between the oxidized ore and the leaching solution.

[0072] Embodiments of the process and System can be used to process large amounts of ore, in a semi-continuous, continLous or batch process. Thus, the process can process about 50 to about 10,000,000 tons, about 50 tons and more, about 100 tons and more, about 1,000 tons and more, about 10,000 tons and more, about 100,000 tons and more, about 1,000,000 tons and more, about 10,000,000 tons or more, as well

I as ail amounts within these ranges, and greater and smaller amounts.

[0073] The amounts of ore can form heaps that are built in, or hâve several layers of material, with each layer having a height of about 1 m to about 20 m, about 5 m to about 10 m, about 6 m, as well as ail heights within these ranges, and greater and smaller amounts. Thus, the total height of a heap, can be from about 4 m to about 40 m, about 5 m to about 20 m, about 6 m to 30 m, about 10 m to about 25 m, as well as ail heights within these values and larger and smaller amounts.

[0074] In embodiments, the fluid carr/ing the moieties may be applied to the ore, in such a heap, through a number of cycles, e.g., leach cycles. Each leach cycle can last from about 30 days to about 500 days, about 50 days to about 300 days, about 100 days to about 200 days, about 50 days to about 150 days, about 75 days, about 90 days, about 120 days, as well as ail values within these ranges and greater and smaller 10 times. In embodiments, the fluid can be to the ore at rates of from about 1 L/hr/m² to about 50 L/hr/m², about 5 L/hr/m² to about 25 L./hr/m², about 8 L/hr/m² to about 20 L/hr/m², about 9 L/hr/m² to about 12 L/hr/m², as well as ail rates within these ranges, and larger and smaller rates. One, two, three, or more leach cycles can be applied to a particular heap of ore. Additional ore can also be added to the heap between leach 15 cycles.

[0075] Leach pads are under these heaps (e.g., the ore is placed on top of the pad as the head is built), and collection Systems, e.g., pipes, channels, conduits, to collect the fluid after it percolates through the ore and contains the mineral-first moiety complex.

[0076] In embodiments, the sulfide minerais can contain gold, silver, copper, or uranium.

[0077] In an embodiment, the processing of the run-of-mine oxide and transition ores is conducted. Oxide and transition ores that will be crushed before ^tacking on the heap leach pad. Ail sulfide ore in the|mine will be crushed, oxidized and 25 leached. Some transition ores may use the sulfide protocol. Oxidation of sulfide ores is accelerated in the presence of carbonate, which may be supplied by trôna or soda ash. Resulting cyanide leach recovery of these oxidized sulfide ores yields about 70% to 85% recovery. In essence, the oxidation of sulfide and transition ores converts them into oxide ores.

[0078] In an embodiment control parameters in the oxidation process, among others, are pH and oxygen availability. The oxidation is conducted in the presence of sufficient trôna or soda ash to keep the pH near the buffer région between carbonate and bicarbonate (pH 10.3). At this pH régime, ferrous and ferrie carbonate complexes become stable and provides a carbonate complex version of the Fe(ll)/Fe(lll) couple. During operations, iron ions will already be présent in the recycled carbonate solutions which should initiate the reaction. Oxygen is the ultimate oxidizer in the process. Natural air pockets are formed during stacking of the ore and maintained during the oxidation phase and the leach phase. The ore is just wet enough to promote the reactions that occur in aqueous phase while keeping the interstices in the stack open for air to occupy. 60, 90 and 120 day oxidation times are used. These time times may be shorter if the presence of iron in recycled carbonate solutions is exploited, provided permeability of the ore stack is maintained.

[0079] In embodiments, in particular for the recovery of gold or silver from ore, the first moiety can be a CN (Cyanide) solution, which preferably has lime, and the second moiety can be a mixture of soda ash (Na2CO3) and sodium bicarbonate (NaHCOs), the mixture can be from about 20% soda ash to about 80% bicarbonate, from about 80% soda ash to about 20% bicarbonate, from about 40% soda ash to about 60% bicarbonate, from about 60% soda ash to about 50% bicarbonate, and about 50% soda ash and 50% bicarbonate, about 60% carbonate and 40% bicarbonate, as well as, ail ratios within these ranges, and larger and smaller percentages. Trôna (trisodium hydrogendicarbonate dihydrate) (Na2CO3«NaHCO3*2H2O) is a preferred second moiety for use in processing gold containing ores. Other oxidizers may also be used as the second moiety, or in conjunction with, soda ash, bicarbonate, mixtures of soda ash and bicarbonate, and trôna. For example, the second moiety can be Sodium Nitrate.

[0080] Trôna is a naturally occurring evaporite minerai with the Chemical formula ha2CO3NaHCO3-2H2O. The largest known deposit ol trôna in the world is found in the Green River formation of Wyoming and Utah. During the atmospheric oxidation, trôna provides neutralizing capacity for the acid produced when sulfides are oxidized in a slurry. _i Both the carbonate and bicarbonate species can react with acid, depending on availability and pH. The oxidation and acid neutralization can be represented by the following reactions:

FeS₂ + 4 Na₂CO₃ + 2.5 H₂O + 3.75 O_2(g) = FeOOH + 2 Na₂SO₄ + 4 NaHCO₃ AG° = -357.453 kcal/mol FeS2 + 4 NaHCO₃ + 3.75 O_2(g) = FeOOH + 2 Na₂SO₄ +1.5 H₂CO₃(_a) + 2.5 CO AG° = -329.434 kcal/mol

[0081] The oxidation process for sulfide concentrâtes is preferably conducted at elevated températures, but below boiling, to maximize the reaction rate. The reaction may be carried out to neutral pH to minimize lime neutralization requirement prior to cyanidation, orto the extinction of carbonate and bicarbonate in solution to optimize trôna consumption. It is possible to carry out the reaction to very acidic pH but this may lead to the formation of jarosites.

[0082] It is theorized that the Fe3+/Fe2+ couple may play a rôle in the oxidation process. Initially, it was thought that trôna played purely a neutralizing duty. However, preliminary results of exploratory experiments suggested that trôna may be speeding up the oxidation reaction. This finds support in testing results. Oxidation tests conducted in columns of crushed ore show that the presence of trôna accelerated the oxidation process at ambient températures. The mechanism proposed for this process involves the catalytic effect of the ferrie and ferrous redox couple, where ferrie and ferrous ions are stabilized in solution by carbonate or bicarbonate. Table 1 below is a list of carbonyl or bicarbonyl complexes that hâve been identified as stable in non-acidic solutions in the présences of high concentrations of carbonate or bicarbonate.

