Method for removing iron from hematite in zinc hydrometallurgy

Abstract

The invention discloses a method for removing iron from hematite in wet-process zinc smelting, and relates to the technical field of wet-process zinc smelting. The method comprises the following steps: (1) carrying out fluidized bed roasting on first zinc sulfide concentrate to obtain roasted sand; (2) the roasted sand is subjected to neutral leaching, and neutral leaching residues are obtained; (3) the neutral leaching residues are subjected to neutral leaching residue acid leaching treatment, and leachate is obtained; (4) preparing a mixture of the leachate and a neutralizer, and carrying out pre-neutralization treatment to obtain a pre-neutralized solution; and (5) the pre-neutralization liquid is subjected to hematite iron removal treatment. Therefore, use of gypsum residues can be avoided, and meanwhile efficient leaching of zinc and effective recovery of iron are achieved.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical zinc smelting technology, and in particular to a method for removing iron from hematite during hydrometallurgical zinc smelting. Background Technology

[0002] In the hydrometallurgical zinc refining process, iron precipitation from the zinc-containing solution is crucial. After roasting and leaching, zinc sulfide concentrate often contains a large amount of iron impurities in the solution. Common methods for iron precipitation in hydrometallurgical zinc refining include the jaundice process, the goethite process, and the hematite process. Among them, the jaundice process can obtain a sulfate solution suitable for electrolysis and has a high recovery rate of valuable metals such as copper and cadmium. However, this method produces a large amount of slag, with high sulfur content and low iron content (the actual slag contains only about 30% Fe). The iron slag obtained by the goethite process contains about 40% Fe, which is higher than that of the jaundice process, but the acid-base balance is difficult to control during the iron precipitation process, and the iron slag contains a relatively high content of valuable metals such as zinc. The hematite process, on the other hand, can not only achieve a high recovery rate of valuable metals, but also produces hematite slag with an iron content as high as 55% and a small amount of slag, which can be sold as an iron-containing material. In related technologies, SO2 pressure leaching is generally used to dissolve zinc and iron in the intermediate leaching slag and reduce iron. However, SO2 is partially converted into sulfuric acid, resulting in an increase in sulfuric acid in the system. To maintain the system's acid balance, lime needs to be added for neutralization to remove excess sulfate ions, resulting in a large amount of gypsum slag. This gypsum slag has a high zinc content and requires separate treatment, leading to high production costs. The patent "Method for Joint Leaching of High-Iron Zinc Sulfide Concentrate and High-Iron Zinc Calcined Sand Leaching Residue" (application number: 2013103080605) discloses a method of mixed leaching of high-iron zinc concentrate and high-iron zinc calcined sand leaching residue. The high-iron zinc sulfide concentrate and high-iron zinc calcined sand leaching residue are mixed at a mass ratio of 0.15:1-0.35:1, the leaching agent is a solution containing 160-190 g / L of sulfuric acid, and 1-3 kg of sodium lignosulfonate is added per ton of zinc concentrate. The leaching liquid-to-solid ratio is 6-8 mL / g, and the reaction temperature is 85-95℃. However, this method requires a large amount of reducing agent, resulting in high production costs. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a method for removing iron from hematite in hydrometallurgical zinc smelting.

[0004] A method for removing iron from hematite in hydrometallurgical zinc smelting according to a first aspect of the present invention includes the following steps: (1) The first zinc sulfide concentrate was subjected to fluidized bed roasting to obtain roasted sand; (2) The calcined sand is subjected to neutral leaching to obtain a medium leaching residue; (3) The intermediate leaching residue is subjected to intermediate leaching residue acid leaching treatment to obtain leachate; (4) Prepare a mixture of the leachate and the neutralizing agent, and perform pre-neutralization treatment to obtain a pre-neutralized solution; (5) The pre-neutralized liquid is subjected to hematite removal treatment.

[0005] The method according to embodiments of the present invention has at least the following beneficial effects: The method in this embodiment achieves efficient zinc leaching and effective iron recovery by sequentially subjecting zinc sulfide concentrate to fluidized bed roasting, neutral leaching, acid leaching of intermediate leaching residue, pre-neutralization treatment, and hematite iron removal treatment. Waste electrolyte is added to the system in two parts (50%-70% for neutral leaching and 30%-50% for acid leaching of intermediate leaching residue). Iron in the intermediate leaching residue is leached into the acid leaching solution. Therefore, the volume of solution used for hematite iron removal is only 30%-50% of the total volume, effectively reducing the volume of the pre-neutralization solution. After hematite iron removal, the iron-removed liquid and hematite slag are cooled, depressurized, and separated into liquid and solid components. The iron-removed liquid is returned to neutral leaching, while the hematite slag (Fe2O3) is sold.

