Hematite-based iron removal method for iron-containing sulfate solution

Abstract

Disclosed is a hematite-based iron removal method for an iron-containing sulfate solution, comprising the following steps: providing an iron removal device, wherein the iron removal device comprises N vertical reaction vessels (2) and one horizontal reaction vessel (3), discharge ports of the N vertical reaction vessels (2) are connected in parallel to a feed port of the horizontal reaction vessel (3), and N is an integer greater than or equal to 2; inputting an iron-containing sulfate solution into some vertical reaction vessels (2), and inputting steam and oxygen into the vertical reaction vessels (2) to carry out a first iron removal treatment in the vertical reaction vessels (2) to obtain a first iron-removed slurry, wherein the iron removal efficiency during the first iron removal treatment is 16-24 kg•m-3•h-1; and inputting the first iron-removed slurry into the horizontal reaction vessel (3), and inputting steam and oxygen into the horizontal reaction vessel (3) to carry out a second iron removal treatment in the horizontal reaction vessel (3) to obtain a second iron-removed slurry, wherein the iron removal efficiency during the second iron removal treatment is 5-7 kg•m-3•h-1. The described method allows for continuous treatment of an iron-containing sulfate solution with continuous feeding and discharging, thereby effectively improving the iron removal efficiency, and ensuring a good iron removal effect.

Description

A method for removing iron from hematite using iron sulfate solutions Technical Field

[0001] This invention relates to a method for removing iron from hematite using an iron sulfate solution, belonging to the field of hydrometallurgy. Background Technology

[0002] The Iijima Zinc Plant in Japan was the first to build a zinc plant using the hematite removal process in 1971, with a production capacity of 200,000 tons / year of electrolytic zinc. The plant has been in operation for over 50 years and is currently running normally. Due to the plant's high level of secrecy, little is known about its actual production processes. Reports indicate that the plant uses SO2 flue gas to reduce the leaching residue, and some of the SO2 is converted into sulfuric acid, increasing the system's sulfuric acid content. To maintain acid balance, lime is added for neutralization to remove excess sulfate ions, resulting in a large amount of unsaleable gypsum slag. This gypsum slag has a high zinc content and requires separate treatment, leading to high production costs. The second plant in the world to use the hematite removal process was the Ruhr Zinc Plant in Germany, built in 1979 with a production capacity of 130,000 tons / year of electrolytic zinc. This plant discontinued the hematite removal process in 1993, reportedly due to high production costs and numerous system engineering problems, such as scaling within the reactor. The basic principle of hematite removal is a reaction under high temperature and high pressure conditions, removing Fe from the solution... 2+ Iron is removed by oxidation to form hematite slag. The chemical reaction formula is as follows:

[0003] 4FeSO4+O2+4H2O→2Fe2O3↓+4H2SO4.

[0004] There are two main problems with the iron removal method for hematite: one is Fe 2+ The first question concerns the reduction method, how to maintain the acid balance of the system to prevent the production of gypsum slag; the second is how to deal with the problem of iron slag deposition and scaling in the reactor.

[0005] Chinese invention patent specification CN104004913B discloses a method for removing iron from a zinc sulfate solution containing iron. The method includes: feeding the zinc sulfate solution containing iron into a vertical reactor and introducing steam and oxygen into the vertical reactor to perform a first iron removal treatment, obtaining a first iron-removed slurry; and feeding the first iron-removed slurry into a horizontal reactor and introducing steam and oxygen into the horizontal reactor to perform a second iron removal treatment, obtaining a second iron-removed slurry. During the reaction process, the vertical and horizontal reactors are combined, and the reaction temperature, oxygen partial pressure, and other conditions are consistent in both. Therefore, the iron deposition in both reactors is inevitably similar, and iron slag may deposit in both reactors. Consequently, after a period of operation, at least one of the vertical or horizontal reactors needs to be shut down for cleaning. Therefore, it is practically difficult to achieve continuous feeding and continuous discharge for continuous processing. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for removing iron from hematite in iron sulfate solution, so as to achieve continuous feeding and continuous discharge of iron sulfate solution for continuous processing.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0008] A method for removing iron from hematite in an iron sulfate solution includes the following steps:

[0009] S1. Provide an iron removal device;

[0010] The iron removal device includes N vertical reactors and 1 horizontal reactor, with the outlets of the N vertical reactors connected to the inlet of the horizontal reactor; N is an integer ≥ 2.