[0083] Table 1

Ferrous Complexes	Ferrie Complexes
FeHCO3 +	Fe(CO3)2'
FeC03(aq)	FeC03 +
Fe(CO3)2 2'
Fe(OH)CO3

[0084] t is theorized that the basic model for an embodiment of the présent carbonate assisted pyrite oxidation solution involves a redox System driven at the pyrite face by the ferric/ferrous couple System. Further, the reaction rate mây be limited by one of three factors: 1) ferrous iron solubility in alkaline solution; 2) the carbonate concentration; and 3) the available dissolved oxygen to regenerate ferrous to ferrie. This mechanism is illustrated in FIG. 7

[0085] Thus, it it theorized that, in embodiments, the ferrous/ferric couple is the driving force of pyrite oxidation at the surface of the crystal. This couple serves to bridge the solid State pyrite face to the oxidation solution and carry électrons from the pyrite face into solution where the dissolved oxygen is much more efficient to take over as the électron sink to the solution redox system. Dissolved oxygen is not an efficient oxidizer of solid State materials like pyrite. Electrostatic and gas/solid phase boundaries do not lend to efficient électron transfer (oxidation) from the pyrite solid face to iron cation release to solution. Ferrie iron has long been recognized as a superior oxidizer of pyrite (and ail other métal sulfides). This is owed to its ability to participate in surface bonds with the iron disulfide and create an intimate bridge interface from solid surface to solution for électrons to be transported into solution redox Systems. It should be noted that no iron is oxidized by the ferric/ferrous couple into solution. The ferrie ion oxidation of pyrite is eentered on the attack of the sulfur leg, releasing the pyrite ferrous ions into solution as the pyrite dégradés. Once deported to solution as a mobile iron cation, dissolved oxygen is then able to oxidize the ferrous ions to ferrie ions (iron pump) and, thus, replenish the ferrie available to pull électrons (oxidize) from the pyrite surface to solution and complété the cycle. This oxidation system, is made possible in the sulfide heap leach by the ability of trôna to allow this redox cycle in an alkaline environment.

[0086] In embodiments, and given the iron pump reaction pathway, trôna is used as a carbonate based sulfide oxidizing solution. Because the oxidation of ferrous ions in solution by dissolved oxygen complétés the ferric/ferrous couple cycle, the first rate limiting factor is the solubility of ferrous ions in the solids wetting solution. In a standard hydroxide (lime) commercial alkaline system, ferrous iron solubility between the pH ranges of 7 and 1 j is very near zéro due to the insolubility in a lime-ba^ed solution of ferrie hydroxide. In a lime based alkaline system, no ferric/ferrous couple cycling can occur as no ferrous/ferric ions can escape the insolubility of the ferrie hydroxide solid, effectively killing the redox potential of this efficient pyrite solvent.

i

However, in a carbonate based alkaline solution, ferrous/ferric solubility is restored to the solution with iron carbonate complexes. These ferrous and ferrie carbonate complexes maintain solubility in the pH ranges required for the CN leaching of the oxidized pyrites. However, the solubility of these iron carbonate complexes in commercial CN pH ranges requires alkalinity levels (dissolved carbonate concentrations) of 15,000 - 25,000 ppm in the solvent solution. Trôna (Na2COs) is a preferred carbonate as it is soluble to 10%+ on leach solutions at our ambient températures, providing not only the alkalinity buffer to de-risk acid génération issues in Sulfide Heap Leach (SHL) commercial pH ranges, but provides the carbonate assisted solubility of the ferrous/ferric couple pyrite oxidation System in this same pH range. Trôna provides a low cost, risk averse alkalinity source option for SHL. It can be solution delivered throughout the heap and allows sufficient ferrous/ferric carbonate solubility at commercial CN pH ranges to utilize the pyrite oxidation enhancement of the ferrous/ferric couple System at the pyrite faces. In embodiments, ferrous solubility is optimum at 15,000-20,000 ppm carbonate alkalinity (approx. 1.5% trôna solution), and that pyrite reactivity to oxidation is also optimum at the pH range this level of trôna concentration delivers.

[0087] In embodiments, and given the iron pump reaction pathway, another factor to complété the ferrous/ferric couple oxidation of pyrite is dissolved oxygen. To complété the ferrous/ferric couple redox cycle, there is a stoichiometric balance of dissolved oxygen to convert dissolved ferrous ion to ferrie State. Sparging of O2 gas in an application of AAO is a factor in the high oxidation rates, which translate to high recovery rates. However, in SHL applications where the ability to replenish dissolved oxygen levels through surface diffusion to replace O2 consumed in the ferrous/ferric redox cycle with pyrite is limited, other ways to obtain the required dissolved oxygen levels can be used. Thus, for example, holding a wetting level of solution between 8-10 percent to maintain highly alkaline pore carbonate solution holds, while allowing maximum air to solution surface contact such that maximum availability of oxidation I System dissolved oxygen is maintained can be used. This can be viewed as allowing the heap to “breath.” i Examples

[0088] The following examples are provided to illustrate various embodiments of Systems, processes, compositions, applications and materials of the présent inventions. These examples are for illustrative purposes, may be prophétie, and should not be viewed as, and do not otherwise limit the scope of the présent inventions.

[0089] EXAMPLE 1

[0090] Using a sulfide ore, Atmospheric Alkaline Oxidation (AAO) pre-oxidizes 5 pyrite ore flotation concentrâtes and achieves 70% or greater CN leach recoveries in a standard flotation and conventional cyanidation of the oxidized concentrate mill flow System.

[0091] Using sulfide ore, a larger scale System and process utilizes carbonate assisted, in this example, Trôna based pyrite oxidation methodology to achieve the 10 cyanide leach recovery of gold in a sulfide heap leach (SHL) application for two 5,000 ton test heaps, with leach of 60 days. High levels of leach recoveries are obtained.

[0092] Thus, there are commercially viable recoveries when utilizing Trôna as an oxidation enhancement agent and acid mitigating alkalinity source.

[0093] EXAMPLE 2

[0094] In a trona-lime neutralizing system, for a sulfide ore, the barren cyanide solution sent to the heap contains cyanide species and essentially a carbonatebicarbonate solution where the carbonate to bicarbonate ratio is 1. This ratio ensures a pH of 10.3 due to the bicarbonate-carbonate buffer formed naturally by Na2CO3NaHCOs. As the trôna in solution neutralizes acid in the heap, a portion of the carbonate (CO3 ²) converts to bicarbonate (HCO3 ), which changes the ratio. An excess of trôna is présent, such that the pH change in the prégnant cyanide solutions is controlled by the carbonate-bicarbonate buffer. Prior to return of the barren solution to the heap, the ratio of carbonate to bicarbonate can be restored to 1 by adding hydrated lime. Hydroxide reacts with bicarbonate to couvert it to carbonate, and calcium reacts with sulfate and carbonate to precipitate g^/psum and calcite.