[0006] Oxygen pressure reduction leaching is used to extract the leaching residue, and hot acid leaching is combined with Fe. 3+ The reduction reaction is integrated under low-oxygen, low-temperature, and low-pressure conditions. ZnS in the zinc sulfide concentrate acts as a reducing agent, preventing SO2 reduction from increasing sulfuric acid levels in the system, maintaining acid balance, avoiding subsequent gypsum slag formation, saving production costs, and reducing process and equipment investment. Oxygen oxidizes the active groups in lignin, enhancing its reducing power and reducing the amount of elemental sulfur coating the ZnS surface. The amount of zinc sulfide concentrate used as a reducing agent can be reduced from 1.4 times the traditional theoretical value to 1.2 times, reducing the amount of reducing agent used and improving reduction efficiency. Excess zinc sulfide concentrate also undergoes oxygen pressure leaching, increasing the zinc leaching rate. Therefore, oxygen pressure reduction leaching enhances the reaction process and improves reduction leaching efficiency, achieving a zinc leaching rate of over 96%, while simultaneously leaching over 83% of the iron into the solution, resulting in an iron reduction rate of over 95%.

[0007] According to some embodiments of the present invention, the boiling roasting temperature is 870℃-970℃. For example, it can be 870℃, 875℃, 880℃, 885℃, 890℃, 895℃, 900℃, 905℃, 910℃, 915℃, 920℃, 925℃, 930℃, 935℃, 940℃, 945℃, 950℃, 955℃, 960℃, 965℃, or 970℃.

[0008] According to some embodiments of the present invention, the intermediate leaching temperature of the neutral leaching is 60°C-70°C. For example, it can be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, or 70°C.

[0009] According to some embodiments of the present invention, the intermediate immersion time for the neutral leaching is 1 h to 2 h. For example, it can be 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h or 2 h.

[0010] According to some embodiments of the present invention, the endpoint pH of the neutral leaching is 4.8-5.4. For example, it can be 4.8, 4.9, 5, 5.1, 5.2, 5.3 or 5.4.

[0011] According to some embodiments of the present invention, the intermediate leaching treatment includes: preparing a mixture of the calcined sand and a second solution containing sulfuric acid, and performing the intermediate leaching treatment. The second solution includes at least one of the following: waste electrolyte (from the zinc electrowinning process), the iron-removed liquid obtained in step (5), and the production wash water.

[0012] According to some embodiments of the present invention, the sulfuric acid content of the second solution is 30 g / L-75 g / L. For example, it can be 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, or 70 g / L.

[0013] According to some embodiments of the present invention, the mass-to-volume ratio of the calcined ore to the second solution is 1 g: (6-10) mL. For example, it can be 1 g: 6 mL, 1 g: 6.5 mL, 1 g: 7 mL, 1 g: 7.5 mL, 1 g: 8 mL, 1 g: 8.5 mL, 1 g: 9 mL, 1 g: 9.5 mL, or 1 g: 10 mL.

[0014] According to some embodiments of the present invention, the first solution includes, but is not limited to, waste electrolyte. The waste electrolyte in the first solution accounts for 30%-50% (V / V)% of the total volume of waste electrolyte in the first solution and waste electrolyte in the second solution. For example, it can be 30% (V / V)%, 31% (V / V)%, 32% (V / V)%, 33% (V / V)%, 34% (V / V)%, 35% (V / V)%, 36% (V / V)%, 37% (V / V)%, 38% (V / V)%, 39% (V / V)%, 40% (V / V)%, 41% (V / V)%, 42% (V / V)%, 43% (V / V)%, 44% (V / V)%, 45% (V / V)%, 46% (V / V)%, 47% (V / V)%, 48% (V / V)%, 49% (V / V)%, or 50% (V / V)%.

[0015] According to some embodiments of the present invention, the intermediate leaching residue acid leaching treatment includes: A mixture of the intermediate leaching residue, a first solution containing sulfuric acid, a second zinc sulfide concentrate, and a surfactant is prepared and subjected to oxygen pressure reduction leaching. Alternatively, a mixture of the intermediate leaching residue and a first solution containing sulfuric acid is prepared and subjected to hot acid leaching to obtain a hot acid leachate; a mixture of the hot acid leachate, a second zinc sulfide concentrate, and a surfactant is prepared and subjected to oxygen pressure reduction leaching.

[0016] According to some embodiments of the present invention, the acid content of the first solution is 140 g / L-190 g / L. The first solution includes, but is not limited to, waste electrolyte. For example, it can be 140 g / L, 145 g / L, 150 g / L, 155 g / L, 160 g / L, 165 g / L, 170 g / L, 175 g / L, 180 g / L, 185 g / L, or 190 g / L.

[0017] According to some embodiments of the present invention, the temperature of the hot acid leaching is 85℃-95℃. For example, it can be 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃ or 95℃.

[0018] According to some embodiments of the present invention, the hot acid leaching time is 2 h-3 h. For example, it can be 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h or 3 h.

[0019] According to some embodiments of the present invention, the final acid content of the hot acid leaching is 40 g / L-60 g / L. For example, it can be 40 g / L, 41 g / L, 42 g / L, 43 g / L, 44 g / L, 45 g / L, 46 g / L, 47 g / L, 48 g / L, 49 g / L, 50 g / L, 51 g / L, 52 g / L, 53 g / L, 54 g / L, 55 g / L, 56 g / L, 57 g / L, 58 g / L, 59 g / L, or 60 g / L.