[0011] S2,

[0012] S2-1. An iron sulfate solution is fed into M vertical reactors, and steam and oxygen are introduced into the M vertical reactors to carry out the first iron removal treatment in the M vertical reactors to obtain the first iron-removed slurry.

[0013] S2-2. After the target running time of the M vertical reactors, stop feeding the iron sulfate solution into the M vertical reactors, and feed the iron sulfate solution into H other vertical reactors. Also feed steam and oxygen into the H vertical reactors to perform a first iron removal treatment, obtaining a first iron-removed slurry. During the operation of the H vertical reactors, clean the M vertical reactors.

[0014] S2-3. After the target running time of the H vertical reactors, stop feeding the iron sulfate solution into the H vertical reactors, and feed the iron sulfate solution into M other vertical reactors. Also, feed steam and oxygen into the M vertical reactors to perform a first iron removal treatment, obtaining a first iron-removed slurry. During the operation of the M vertical reactors, clean the H vertical reactors.

[0015] S2-4, Repeat S2-2 to S2-3;

[0016] During the first iron removal process, the temperature T1 inside the vertical reactor in operation is controlled at 185~199℃, the pressure at 1.6~1.9MPa, and the residence time at 0.4~0.9h, so that the iron removal efficiency is 16~24kg·m -3 ·h -1;

[0017] M is an integer ≥ 1 and < N; H is an integer ≥ 1 and ≤ (NM);

[0018] S3. The first iron-removed slurry is fed into a horizontal reactor, and steam and oxygen are introduced into the horizontal reactor to carry out a second iron removal treatment in the horizontal reactor to obtain a second iron-removed slurry.

[0019] During the second iron removal process, the temperature T2 inside the horizontal reactor is controlled at 165~180℃, the pressure at 1.6~1.9MPa, and the residence time at 1.8~3.5h, so that the iron removal efficiency is 5~7kg·m -3 ·h -1 T1 > T2.

[0020] In this invention, iron removal efficiency refers to the amount of iron removed per cubic meter of reaction volume per hour (iron removal amount kg·reactor volume m³). -3 ·Duration of stay h -1 (), where the amount of iron removed is expressed as the mass of Fe ions removed from the solution.

[0021] Furthermore, the iron removal device also includes a flash tank and a solid-liquid separation mechanism, and the horizontal reactor, flash tank and solid-liquid separation mechanism are connected in sequence; after S3, the second iron-removed slurry is input into the flash tank, and after cooling and depressurization, it is input into the solid-liquid separation mechanism for solid-liquid separation to obtain hematite slag and iron-removed liquid; preferably, the solid-liquid separation mechanism includes a thickener.

[0022] Preferably, the vertical reactor has a manhole.

[0023] Furthermore, N is 2-4.

[0024] Furthermore, the volume of the horizontal reactor is greater than the total volume of the vertical reactor in operation in S2. Preferably, the volume of the horizontal reactor is 2-6 times the total volume of the vertical reactor in operation in S2, and more preferably 3-5 times.

[0025] Furthermore, the target time is 20-80 days, preferably 30-60 days.