[0095] EXAMPLE 3

[0096] Heap leach oxidation and cyanide leach tests are performed on traditional lab columns. Core samples for metallurgical testing were selected to represent domains

I within an orebody. Taking samples from four ore domains, tests were conducted in plexiglass cylindrical columns that were 1 ft diameter and 4 ft high. Ore samples were crushed to 1/2 inch, blended and loaded into the columns.

[0097] Oxidation was performed for 60, 90 or 120 days by adding trôna to the ore column and applying just enough solution to the column to keep the ore wet. Only enough solution drains at the bottom of the column to use for conditions measurement. This status is maintained to ensure that the interstices in the ore column are filled with oxygen-supplying air and not flooded with solution. Thus, the ore in the column is kept below saturation levels. A 50-ml sample was collected each day for pH and sulfate analysis. Oxidation was tracked by the amount of sulfate produced.

[0098] At the end of the oxidation cycle, the column is rinsed to recover sulfate held in the column ancl to wash down as much carbonate and bicarbonate out of the column as possible. This is followed by a lime wa.ter rinse, which will ensure that any remaining carbonate is precipitated as CaCOa. The column then undergoes a standard cyanide column leach.

[0099] The results of the column oxidation followed by leach tests in general show that higher oxidation levels produce better gold and silver recoveries in the subséquent cyanide leach process. This can be seen for Domain Delta and Domain Beta ores (FIG. 1 and FIG. 2, respectively).

[00100] As seen in FIG. 1, Domain Delta ores exceeded the 70% recovery target with oxidation levels of about 25% with 60 days of oxidation. Two Columns attained 85% and 75% gold recoveries, respectively. For Domain Beta, as seen in FIG. 2, leach recoveries were on target to reach 70%, despite the seemingly low oxidation levels. Also évident in the results for Domain Beta is the lower gold and silver recoveries achieved for samples taken below the water table. Generally, the recovery of precious métal can be the same for ore that is above, at and below the water table. In embodiments, the time required to oxidize the pyrite, for materials below, and at the water table can be longer than from materials above the water table. It is thdorized that this is most likely due to the size of the pyrite. However, typically, oxidation rates are equal below and above the water table.

[00101] EXAMPLE 4 i

[00102] Turning to FIG. 3 there is shown the time in days for oxidizing five different ore samples to reach 70% Gold recovery. This Example suggests that 60%, and 70% recoveries can be achieved in most types of sulfide ores and transitions ores in 140 days of oxidation time or less, and that recoveries of 80% and greater can be obtained given sufficient oxidation times.

[00103] The oxidation times, for sulfide ores, to reach 70% recovery (or more) by standard CN leach process, can be less than about 40 days, less than about 60 days, less than about 100 days, and less than about 160 days, from about 40 days to 60 days, from about 30 days to 50 days, from about 60 days to about 120 days, and ail times within these ranges, as well as shorter and longer times.

[00104] The oxidation times, for transitional ores, to reach 70% recovery (or more) by standard CN leach process, can be less than about 40 days, less than about 60 days, less than about 100 days, and less than about 160 days, from about 40 days to 60 days, from about 30 days to 50 days, from about 60 days to about 120 days, and ail times within these ranges, as well as shorter and longer times.

[00105] EXAMPLE 5

[00106] Silver recovery for transition and sulfide ore material is not as dépendent on oxidation time as is Gold recovery. Particle size and mineralization (primarily ore below the water table) hâve more of an effect with respect to recovery. Silver recovery, including average recoveries, of more than 60%, more than 70%, more than 80% is expected for transition and sulfide material.

[00107] EXAMPLE 6

[00108] Gold recoveries using the présent oxidation process from sulfide ore materials are from 50% to 85%, from 60% to 90%, from 60% to 75%, from 65% to about 75%, from about 70% to 85%, and ail recoveries within these ranges, as well as higher and lower ranges.

[00109] EXAMPLE 7 l[00110] Gold recoveries using the présent oxidation process from transitional ore materials are from 50% to 85%, from 60% to 90%, from 60% to 75%, from 65% to about 75%, from about 70% to 85%, and ail recoveries within these ranges, as well as higher and lower ranges.

[00111] EXAMPLE 8

[00112] Silver recoveries using the présent oxidation process from sulfide ore materials are from 50% to 85%, from 60% to 90%, from 60% to 75%, from 65% to about

75%, from about 70% to 85%, and ail recoveries within these ranges, as well as higher and lower ranges.

[00113] EXAMPLE 9

[00114] Silver recoveries using the présent oxidation process from transitional ore materials are from 50% to 85%, from 60% to 90%, from 60% to 75%, from 65% to about 75%, from about 70% to 85%, and ail recoveries within these ranges, as well as higher and lower ranges.

[00115] EXAMPLE 10

[00116] Turning to FIG. 4, there is shown a layout and process flow diagram illustrating an embodiment of a System and method of the oxidation then cyanide processes to extract valuable metals, e.g., gold and silver, from sulfide ore, transitional ore, and combinations and variations of these, and other ores.

[00117] The System has a primary crushing segment or plant 100. The ore material is feed into and crushed by the primary crushing plant 100. The crushed ore is stored in crushed ore storage pile 101. The crushed ore is feed to a secondary crushing segment or plant 102 (preferably having both screens, e.g., screening apparatus, and crushers), and from the secondary crushing segment to a tertiary crushing segment or plant 103 (preferably having both screens, e.g., screening apparatus, and crushers), which produces a crushed ore storage pile 104. Ore from the crushed ore storage pile 104 is feed to the heap leach segment 106. There is a “carbonate assisted oxidation and mitigation” handling and distribution segment 107. There is a métal recovery segment 108 for recovering the métal from the solution leaving the heap leach segment 106.

[00118] The carbonate assisted oxidation and mitigation reagent is trôna (trisodium hydJogendicarbonate dihydrate, sodium sesquicarbonat^ dihydrate, Na2CO3*NaHCO3*2H2O), soda ash (sodium carbonate, Na2CO3), bicarbonate (NaHCOs), and combinations of these, and other oxidizing agents. In an embodiment the carbonate assisted oxidation and mitigation reagent is at least about 60% soda ash, at least about 80% soda ash, 95% soda ash, and 100% soda ash.

[00119] It being understood that in embodiments, one or more of the segments may be combined into a single segment or plant.