[0020] According to some embodiments of the present invention, the liquid-to-solid ratio of the hot acid leaching is (4-6) mL: 1 g. For example, it can be 4 mL: 1 g, 4.2 mL: 1 g, 4.4 mL: 1 g, 4.6 mL: 1 g, 4.8 mL: 1 g, 5 mL: 1 g, 5.2 mL: 1 g, 5.4 mL: 1 g, 5.6 mL: 1 g, 5.8 mL: 1 g, or 6 mL: 1 g.

[0021] According to some embodiments of the present invention, the second zinc sulfide concentrate accounts for 15%-20% of the total mass of the first and second zinc sulfide concentrates. By controlling the ratio of the first and second zinc sulfide concentrates, most of the ZnS acts as a reducing agent during the oxygen pressure reduction leaching process, avoiding the increase of sulfuric acid in the system due to SO2 reduction, maintaining the acid balance of the system, avoiding the subsequent generation of gypsum slag, and saving production costs.

[0022] According to some embodiments of the present invention, the surfactant includes at least one of sodium lignosulfonate and calcium lignosulfonate.

[0023] According to some embodiments of the present invention, the mass ratio of the second zinc sulfide concentrate to the surfactant is 100:(0.3-0.5). For example, it can be 100:0.3, 100:0.31, 100:0.32, 100:0.33, 100:0.34, 100:0.35, 100:0.36, 100:0.37, 100:0.38, 100:0.39, 100:0.4, 100:0.41, 100:0.42, 100:0.43, 100:0.44, 100:0.45, 100:0.46, 100:0.47, 100:0.48, 100:0.49, or 100:0.5.

[0024] According to some embodiments of the present invention, the temperature of the oxygen pressure reduction leaching is 110℃-120℃. For example, it can be 110℃, 111℃, 112℃, 113℃, 114℃, 115℃, 116℃, 117℃, 118℃, 119℃ or 120℃.

[0025] According to some embodiments of the present invention, the oxygen pressure reduction leaching time is 1.5 h to 2.5 h. For example, it can be 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h or 2.5 h.

[0026] According to some embodiments of the present invention, the pressure of the oxygen pressure reduction leaching is 0.3 MPa-0.4 MPa. For example, it can be 0.3 MPa, 0.31 MPa, 0.32 MPa, 0.33 MPa, 0.34 MPa, 0.35 MPa, 0.36 MPa, 0.37 MPa, 0.38 MPa, 0.39 MPa or 0.40 MPa.

[0027] According to some embodiments of the present invention, the final acid content of the oxygen pressure reduction leaching is 30 g / L-40 g / L. For example, it can be 30 g / L, 31 g / L, 32 g / L, 33 g / L, 34 g / L, 35 g / L, 36 g / L, 37 g / L, 38 g / L, 39 g / L, or 40 g / L.

[0028] According to some embodiments of the present invention, if the acid leaching treatment of the intermediate leaching residue includes: preparing a mixture of the intermediate leaching residue with a first solution containing sulfuric acid, a second zinc sulfide concentrate, and a surfactant, and performing oxygen pressure reduction leaching; the liquid-to-solid ratio of the mixture is (4-6) mL: 1 g. For example, it can be 4 mL: 1 g, 4.2 mL: 1 g, 4.4 mL: 1 g, 4.6 mL: 1 g, 4.8 mL: 1 g, 5 mL: 1 g, 5.2 mL: 1 g, 5.4 mL: 1 g, 5.6 mL: 1 g, 5.8 mL: 1 g, or 6 mL: 1 g.

[0029] According to some embodiments of the present invention, the temperature of the pre-neutralization treatment in (4) is 55°C-65°C. For example, it can be 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C or 65°C.

[0030] According to some embodiments of the present invention, the pre-neutralization process described in (4) takes 0.5 h to 1 h. For example, it can be 0.5 h, 0.55 h, 0.6 h, 0.65 h, 0.7 h, 0.75 h, 0.8 h, 0.85 h, 0.9 h, 0.95 h or 1 h.

[0031] According to some embodiments of the present invention, the final pH of the pre-neutralization treatment described in (4) is 1.5-4.5. For example, it can be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4 or 4.5.

[0032] According to some embodiments of the present invention, in (4), the neutralizing agent includes calcined sand and / or zinc oxide.

[0033] According to some embodiments of the present invention, the iron removal treatment of hematite in (5) includes the following steps: In an oxygen-rich steam atmosphere, the pre-neutralized liquid is reacted at 180℃-200℃ and a total pressure of 1.6 MPa-2.0 MPa for 3-5 hours. For example, the temperature can be 180℃, 181℃, 182℃, 183℃, 184℃, 185℃, 186℃, 187℃, 188℃, 189℃, 190℃, 191℃, 192℃, 193℃, 194℃, 195℃, 196℃, 197℃, 198℃, 199℃, or 200℃; the total pressure can be 1.6 MPa, 1.65 MPa, 1.7 MPa, 1.75 MPa, 1.8 MPa, 1.85 MPa, 1.9 MPa, 1.95 MPa, or 2 MPa; the reaction time can be 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h, or 5 h.

[0034] According to some embodiments of the present invention, the oxygen partial pressure in the oxygen-enriched steam atmosphere of the hematite removal treatment is 0.4 MPa-0.8 MPa. For example, it can be 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa or 0.8 MPa.

[0035] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0036] Figure 1 This is a reaction flow diagram of the method for removing iron from hematite in hydrometallurgical zinc smelting according to Examples 1-3 of the present invention; Figure 2 This is a reaction flow diagram of the method for removing iron from hematite in hydrometallurgical zinc smelting according to Examples 4-6 of the present invention. Detailed Implementation

[0037] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0038] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0039] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0040] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0041] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0042] In the method for removing iron from hematite in the hydrometallurgical zinc smelting of the present invention, the zinc sulfide concentrate is sequentially subjected to fluidized bed roasting, neutral leaching treatment, acid leaching treatment of intermediate leaching residue, pre-neutralization, and hematite iron removal, thereby achieving the separation of iron and zinc in the zinc sulfide concentrate. The reaction principles of the two key reaction steps are as follows: (1) During the reduction leaching process, zinc sulfide concentrate generates zinc sulfate and elemental sulfur under oxygen pressure conditions, as shown in Formula 1; zinc ferrite (ZnO·Fe2O3) in the intermediate leaching residue dissolves to generate zinc sulfate and ferric sulfate under high temperature and high acid conditions, as shown in Formula 2. Adding an appropriate amount of zinc sulfide concentrate reducing agent (mainly ZnS) to the hot acid leaching solution reduces ferric sulfate to ferrous sulfate, as shown in Formula 3, thereby achieving the purpose of zinc ferrite leaching and iron reduction.

[0043] ZnS + H₂SO₄ + 0.5O₂ = ZnSO₄ + S 0 +H2O (Formula 1); ZnO·Fe2O3+4H2SO4=ZnSO4+Fe2(SO4)3+4H2O (Formula 2); ZnS + Fe2(SO4)3 = ZnSO4 + 2FeSO4 + S 0 (Equation 3).

[0044] Depending on the lead and silver content in the zinc concentrate raw material, the two steps of hot acid leaching of the intermediate leaching residue and reduction of the hot acid leaching solution can be combined into a single process. This yields a hot acid leaching residue enriched with lead and silver, which can then be sent to a pyrometallurgical slag treatment facility for the recovery of valuable metals such as lead and silver.

[0045] During the reduction leaching process, the addition of lignin can reduce the encapsulation of zinc concentrate by the generated elemental sulfur and improve the activity of zinc concentrate; the introduction of oxygen can oxidize the active groups in lignin and enhance its reducing power, thereby reducing the amount of reducing agent used and improving the reduction efficiency.

[0046] (2) During the iron removal process of hematite, oxygen is introduced slowly at 180℃-200℃ and 1.6-2.0 MPa to remove Fe from the pre-neutralized solution. 2+ Oxidized to Fe 3+ The reaction is as shown in Equation 4. Among them, the Fe in the leachate... 3+ It will hydrolyze to form a reddish-brown Fe2O3 precipitate, as shown in Formula 5.

[0047] 4FeSO4 + O2 + 2H2SO4 = 2Fe2(SO4)3 + 2H2O (Equation 4); Fe2(SO4)3+3H2O=Fe2O3+3H2SO4 (Formula 5).

[0048] The waste electrolyte used in the embodiments and comparative examples of this disclosure all comes from the zinc electrowinning process. Production wash water comes from various stages of production.

[0049] Unless otherwise specified, "final acid" and "acid content" in this disclosure refer to sulfuric acid concentration.

[0050] Example 1 This example provides a method for removing iron from hematite in hydrometallurgical zinc smelting, the reaction process is as follows: Figure 1 As shown. The steps are as follows: (1) Fluidized bed roasting: 8.2 t / h of zinc sulfide concentrate (containing 49 wt% Zn, 10 wt% Fe, and 31 wt% S) was fed into a fluidized bed roasting furnace for roasting and acid production. The roasting temperature was set at 930℃, and 7.3 t / h of roasted sand was produced. (2) Neutral leaching: Neutral leaching is carried out on the calcined sand with waste electrolyte containing sulfuric acid, iron removal liquid and production wash water. The solid-liquid ratio of the leaching solution is controlled at 9 mL: 1 g, the leaching temperature is 70℃, the leaching time is 2 h, and the final pH is 5.0. The products are leaching residue and leaching solution. The leaching solution is sent to purification, electrolysis and casting to produce electrolytic zinc.

[0051] (3) Acid leaching treatment of intermediate leaching residue (oxygen pressure reduction leaching): 3.2 t / h of intermediate leaching residue and 1.8 t / h of zinc sulfide concentrate were mixed with sodium lignosulfonate (mass ratio of zinc sulfide concentrate to sodium lignosulfonate was 100:0.35) and waste electrolyte (sulfuric acid concentration 152 g / L), added to a high-pressure reactor, and oxygen (O2 content 99 vol%) was introduced for oxygen pressure reduction leaching. The liquid-to-solid ratio was 6 mL:1 g, the leaching temperature was controlled at 115℃, the total pressure at 0.35 MPa, the leaching time at 2.0 h, and the final acid concentration at 40 g / L. The resulting leaching residue was 2.3 t / h (Zn 4.6 wt%, Fe 6.5 wt%, S 24.3 wt%) and leachate. The zinc leaching rate was 97.84%, and the iron leaching rate was 85.05%. The leaching residue was sent for pyrometallurgical slag treatment.