[00120] EXAMPLE 10A

[00121] The crushing System 100, in the precious métal from ore recovery System of Example 10 and FIG. 4, runs at a nominal capacity of from about 30,000 stpd to about 100,000 stpd, from about 40,000 stpd to about 80,000 stpd, about 60,000 stpd, about 70,000 stpd, and ail values within these ranges, as well as larger and smaller amounts. Pit ore is routed to the primary crusher dump pocket via haul truck where it is crushed to 7” (inch). Prior to the primary crusher each truck being routed is passed under a carbonate assisted oxidation and mitigation material silo where a pre-determined amount of dry material is be added to the ore. For example, trôna or soda ash is added to the ore in each truck prior to the crushing System. The ore is processed through three stages of crushing to exit the tertiary crushers at a nominal P80 crush size of approximately 0.5 inch depending on the ore routing. The crushed ore is then stacked for use or application on the heap leach pads in the leach pad segment 106.

[00122] EXAMPLE 10B

[00123] Pre-oxidation of sulfide ore, transition ore or both (preferably crushed to about 0.5”), in the precious métal ore recovery System of Example 10 and FIG. 4, begins at the crushers using in-situ moisture and carbonate assisted oxidation and mitigation material. The carbonate assisted oxidation and mitigation material requirement for the ore is relative to the percent sulfide-sulfur content of the ore. Typically, the average carbonate assisted oxidation and mitigation material consumption is from about 5 Ibs per ton to about 50 Ibs per ton, from about 10 Ibs per ton to about 40 Ibs per ton, about 15 Ibs per ton to about 25 Ibs per ton, about 15 Ibs per ton, about 20 Ibs per ton, about 25 Ibs per ton, and ail values within this range, as well as longer and smaller amounts.

[00124] Once ore has been placed on the heap leach of segment 106, additional carbonate assisted oximation and mitigation material solution will be applied Ito bring the ore to field capacity (about 8 -10% moisture). The solution in the heap will be replenished on a regular basis using carbonate assisted oxidation and mitigation material solution in order to offset évaporation and carbonate consumption. For example, a trôna or soda ash i i solution is added to the leach heap on a regular basis. Carbonate assisted oxidation and mitigation material solution is pumped through a separate System of pipes or tubing from the lixiviant solution System.

[00125] Pre-Oxidation duration can be determined by the characteristics of the ore and the measured extent of oxidation based upon sulfate production. To achieve métal recoveries or about 70% or greater, it is préférable to hâve at least about 45% oxidation prior to completion of the pre-oxidation stage. Typically, ore can take between 90 and 120 days to complété pre-oxidation.

[00126] Generally, in the System of Example 10 and FIG. 4, the pre-oxidation step is from the crusher 100 (or the haul truck where material is added to the ore) to the crushed pile 104. It being understood that carbonate assisted oxidation and mitigation material as dry or in aqueous solution can be added at other points between the crusher 100 and the crushed pile 104, as part, of the pre-oxidation step.

[00127] EXAMPLE 10C

[00128] Ore that has undergone a pre-oxidation cycle is rinsed, preferably with a saturated lime solution prior to the commencement of cyanidation leach. Saturated lime solution is applied to panels that hâve undergone pre-oxidation at a rate of from about 0.0005 to about 0.0100 liters/min*m², from about 0.0010 to about 0.0050 liters/min*m², about 0.0025 liters/min*m², ail values within these ranges, until about one pore volume has been displaced, about 1.5 pore volumes hâve been displaced, about two pore volumes hâve been displaced, about 2.5 pore volumes hâve been displaced, combinations and variations of these, and ail values within these ranges. This rinse removes the bicarbonate from the heap and prevent cyanide loss during leaching.

[00129] Preferably, alkalinity of the solution in the heap is monitored to ensure rinse completion prior to the start of cyanidation.

[00130] Rinse solution can be supplied using the same piping that delivers lixiviant during the leach phase or can be supplied using a separate or independent System. I I

[00131] EXAMPLE 10D

[00132] Typically, cyanidation conditions for ore can be the same regardless of crush size or the use of pre-oxidation. The duration that these conditions are maintained is dépendent on the category to which the ore belongs. The cyanide concentration of from about 0.5 Ibs/ton to about 3.5 Ibs/ton, about 0.75 Ibs/ton to about 2.25 Ibs/ton, about 1 Ib/ton to about 2 Ibs/ton, about 1.5 Ibs/ton, and ail values within these ranges, as well as large and smaller amounts, of solution will be maintained. The pH is be controlled using lime.

[00133] EXAMPLE 10E

[00134] Oxide and transition ore material can be leached as ROM (run of mine) and in this manner it can proceed directly from the pit to the heap. Cyanide leaching can begin without undergoing pre-oxidation or rinse. A small percentage of oxide and transition material will be directed to the crushing plant to be reduced to a P80 of about 0.75 before being stacked and commencing cyanide leach.

[00135] Transitional and oxide ore materials undergo a 200-day primary leach cycle using a 3:1 solution to ore ratio and an application rate of 0.0025 liters/min*m².

[00136] Sulfide material ore and a portion of the transition material ore are reduced to a P80 of 0.5” before undergoing the pre-oxidation and rinse processes on the heap. At the conclusion of the rinse a 100-day primary leach cycle will begin. A 1.5:1 solution to ore ratio and an application rate of 0.0025 liters/min*m² is used.

[00137] EXAMPLE 10F

[00138] Gold, silver and both, are recovered from the prégnant solution taken from the heap leach through any conventional means known to the art.

[00139] EXAMPLE 10G

[00140] The métal recovery segment can be any known Systems devices or process for the séparation of métal from métal complexes, slurries, and solutions. For ores, and thus prégnant solutions with high silver content, gold and silver can be recovered by zinc cementation. In the System of Example 10, FIG. 4, Merrill-Crowe plants 108, process the prégnant solution from the heap leach operation. These plants can hâve a capacity of from about 2,000 gpm to about 40,000 gpm, from about 4,000 gpm to about 30,000 gpm, from about 3,000 gpm to about 25,000 glpm, about 5,000 gpm, about 20,000 gpm, about 30,000 gpm, and ail values within these ranges, as well as larger and smaller values.

[00141] In an embodiment of this example, wet filter cakes from the low-grade and high-grade Merrill-Crowe circuits are transferred to retort pans, which are then put into i a retort furnace to remove water and mercury. Water and then mercury are sequentially volatilized from the precipitate by heating the precipitate under a partial vacuum. The exhaust gases pass through multiple stages of condensers that drain mercury and water to a collection vessel. The retorts are typically operated batch-wise, with a cycle time of approximately 18 hours. The dried filter cake is mixed with flux and then transferred to an electric arc furnace where it is smelted to produce dore.