[0052] (4) Pre-neutralization treatment: Add calcined sand to the leachate for pre-neutralization, control the temperature at 65℃ for 1 h, and the final pH is 2.0. The products are pre-neutralized residue and pre-neutralized liquid.

[0053] (5) Iron removal treatment of hematite: Add the pre-neutralization liquid to the autoclave and introduce oxygen (O2 content 99 vol%, 300 Nm³). 3 The iron removal reaction was carried out using steam at a controlled temperature of 190℃, a total pressure of 1.8 MPa (oxygen partial pressure 0.5 MPa), and a time of 4.5 h, producing 1.37 t / h of hematite slag (Zn 1.5wt%, Fe 56wt%, S 5wt%) and iron removal liquid. The iron removal liquid was returned to neutral leaching.

[0054] Example 2 This example provides a method for removing iron from hematite in hydrometallurgical zinc smelting, the reaction process is as follows: Figure 1 As shown. The steps are as follows: (1) Fluidized bed roasting: 8.4 t / h of zinc sulfide concentrate (containing 50 wt% Zn, 9 wt% Fe, and 30 wt% S) was fed into a fluidized bed roasting furnace for roasting and acid production. The roasting temperature was set at 920℃, and 7.4 t / h of roasted sand was produced. (2) Neutral leaching: Neutral leaching is carried out on the calcined sand with waste electrolyte containing sulfuric acid, iron removal liquid and production wash water. The solid-liquid ratio of the leaching solution is controlled at 7.5 mL: 1 g, the leaching temperature is 65℃, the leaching time is 1.5 h, and the final pH is 4.8. The products are leaching residue and leaching solution. The leaching solution is sent to purification, electrolysis and casting to produce electrolytic zinc.

[0055] (3) Acid leaching treatment of intermediate leaching residue (oxygen pressure reduction leaching): 3.3 t / h and 1.6 t / h of intermediate leaching residue and zinc sulfide concentrate were mixed with sodium lignosulfonate (mass ratio of zinc sulfide concentrate to sodium lignosulfonate was 100:0.4) and waste electrolyte (sulfuric acid concentration 167 g / L), added to a high-pressure reactor, and oxygen (O2 content 99 vol%) was introduced for oxygen pressure reduction leaching. The liquid-to-solid ratio was 5 mL:1 g, the leaching temperature was controlled at 115℃, the total pressure at 0.35 MPa, the leaching time at 1.8 h, and the final acid concentration at 35 g / L. The resulting leaching residue was 2.2 t / h (Zn 4.7 wt%, Fe 6.1 wt%, S 21.8 wt%) and leachate. The zinc leaching rate was 97.93%, and the iron leaching rate was 85.09%. The leaching residue was sent for pyrometallurgical slag treatment.

[0056] (4) Pre-neutralization treatment: Add calcined sand to the leachate for pre-neutralization, control the temperature at 60℃, the time at 0.8h, and the final pH at 2.0. The products are pre-neutralized residue and pre-neutralized liquid.

[0057] (5) Iron removal treatment of hematite: Add the pre-neutralization liquid to the autoclave and introduce oxygen (O2 content 99 vol%, 280 Nm). 3 The iron removal reaction was carried out using steam at a controlled temperature of 185℃, a total pressure of 1.7 MPa (oxygen partial pressure 0.6 MPa), and a time of 4.0 h, producing 1.25 t / h of hematite slag (Zn 1.3wt%, Fe 55wt%, S 5wt%) and iron removal solution. The iron removal solution was returned to neutral leaching.

[0058] Example 3 This example provides a method for removing iron from hematite in hydrometallurgical zinc smelting, the reaction process is as follows: Figure 1 As shown. The steps are as follows: (1) Fluidized bed roasting: 8.5 t / h of zinc sulfide concentrate (containing 51 wt% Zn, 8 wt% Fe, and 29 wt% S) is fed into a fluidized bed roasting furnace for roasting and acid production. The roasting temperature is set at 900℃, and 7.5 t / h of roasted sand is produced. (2) Neutral leaching: Neutral leaching is carried out on the calcined sand with waste electrolyte containing sulfuric acid, iron removal liquid and production wash water. The solid-liquid ratio of the leaching solution is controlled at 6 mL: 1 g, the leaching temperature is 60℃, the leaching time is 1.5 h, and the final pH is 4.8. The products are leaching residue and leaching solution. The leaching solution is sent to purification, electrolysis and casting to produce electrolytic zinc.

[0059] (3) Acid leaching treatment of intermediate leaching residue (oxygen pressure reduction leaching): 3.5 t / h of intermediate leaching residue and 1.5 t / h of zinc sulfide concentrate were mixed with sodium lignosulfonate (mass ratio of zinc sulfide concentrate to sodium lignosulfonate was 100:0.45) and waste electrolyte (sulfuric acid concentration 185 g / L), added to a high-pressure reactor, and oxygen (O2 content 99 vol%) was introduced for oxygen pressure reduction leaching. The liquid-to-solid ratio was 4 mL:1 g, the leaching temperature was controlled at 110℃, the total pressure at 0.3 MPa, the leaching time at 1.8 h, and the final acid concentration at 35 g / L. The resulting leaching residue was 2.2 t / h (Zn 4.7 wt%, Fe 5.4 wt%, S 19.8 wt%) and leachate. The zinc leaching rate was 97.97%, and the iron leaching rate was 85.15%. The leaching residue was sent for pyrometallurgical slag treatment.

[0060] (4) Pre-neutralization treatment: Add calcined sand to the leachate for pre-neutralization, control the temperature at 60℃, the time at 0.8h, and the final pH at 2.0. The products are pre-neutralized residue and pre-neutralized liquid.

[0061] (5) Iron removal treatment of hematite: Add the pre-neutralization liquid to the autoclave and introduce oxygen (O2 content 99 vol%, 260 Nm). 3 The iron removal reaction was carried out using steam at a controlled temperature of 185℃, a total pressure of 1.7 MPa (oxygen partial pressure 0.6 MPa), and a time of 4.0 h, producing 1.11 t / h of hematite slag (Zn 1.2wt%, Fe 55wt%, S 4wt%) and iron removal liquid. The iron removal liquid was returned to neutral leaching.

[0062] Example 4 This example provides a method for removing iron from hematite in hydrometallurgical zinc smelting, the reaction process is as follows: Figure 2 As shown. The steps are as follows: (1) Fluidized bed roasting: 8.2 t / h of zinc sulfide concentrate (containing 49 wt% Zn, 10 wt% Fe, and 31 wt% S) was fed into a fluidized bed roasting furnace for roasting and acid production. The roasting temperature was set at 930℃, and 7.3 t / h of roasted sand was produced. (2) Neutral leaching: Neutral leaching is carried out on the calcined sand with waste electrolyte containing sulfuric acid, iron removal liquid and production wash water. The solid-liquid ratio of the leaching solution is controlled at 8 mL: 1 g, the leaching temperature is 70℃, the leaching time is 2 h, and the final pH is 5.0. The products are leaching residue and leaching solution. The leaching solution is sent to purification, electrolysis and casting to produce electrolytic zinc.

[0063] (3) Acid leaching treatment of intermediate leaching residue: (3.1) Hot acid leaching: Waste electrolyte (sulfuric acid concentration 155 g / L) was added to 3.3 t / h of the intermediate leaching residue for hot acid leaching. The liquid-to-solid ratio was 6 mL: 1 g, the leaching temperature was 95°C, the leaching time was 3 h, the final acid concentration was 60 g / L, and 1.64 t / h of hot acid leaching solution and hot acid leaching residue were produced (Zn 4.7 wt%, Fe 8.3 wt%, S 6.1 wt%). The zinc leaching rate was 98.08%, and the iron leaching rate was 83.40%. The hot acid leaching residue was sent to pyrometallurgical slag treatment. (3.2) Oxygen-pressure reduction leaching: Hot acid leaching solution and 1.8 t / h of zinc sulfide concentrate were added to a high-pressure autoclave with sodium lignosulfonate (mass ratio of zinc sulfide concentrate to sodium lignosulfonate 100:0.35). Oxygen was introduced for reduction leaching, controlling the leaching temperature at 115℃, the total pressure at 0.35 MPa, the leaching time at 2.0 h, and the final acid concentration at 40 g / L. The resulting products were leaching residue and leaching solution. The leaching residue was returned to fluidized bed roasting.

[0064] (4) Pre-neutralization treatment: Add calcined sand to the leachate for pre-neutralization, control the temperature at 65℃ for 1 h, and the final pH is 2.0. The products are pre-neutralized residue and pre-neutralized liquid.

[0065] (5) Iron removal treatment of hematite: The pre-neutralized liquid was added to a high-pressure reactor, and oxygen and steam were introduced to carry out the iron precipitation reaction. The reaction temperature was controlled at 190℃, the total pressure at 1.8 MPa (oxygen partial pressure at 0.5 MPa), and the time was 4.5 h. The product was 1.36 t / h of hematite slag (Zn 1.4wt%, Fe 55wt%, S 4.5wt%) and iron removal liquid. The iron removal liquid was returned to neutral leaching.

[0066] Example 5 This example provides a method for removing iron from hematite in a hydrometallurgical zinc smelting process, the reaction flow of which is as follows: Figure 2 As shown. The steps are as follows: (1) Fluidized bed roasting: 8.4 t / h of zinc sulfide concentrate (containing 50wt% Zn, 9wt% Fe, and 30wt% S) was fed into a fluidized bed roasting furnace for roasting and acid production. The roasting temperature was set at 920℃, and 7.4 t / h of roasted sand was produced. (2) Neutral leaching: Neutral leaching is carried out on the calcined sand with waste electrolyte containing sulfuric acid, iron removal liquid and production wash water. The solid-liquid ratio of the leaching solution is controlled at 7 mL: 1 g, the leaching temperature is 65℃, the leaching time is 1.5 h, and the final pH is 4.8. The products are leaching residue and leaching solution. The leaching solution is sent to purification, electrolysis and casting to produce electrolytic zinc.