[00142] EXAMPLE 11

[00143] In embodiments sodium sulfate, sodium bicarbonate and combinations of these build up to a steady State in the reclaimed water. In some embodiments, sulfate ions in water Systems, make up water, can slow down the sulfide oxidation reaction. These can be addressed by increasing oxidation times. Preferably, these can be addressed and mitigated by fresh water addition to the soda ash recycle pond to optimize, and preferably maximize the dilution of sulfate and bicarbonate ions in the pre-oxidation water circuit.

[00144] EXAMPLE 12

[00145] In an embodiment the heap, in a precious métal from ore recovery System, such as the System of Example 10, FIG 4, processes, one, two, three, four, five or more different categories of ore. These categories of ore include, for example, ail 15 metalliferous sulfide ores

[00146] EXAMPLE 13

[00147] In an embodiment the heap, in a precious métal from ore recovery System, such as the System of Example 10, FIG. 4, processes three different categories of ore.

[00148] Ore Category 1 (ROM ore) - low-grade ore with high cyanide soluble gold is cyanide leached to extract gold and silver. This accounts for from about 1 % to about 50%, and ail values within this range, or more, of the ore over the life of mine. The gold contents are highly soluble and the remaining refractory gold contents typically do not justify the time and expense of a pre-oxidation step, therefore it will be stacked as 'ROM¹. The ore in this category is typically referred to as, ROM ore, ROI\I/I 'oxide' or ROM 'transition'.

[00149] Ore Category 2 (3/4 Crushed ore) - high-grade ore with high cyanide soluble gold is crushed to a P80 of 3/4 and cyanide leached to extract gold and silver. This accounts for about 1% to about 50%, and ail values within this range, or more, of the ore i over the life of mine. The gold contents are highly soluble, and additional size réduction is expected to increase gold and silver recovery enough to justify the additional expense. The remaining refractory gold contents are not projected to justify the time and expense of a full pre-oxidation cycle. The ore in this category is typically defined as 3/4 Crushed 'oxide' or 'transition'.

[00150] Ore Category 3 (1/2 Crushed ore) - low cyanide soluble ratio ores are crushed to a P80 of 1/2. The crushed ore is mixed with soda ash, trôna or a mixture of both, to induce an alkaline 'pre-oxidation' process. After the oxidation process has been completed to the desired extent, the ore will be 'rinsed' with saturated lime solution and then cyanide leached to extract gold and silver. This accounts for about 40% to about 95%, and ail values within this range, and more, of the ore over the life of the mine. The ore in this category is typically defined as 1/2 Crushed 'sulfide' or 'transition'

[00151] EXAMPLE 14

[00152] In an embodiment the heap, in a precious métal from ore recovery System, such as the System of Example 10, FIG. 4, processes three different categories of ore.

[00153] Ore Category 1 - low-grade ROM ore (oxide, transition, or both) with high cyanide soluble gold is cyanide leached to extract gold and silver. This accounts for from about 0% to about 10%, and ail values within this range, of the ore over the life of mine. A pre-oxidation step is typically not used for this ore.

[00154] Ore Category 2 - high-grade % Crushed ore (oxide, transition, or both) with high cyanide soluble gold is crushed to a P80 of 3/4 and cyanide leached to extract gold and silver. This accounts for about 0% to about 10%, and ail values within this range, of the ore over the life of mine. A pre-oxidation step is typically not used for this ore.

[00155] Ore Category 3 - low cyanide soluble Crushed (sulfide, transition, or both) ratio ores are crushed to a P80 of 1/2. The crushed ore is mixed with soda ash, trôna or a mixture of both, to induce an alkaline 'pre-oxidation' process. After the oxidation proJess has been completed to the desired extent, the orelwill be 'rinsed' with saturated lime solution and then cyanide leached to extract gold and silver. This accounts for about 5% to about 95%, and more, and ail values within this range, of the ore over the life of the mine.

! ί

[00156] EXAMPLE 15

[00157] To détermine a base line for comparison purposes, direct cyanidation leach of bulk samples of transitional and sulfide ore are conducted. Samples are ground to a P80 of 325 mesh for this testing. Recoveries from Domain Beta ore and Domain Gama ore, are in the mid-20% range for gold and 80% range for silver, while other types of sulfide or transition ore hâve recoveries ranging from 45 to 50% for gold and 55 to 83% for silver. These results can be compared to the pre-oxidation and oxidation results (e.g., as provided in this Spécification), which shows the significant improvement in gold recovery from using this process. And, also an improvement in the silver recovery from using this process.

[00158] A measure of recovery by direct cyanidation is the ratio of cyanide soluble métal to the total assay of the métal, that is, AuCN/AuFA and AgCN/AgFA.

[00159] EXAMPLE 16

[00160] Turning to FIGS 5A and 5B, results of batch oxidation tests using trôna are shown. These tests show that full oxidation is not required to attain high recoveries in subséquent cyanide leaching. About 85% of the gold and 92% of the silver can be recovered by cyanidation if 60% of the sulfide-sulfur content in the concentrate is oxidized

[00161] For some ores, and embodiments, reaction kinetics are improved by higher températures up to 75°C. Higher reaction températures (around 90°C) can resuit in slower oxidation kinetics, (it is theorized, perhaps due to the decreased oxygen solubility in the laboratory bench-scale setting).

[00162] EXAMPLE 17

[00163] Turning to FIG. 6 there is shown a graph of the recovery from a pilot plant oxidation-leach recovery system A continuous oxidation pilot plant is run using the same three sulfide domains used in the batch tests of the other Examples. The tests are conducted on each ore type are run separately in order to détermine any operating différences between them and on a composite that is made up of nkaterial from ail types. The pilot plant tests were run using 600 Ib of trôna per ton of concentrate, at 75°C, 25micron grind size, 20% solids and 48 hours total résidence time. Different material types oxidized at varying rates, with Domain Gama materials oxidizing the fastest followed by i

Domain Delta and then Domain Beta. The Master Composite oxidation rate was comparable to Domain Beta.

[00164] Gold recovery versus sulfide oxidation is: 80% gold recovery achieved at 50% sulfide oxidation for ail material types; and 87% gold recovery achieved at 60% sulfide oxidation for ail material types

[00165] Once the ore concentrâtes (e.g., about 40% solids and the trôna concentration is approximately 20%) are oxidized, gold and silver recoveries are significantly improved over the direct cyanidation recoveries. The results of cyanide leaching of oxidized concentrate are shown on FIG. 6 as recovery of gold and silver during 7 months of plant operation. The graph starts with Domain Delta concentrate and then switches to Domain Beta concentrâtes on month 4. Recovery of gold and silver from Domain Delta concentrate peak at around 85%. Gold recovery from Domain Beta reaches 80 percent while silver recoveries from Domain Beta peaked at 90%. The general shape of the lines roughly follows the degree of oxidation of the concentrate.