[0067] (3) Acid leaching treatment of intermediate leaching residue: (3.1) Hot acid leaching: Waste electrolyte was added to the intermediate leaching residue at a rate of 3.3 t / h for hot acid leaching (sulfuric acid concentration 168 g / L), with a liquid-to-solid ratio of 5 mL: 1 g, a leaching temperature of 90°C, a leaching time of 2.5 h, and a final acid concentration of 50 g / L. The resulting hot acid leaching solution and hot acid leaching residue were 1.68 t / h (Zn 4.8 wt%, Fe 7.3 wt%, S 5.3 wt%). The zinc leaching rate was 98.08%, and the iron leaching rate was 83.78%. The hot acid leaching residue was sent to pyrometallurgical slag treatment. (3.2) Oxygen-pressure reduction leaching: Hot acid leaching solution and 1.6 t / h of zinc sulfide concentrate were mixed with sodium lignosulfonate (mass ratio of zinc sulfide concentrate to sodium lignosulfonate was 100:0.4), added to a high-pressure reactor, and oxygen was introduced for reduction leaching. The leaching temperature was controlled at 115℃, the total pressure at 0.35 MPa, the leaching time at 1.8 h, and the final acid concentration at 35 g / L. Leaching residue and leaching solution were obtained. The leaching residue was returned to fluidized bed roasting.

[0068] (4) Pre-neutralization treatment: Add calcined sand to the leachate for pre-neutralization, control the temperature at 60℃, the time at 0.8h, and the final pH at 2.0. The products are pre-neutralized residue and pre-neutralized liquid.

[0069] (5) Iron removal treatment of hematite: The pre-neutralized liquid was added to a high-pressure reactor, and oxygen and steam were introduced to carry out the iron precipitation reaction. The reaction temperature was controlled at 185℃, the total pressure at 1.7 MPa (oxygen partial pressure at 0.6 MPa), and the time was 4.0 h. The product was 1.24 t / h of hematite slag (Zn 1.3%, Fe 54%, S 5.5%) and the iron removal liquid. The iron removal liquid was returned to neutral leaching.

[0070] Example 6 This example provides a method for removing iron from hematite in hydrometallurgical zinc smelting, the reaction process is as follows: Figure 2 As shown. The steps are as follows: (1) Fluidized bed roasting: 8.5 t / h of zinc sulfide concentrate (containing 51wt% Zn, 8wt% Fe, and 29wt% S) is fed into a fluidized bed roasting furnace for roasting and acid production. The roasting temperature is set at 900℃, and 7.5 t / h of roasted sand is produced. (2) Neutral leaching: Neutral leaching is carried out on the calcined sand with waste electrolyte containing sulfuric acid, iron removal liquid and production wash water. The solid-liquid ratio of the leaching solution is controlled at 6 mL: 1 g, the leaching temperature is 60℃, the leaching time is 1.5 h, and the final pH is 4.8. The products are leaching residue and leaching solution. The leaching solution is sent to purification, electrolysis and casting to produce electrolytic zinc.

[0071] (3) Acid leaching treatment of intermediate leaching residue: (3.1) Hot acid leaching: Waste electrolyte (sulfuric acid concentration 188 g / L) was added to 3.5 t / h of intermediate leaching residue for hot acid leaching. The liquid-to-solid ratio was 4 mL: 1 g, the leaching temperature was 85°C, the leaching time was 2 h, the final acid concentration was 40 g / L, and 1.70 t / h of hot acid leaching solution and hot acid leaching residue were produced (Zn 4.8 wt%, Fe 6.4 wt%, S 4.9 wt%). The zinc leaching rate was 98.12% and the iron leaching rate was 84.00%. The hot acid leaching residue was sent to pyrometallurgical slag treatment. (3.2) Oxygen-pressure reduction leaching: Hot acid leaching solution and 1.5 t / h of zinc sulfide concentrate were mixed with sodium lignosulfonate (mass ratio of zinc sulfide concentrate to sodium lignosulfonate was 100:0.45) and added to a high-pressure reactor. Oxygen was introduced for reduction leaching, controlling the leaching temperature at 110℃, the total pressure at 0.3 MPa, the leaching time at 1.8 h, and the final acid concentration at 35 g / L. The resulting products were leaching residue and leaching solution. The leaching residue was returned to fluidized bed roasting.

[0072] (4) Pre-neutralization treatment: Add calcined sand to the leachate for pre-neutralization, control the temperature at 60℃, the time at 0.8h, and the final pH at 2.0. The products are pre-neutralized residue and pre-neutralized liquid.

[0073] (5) Iron removal treatment of hematite: The pre-neutralized liquid was added to the autoclave, and oxygen and steam were introduced to carry out the iron precipitation reaction. The reaction temperature was controlled at 185℃, the total pressure at 1.7 MPa (oxygen partial pressure at 0.6 MPa), and the time was 4.0 h. The product was 1.10 t / h of hematite slag (Zn 1.2%, Fe 55%, S 4%) and iron removal liquid. The iron removal liquid was returned to neutral leaching.

[0074] Comparative Example 1 This example provides a method for removing iron from hematite in wet zinc smelting, which is basically the same as that in Example 1, except that oxygen is not introduced in step (3).

[0075] After treatment, the yield of hematite slag in step (5) decreased by 10 wt%. This may be because lignin, without oxygen catalysis, cannot effectively destroy the surface film formed by elemental sulfur encapsulating ZnS, resulting in a decrease in iron reduction rate.

[0076] Comparative Example 2 This example provides a method for removing iron from hematite in wet zinc smelting, which is basically the same as that in Example 1, except that lignin is not added in step (3).

[0077] After treatment, the yield of hematite slag in step (5) decreased by 15 wt%. This may be because the lack of lignin caused elemental sulfur to encapsulate ZnS, making it difficult for the reduction reaction to continue.

[0078] Comparative Example 3 This example provides a method for removing iron from hematite in wet zinc smelting, which is basically the same as that in Example 1, except that oxygen is not introduced in step (3) and lignin is not added.

[0079] After processing, the yield of hematite slag in step (5) decreased by 12 wt%. This may be because elemental sulfur encapsulates ZnS, resulting in insufficient addition of zinc sulfide concentrate as a reducing agent, which did not reach 1.4 times the traditional theoretical amount, thus leading to a decrease in iron reduction rate.

[0080] Comparative Example 4 This example provides a method for removing iron from hematite in wet zinc smelting, which is basically the same as that in Example 4, except that oxygen is not introduced in step (3).

[0081] After treatment, the yield of hematite slag in step (5) decreased by 8 wt%. This may be because lignin, without oxygen catalysis, cannot effectively break down the surface film formed by elemental sulfur encapsulating ZnS, resulting in a decrease in iron reduction rate.

[0082] Comparative Example 5 This example provides a method for removing iron from hematite in wet zinc smelting, which is basically the same as that in Example 4, except that lignin is not added in step (3).

[0083] After treatment, the yield of hematite slag in step (5) decreased by 12 wt%. This may be because the lack of lignin caused elemental sulfur to encapsulate ZnS, making it difficult for the reduction reaction to continue.

[0084] Comparative Example 6 This example provides a method for removing iron from hematite in wet zinc smelting, which is basically the same as that in Example 4, except that oxygen is not introduced in step (3) and lignin is not added.

[0085] After processing, the yield of hematite slag in step (5) decreased by 10 wt%. This may be because elemental sulfur encapsulates ZnS, resulting in insufficient addition of zinc sulfide concentrate as a reducing agent, which did not reach 1.4 times the traditional theoretical amount, thus leading to a decrease in iron reduction rate.

[0086] The embodiments of the present invention have been described in detail above with reference to the examples. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method of removing iron from hematite in a zinc hydrometallurgical process, c h a r a c t e r i s e d in that, The method comprises the following steps: (1) preparing calcine by boiling roasting first zinc sulfide concentrate; (2) performing neutral leaching on the calcine to obtain neutral leaching residue; (3) performing neutral leaching residue acid leaching treatment on the neutral leaching residue to obtain leaching solution; (4) preparing a mixture of the leaching solution and a neutralizing agent, performing pre-neutralization treatment to obtain pre-neutralization liquid; (5) performing hematite iron removal treatment on the pre-neutralization liquid.

2. The method of claim 1, wherein, The neutral leaching has a neutral leaching temperature of 60-70 DEG C; and / or, a neutral leaching time of 1-2 h; and / or, a terminal pH of 4.8-5.

4.

3. The method of claim 1, wherein, The neutral leaching residue acid leaching treatment comprises: preparing a mixture of the neutral leaching residue, a first solution containing sulfuric acid, second zinc sulfide concentrate and surfactant, and performing oxygen pressure reduction leaching; or, preparing a mixture of the neutral leaching residue and a first solution containing sulfuric acid, and performing hot acid leaching to obtain hot acid leaching solution; preparing a mixture of the hot acid leaching solution, second zinc sulfide concentrate and surfactant, and performing oxygen pressure reduction leaching.

4. The method of claim 3, wherein, The hot acid leaching has a liquid-solid ratio of (4-6) mL: 1 g; and / or, a temperature of 85-95 DEG C; and / or, a time of 2-3 h; and / or, a terminal acid content of 40-60 g / L.

5. The method of claim 3, wherein, The second zinc sulfide concentrate accounts for 15-20% of the total mass of the first zinc sulfide concentrate and the second zinc sulfide concentrate; and / or, the mass ratio of the second zinc sulfide concentrate to the surfactant is 100: (0.3-0.5).

6. The method of claim 3, wherein, The oxygen pressure reduction leaching has a temperature of 110-120 DEG C; and / or, a time of 1.5-2.5 h; and / or, a pressure of 0.3-0.4 MPa; and / or, a terminal acid content of 30-40 g / L.

7. The method of claim 1, wherein, The pre-neutralization treatment in (4) has a temperature of 55-65 DEG C; and / or, a time of 0.5-1 h; and / or, a terminal pH of 1.5-4.

5.

8. The method of claim 1, wherein, The hematite iron removal treatment in (5) comprises the following steps: under an oxygen-rich steam atmosphere, the pre-neutralization liquid is reacted at 180-200 DEG C and a total pressure of 1.6-2.0 MPa for 3-5 h.

9. The method of claim 8, wherein, The oxygen partial pressure in the oxygen-rich steam atmosphere of the hematite iron removal treatment is 0.4-0.8 MPa.

10. The method of claim 1, wherein, The roasting temperature of the boiling roasting in (1) is 870-970 DEG C.

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