[00166] EXAMPLE 18

[00167] Oxidation and cyanide leach tests are conducted in plexiglass cylindrical columns that are 1 ft cliameter and 4 ft high. Ore samples are crushed to 1/2 inch, blended and loaded into the columns.

[00168] Oxidation and leaching are performed in sequence in order to separate cyanide from the carbonate solutions. Contact between cyanide and bicarbonate results in losses in cyanide, thereby increasing the cyanide consumption.

[00169] Oxidation is performed for 60, 90 or 120 days by adding trôna to the ore column and applying just enough solution to the column to keep the ore wet. Only enough solution drains at the bottom of the column to use for conditions measurement. This status is maintained to ensure that the interstices in the ore column are filled with oxygen-supplying air and not flooded with solution. A 50-ml sample is collected each day for pH and sulfate analysis. Oxidation isltracked by the amount of sulfate produced.

[00170] At the end of the oxidation cycle, the column is rinsed to recover sulfate held in the column and to wash down as much carbonate and bicarbonate out of the I column as possible. This is followed by a lime water rinse, which will ensure that any remaining carbonate is precipitated as CaCOa. The column then undergoes a standard cyanide column leach.

[00171] EXAMPLE 18A

[00172] Following the method of Example 18, FIG. 8A shows the elapse time in days vs percentage of oxidation and FIG. 8B shows gold and silver recovery based on leach time for a Domain Alpha sulfide sample. Superimposed on the oxidation curve is the running pH of the solution. The plot shows that oxidation is slow in the beginning because there was not enough alkalinity présent. Once the pH is increased, the oxidation reaction proceeds steadily until the column was rinsed. Once the ore is oxidized, gold and silver leached very quickly, which in this column took about 10 days to be essentially complété.

[00173] EXAMPLE 18B

[00174] Following the method of Example 18, FIG. 9 shows the elapse time in days vs percentage of oxidation and shows gold and silver recover based on leach time for a Domain Delta sulfide sample. Superimposed on the oxidation curve is the running pH of the solution. Once the ore is oxidized, gold and silver leached very quickly, which in this column took about 10 days to be essentially complété.

[00175] Sample of sulfide ore column 43 (FIG. 9) obtained gold and silver recoveries of 70% or better, after oxidation for 60 days and achieving this leach recoveries in less than 10 days. After 10 days the leaching recovery leveled out at about 80%.

[00176] EXAMPLE 18C

[00177] Following the method of Example 18, FIG. 10 shows the elapse time in days vs percentage of oxidation and shows gold and silver recovery based on leach time for a Domain Delta sulfide sample. Superimposed on the oxidation curve is the running pH of the solution. Once the ore is oxidized, gold and silver leached very quickly, which in this column took about 10 days to be essentially complété.

[00178] Sample of sblfide ore columns 44 (FIG. 10) obtained gold and silver recoveries of 70% or better, after oxidation for 60 days and achieving the leach recoveries in less than 10 days.

[00179] EXAMPLE 18D !

[00180] Following the method of Example 18, FIG. 11 shows the elapse time in days vs percentage of oxidation and shows gold and silver recover based on leach time for a Domain Beta sulfide sample. Superimposed on the oxidation curve is the running pH of the solution. Although the Domain Beta sample achieved a lower apparent oxidation, it nevertheless resulted in gold and silver recoveries over 60%.

[00181] EXAMPLE 18E

[00182] Following the method of Example 18, FIG. 12 shows the elapse time in days vs percentage of oxidation and shows gold and silver recovery based on leach time for a Domain Beta sulfide sample. Superimposed on the oxidation curve is the running pH of the solution. Although the Domain Beta sample achieved a lower apparent oxidation, it nevertheless resulted gold and silver recoveries over 60%.

[00183] EXAMPLE 18F

[00184] In embodiments following the method of Example 18, the column oxidation followed by leach tests, in general show that higher oxidation levels can produce better gold and silver recoveries in the subséquent cyanide leach process. Thus, FIG. 13 for Domain Delta and FIG. 14 for Domain Beta ores illustrate the effect of higher oxidation levels.

[00185] EXAMPLE 18G

[00186] In embodiments following the method of Example 18, the column tests on Domain Alpha ores are conducted with lower levels of trôna than in Examples 18A-F. At these lower trôna amounts, the pH lingered at low values for about 80 days before more trôna was added to take the pH up doser to 10, which may hâve resulted in the undesirable formation of jarosites. In spite of that, the maximum recoveries obtained are up to about 60% for both gold and silver.

[00187] EXAMPLE 18H

[00188] Turning to FIG. 15 there is shown the effect of increased oxidation on recovery of gold and silver at lower oxidation levels.

[00189] EXAMPLE 19 I

[00190] Typical cyanide leach operations require the addition of two Chemical agents to produce golld and silver. Embodiments of the présent pre-oxidation and leach process (e.g., oxidation-leach recovery method) is dépendent on the successful i utilization of three reagents. In addition to Sodium cyanide and lime, the proposed process must include a carbonate source. In a testing program, either Trôna or Soda Ash were used as carbonate sources during the pre-oxidation cycle of each test.

[00191] Both Trôna and Soda Ash create dual alkaline Systems in solution that allow carbonate concentrations to reach over 20,000 ppm. In embodiments trôna was used during pre-oxidation to neutralize acid and maintain carbonate concentrations high enough to facilitate oxidation by preserving iron solubility. The relationship between 5 Trôna addition (g) and total alkalinity (ppm) was established in the laboratory such that alkalinity measurements could be converted into trôna concentration by the following équation:

[00192] [Trôna] = Total Alkalinity/602.59

[00193] Where Total Alkalinity' is the measured value in ppm and [Trôna] is the 10 résultant concentration in grams per liter. Data illustrating this relationship can be seen in FIG. 16.

[00194] EXAMPLE 20

[00195] It is theorized that for typical ores and heap operation, Trôna Consumption = %Sulfide * Extent of Oxidation * 3,500. ln an embodiment, the LOM 15 average sulfide-sulfur content is 1.99% and the nominal oxidation target is 45%. According to calculated projections, 26 - 27 Ibs/ton Trôna are required per ton of preoxidized ore; ail data generated in the lab indicates that only 26.5 Ibs/ton Trôna will be utilized. FIG. 17 illustrâtes data relating to trôna consumption vs day of oxidation.

[00196] This figure above shows Trôna consumption tracked for the entirety of 20 a lab column pre-oxidation cycle. Addition is represented by steep jumps from one day to the next, small decreases in 'consumption' over time represent total alkalinity leaving the System as part of regular 50 ml sampling, and the steep decrease in consumption after 60 days of oxidation represents back-calculation of residual Trôna during rinsing.

[00197] As acid is generated by the oxidation reaction, Trôna will be 'consumed'. This consumption occurs when ttU carbonate or bicarbonate of Trôna is converted to bicarbonate or carbon dioxide in order to neutralize the produced acid. Over time carbonate concentrations may need to be replenished, for example, either by the addition of more carbonate containing reagents, or by the addition of a hydroxide source that can convert bicarbonate to carbonate while raising the pH of the solution.

[00198] EXAMPLE 21

[00199] In an embodiment soda ash is used as a source of carbonate instead of trôna, as it can deliver higher carbonate concentrations than trôna and requires less mass to be moved and stored in order to provide the same total alkalinity.

[00200] EXAMPLE 22

[00201] Turning to FIG. 18 there is shown cyanide consumption for preoxidized sulfide ore. Cyanide is only added to the column at the conclusion of the rinse. Sodium cyanide is stabilized by manufacturera through the addition of Sodium hydroxide. A common composition for this reagent is a 30% solution of NaCN which will also contain 3% NaOH. In this embodiment the utilization of sodium cyanide solution to leach pre-oxidized ore is no different than its utilization when leaching ore that has not been pre-treated. Sodium cyanide loss is observed for solution Systems that contain high amounts of bicarbonate; while the mechanism is unclear, at this time, experiments hâve shown the incompatibility of Trôna and Sodium cyanide in solution. As a resuit, it it préférable to hâve process Controls in place to separate carbonate containing solutions from cyanide containing ones.

[00202] EXAMPLE 23

[00203] Turning to FIG. 19 there is shown the lime consumption for an embodiment of the présent two step oxidation leach process. Lime is coupled with Sodium cyanide to form the lixiviant solution that drives métal recovery during cyanidation. Lime acts as a hydroxide source in solution that maintains a high enough solution pH to prevent the loss of cyanide to HCN gassing. Lime offsets any additional acid generated during the leach cycle. In addition to its rôle in the lixiviant solution, saturated lime solution is used as a rinsing agent upon completion of the pre-oxidation c^cle. Lime solution pushes out and dilutes carbonatâ solutions prior to the addition of cyanide to a panel. This lime solution is diverted to the carbonate solution ponds where it will serve to regenerate carbonate concentration from bicarbonate that has built up. The consumption of lime when used for the cyanidation of pre-oxidized ore is lower than when it is used to leach un-pretreated ore. The majority of lime addition/consumption is done during the rinse stage of the process. In embodiments, after cyanidation has commenced, additional lime is rarely used, as the NaOH provided by cyanide solution is able to neutralize residual acid génération and maintain pH.

[00204] EXAMPLE 24

[00205] Turning to FIG. 20 there is shown the consumption of the three primary 5 reagents for an embodiment of the two step oxidation leach process for sulfide ores.

[00206] EXAMPLE 25

[00207] Turning to FIG. 21 there is shown a process flow and water balance for an embodiment of the présent Systems. The acronyms used in the Figure are: FW = fresh water, SW = seal water, PW = process water, BS = barren solution.

[00208] It is noted that there is no requirement to provide or address the theory underlying the novel and groundbreaking processes, materials, performance or other bénéficiai features and properties that are the subject of, or associated with, embodiments of the présent inventions. Nevertheless, various théories are provided in this spécification to further advance the art in this area. The théories put forth in this 15 spécification, and unless expressly stated otherwise, in no way limit, restrict or narrow the scope of protection to be afforded the claimed inventions. These théories many not be required or practiced to utilize the présent inventions. It is further understood that the présent inventions may lead to new, and heretofore unknown théories to explain the function-features of embodiments of the methods, articles, materials, devices and

System of the présent inventions; and such later developed théories shall not limit the scope of protection afforded the présent inventions.

[00209] The various embodiments of Systems, equipment, techniques, methods, activities and operations set forth in this spécification may be used for various other activities and in other fields in addition to those set forth herein. Additionally, 25 these embodiments, for example, may be used with: other eqJipment or activities that may be developed in the future; and with existing equipment or activities which may be modified, in-part, based on the teachings of this spécification. Further, the various embodiments set forth in this spécification may be used with each other in different and various combinations. Thus, for example, the configurations provided in the various 30 embodiments of this spécification may be used with each other; and the scope of protection afforded the présent inventions should not be limited to a particular embodiment, configuration or arrangement that is set forth in a particular embodiment, example, or in an embodiment in a particular Figure.

[00210] The invention may be embodied in other forms than those specifically disclosed herein without departing from its spirit or essential characteristics. The described embodiments are to be considered in ail respects only as illustrative and not restrictive.

In the Claims

Claims (38)

In the Claims

1.8% to 11 %. '

1. A System for the processing and recovery of metals from ores having high sulfide content, the System comprising:

a. a crushing segment comprising: (i) an ore comprising a métal and a sulfide; and, (ii) crushing equipment;

b. an oxidizing pH moderating material handling and distribution segment, the handling and distribution segment comprising an oxidizing pH moderating material and distributing equipment; wherein handling and distribution segment is configured to meter and add the oxidizing pH moderating material to the ore comprising a métal and a sulfide;

c. the crushing segment, the handling and distribution segment, or both, configured to mix and conduct an oxidation reaction; whereby the sulfide is oxidized and thereby creating a pre-oxidized ore;

d. a heap leach segment, comprising the pre-oxidized ore and a reagent for extracting the métal from the pre-oxidized ore, thereby forming a solution comprising the métal; and,

e. a métal recovery segment, whereby the métal is recovered from the solution.

2. The System of claim 1, wherein the System is a surface mine in the earth.

3. The System of claims 1 or 2, wherein the ore comprises a sulfide ore or a transition ore.

4. The System of claim 1, comprising a holding pile of pre-oxidize ore, wherein the oxidation reaction continues in the holding pile.

5. The Systems of claims 1,3, or 4, wherein theiore has a moisture content of from

6. The Systems of claims 1,3, or 4, wherein the ore has a density of 20% to 60%, and ail values within this range.

7. The System of claim 1, wherein the métal recovery segment comprises a zinc cementation System.

8. The Systems of claims 1,3, or 4, wherein the oxidizing pH moderating material comprises trôna or soda ash.

9. The Systems of claims 1,3, or 4, wherein the pre-oxidized ore has a P80 particle size of from 0.23 inches to 1.1 inch.

10 days to 50 days.

10.

10. A System for the processing and recovery of metals from ores having high sulfide content, the System comprising:

a. a crushing segment comprising;

b. an oxidizing pH moderating material handling and distribution segment, the handling and distribution segment comprising an oxidizing pH moderating material and distributing equipment; wherein handling and distribution segment is configured to meter and add the oxidizing pH moderating material to an ore comprising a métal and a sulfide;

c. the oxidizing pH moderating material selected from the group consisting of trôna, soda ash, and a mixture of soda ash and trôna;

d. the crushing segment, the handling and distribution segment, or both, configured to mix and conduct an oxidation reaction;

e. a heap leach segment, comprising a pre-oxidized ore having a particle size of from 0.45 inches to 0.83 inches, and a reagent comprising cyanide, for extracting the métal from the pre-oxidized ore; and,

f. a métal recovery segment.

11 .The System of claim 10, comprising a sulfide ore, the sulfide ore comprising a métal enrichment; and wherein the métal recovery segment comprises at least 60% of the métal from the métal complex in the ore; or at least 70% of the métal from the métal complex in the ore; or at least 80% of the métal from the métal complex in the ore.

12 .The Systems of claims 10 or 11, wherein the métal is selected from the group consisting of gold, silver and cooper. I

13 . A System for the processing and recovery of metals from ores having high sulfide content, the System comprising:

a. a crushing segment comprising: (i) an ore comprising a métal and a sulfide;

and, (ii) crushing equipment;

b. an oxidizing pH moderating material handling and distribution segment, the handling and distribution segment comprising an oxidizing pH moderating material and distributing equipment; wherein handling and distribution segment is configured to meter and add the oxidizing pH moderating material to the ore comprising a métal and a sulfide;

c. the crushing segment, the handling and distribution segment, or both, configured to mix and conduct an oxidation reaction; whereby the sulfide is oxidized and thereby creating a buffered pre-oxidized ore;

d. a heap leach segment, comprising the pre-oxidized ore and a reagent for extracting the métal from the pre-oxidized ore, thereby forming a solution comprising the métal; and,

e. a métal recovery segment, whereby the métal is recovered from the solution.

14 .The system of claim 13, comprising a holding pile of pre-oxidize ore, wherein the oxidation reaction continues in the holding pile.

15 .The system of claim 13, wherein the buffered pre-oxidized ore has a pH of 8 to

16 .The system of claim 13, wherein the pre-oxidized ore has a total alkalinity of 13,500 ppm to 66,000 ppm.

17 . A system for the processing and recovery of metals from sulfide ores, the system comprising:

a. a means for crushing, the means comprising: (i) an ore comprising a métal and a sulfide; and, (ii) a primary and secondary crusher;

b. a means for delivering an oxidizing pH moderating material to the ore, the means comprising an oxidizing pH moderating material selected from the group consisting of trôna, soda ash, and sodium nitrate;

c. a rrieans for mixing the oxidizing pH moderating matériel and ore; and, d. a means for conducting an oxidation reaction; whereby the sulfide is

e.

f.

oxidized and thereby creating a pre-oxidized ore; and, a means for separating and recovering the métal from the pre-oxidized ore; whereby at 70% of the métal is recovered from the ore.

18 . A method for the processing and recovery of metals from ores having high sulfide content, the method comprising:

a. a crushing an ore comprising a water content, a métal and a sulfide;

b. mixing the ore with an oxidizing pH moderating material, and thereby forming a mixture of the ore and the oxidizing pH moderating material;

c. the oxidizing pH moderating material:

i. oxidizing the sulfide for a first time period;

ii. buffering the mixture; whereby the mixture has a pH of 7 to 10 during the first time period;

d. whereby a pre-oxidation ore is formed during the first period of time, the pre-oxidized ore having a percentage of the sulfide oxidized;

e. during a second time period leaching the pre-oxidized ore with a reagent to form a prégnant solution comprising the métal;

f. recovering the métal from the prégnant solution, whereby 60% to 95% of the métal is recovered from the ore.

19 .The method of claim 18, comprising rinsing the pre-oxidized ore after the first period of time.

20 . The method of claim 18, comprising rinsing the pre-oxidized ore before the second period of time.

21 .The method of claim 18, comprising second time period and the first time period do not overlap.

22 .The methods of claims 18, 19, 20 or 21, wherein the first time period is from 30 days to 150 days.

23 .The methods of claims 18, 19, 20 or 21, wherein the second time period is from

24 .The method of claim 18, wherein the first time period is less than 120 days.

25 .The method of clajm 19, wherein the first time period is less than 120 days.

26 .The method of claim 20, wherein the first time period is less than 120 days.

27 .The method of claim 24, wherein the second time period is less than 40 days.

28 .The method of cia m 25, wherein the second time period is less than 40 days.

29 .The method of claim 26, wherein the second time period is less than 40 days.

30 .The method of claim 18, wherein the first time period is less than 120 days; and wherein the percentage of sulfide oxidized is greaterthan 20%.

31 .The method of claim 19, wherein the first time period is less than 120 days; and wherein the percentage of sulfide oxidized is greater than 20%.

32 .The method of claim 20, wherein the first time period is less than 120 days; and wherein the percentage of sulfide oxidized is greater than 20%.

33 .The method of claim 24, wherein the second time period is less than 40 days; and wherein the percentage of sulfide oxidized is greater than 20%.

34 .The method of claim 25, wherein the second time period is less than 40 days; and wherein the percentage of sulfide oxidized is greater than 20%.

35 .The method of claim 26, wherein the second time period is less than 40 days; and wherein the percentage of sulfide oxidized is greater than 20%.

36 .The methods of claims18, 19, 20, 21, 24, 27, 31 and 34, wherein the métal is selected from the group consisting of gold, silver and cooper.

37 .The methods of daims 18, 19, 20, 21,24, 27, 31 and 34, wherein an oxidizing pH moderating material is selected from the group consisting of trôna, soda ash, and sodium nitrate.

38 . A method of recovering a precious métal from an ore comprising: forming an aqueous layer on the surface of a particle of the ore; the aqueous layer comprising an oxidizing pH moderating material, wherein the oxidizing pH moderating material buffers the aqueous layer; the aqueous layer defining a surface expose to air; wherein an oxidation reaction is carried out in the aqueous layer; there after the ore particle is subjected to heap leaching for extraction of the precious métal from the ore.