[0026] Furthermore, the iron content in the ferric sulfate solution is ≥20 g / L, preferably 21~40 g / L; the iron content in the liquid phase of the slurry after the first iron removal is <20 g / L, preferably 13~19 g / L. Therefore, under conditions of ferric sulfate solution containing more than 20 g / L of iron and high temperature of 185~199℃, the iron removal efficiency is 16~24 kg·m³. -3 ·h -1This process converts approximately 40% of the iron in the ferric sulfate solution into iron slag, which then partially deposits within the vertical reactor. With an iron content of <20 g / L in the liquid phase of the slurry after the first iron removal process, and under mesophilic conditions of 165-180℃, the iron removal efficiency is 5-7 kg / m³. -3 ·h -1 This allows approximately 60% of the iron in the remaining solution to enter the horizontal reactor and be converted into iron slag. The iron slag deposits very little in the horizontal reactor, allowing the entire iron removal process to be carried out continuously for a long time.

[0027] Furthermore, in S2, the total volume of the iron sulfate solution input into the vertical reactor in operation every 1 hour is 1-2.5 times the total volume of the vertical reactor in operation, preferably 1.25-2.25 times, and more preferably 1.5-2 times.

[0028] Furthermore, the difference between T1 and T2 is 5-25℃, preferably 10-20℃.

[0029] Furthermore, during the first iron removal process, the temperature T1 inside the vertical reactor in operation is controlled at 188~196℃, the pressure at 1.7~1.9MPa, and the residence time at 0.5~0.8h, so that the iron removal efficiency is 16.2~23.8kg·m -3 ·h -1 .

[0030] Furthermore, during the second iron removal process, the temperature T2 inside the horizontal reactor is controlled at 168~176℃, the pressure at 1.7~1.9MPa, and the residence time at 2~3.3h, so that the iron removal efficiency is 5.2~6.8kg·m³. -3 ·h -1 .

[0031] Optionally, the ferric sulfate solution is one of the following: ferric zinc sulfate solution, ferric nickel sulfate solution, and ferric copper sulfate solution.

[0032] Optionally, the valence state of iron in the iron sulfate solution is +2.

[0033] Referring to Figure 1, in the zinc smelting process, in order to produce a low-acid leachate, the returned acidic leachate is usually neutrally leached with the roasted sand produced by the fluidized bed roasting of zinc concentrate. After neutral leaching, the intermediate leaching solution can be sent for purification and electrolytic treatment. At the same time, the resulting intermediate leaching residue needs to be subjected to hot acid reduction leaching. The basic principle of hot acid reduction leaching is as follows: Under high temperature and high acid conditions, zinc ferrite in the intermediate leaching residue reacts to produce zinc sulfate and ferric sulfate. Ferric sulfate is reduced to ferrous sulfate under the action of the reducing agent zinc concentrate, thereby achieving the purpose of zinc ferrite leaching and iron reduction. The chemical reaction formula is as follows:

[0034] ZnO·Fe2O3+4H2SO4=ZnSO4+Fe2(SO4)3+4H2O;

[0035] ZnS + Fe2(SO4)3 = ZnSO4 + 2FeSO4 + S 0 ;

[0036] As can be seen from the above formula, using zinc concentrate as a reducing agent converts sulfur into elemental sulfur without affecting the acid balance of the system. However, the iron content in the leachate will inevitably remain high, resulting in an iron-containing zinc sulfate solution. Further iron removal treatment of the leachate using the iron removal method of this invention can effectively reduce the iron content in the solution system, preparing the solution for returning to the neutral leaching step and obtaining a low-iron intermediate leachate (which will then be sent to the purification and electrolysis processes). Therefore, the iron removal method of this invention plays an important role, at least in the field of zinc smelting.

[0037] Generally, both vertical and horizontal reactors are equipped with stirring devices. Therefore, in the hematite removal process, the strong and uniform stirring by the agitator can, to some extent, prevent iron slag deposition and ensure uniform reaction of the leaching solution. However, hematite slag is a viscous solid, so the effect of stirring in preventing deposition is limited. To prevent hematite slag deposition and scaling in reactors, the iron slag formed during the reaction must be discharged from the reactor promptly. If the residence time is too long, the iron slag cannot be discharged in time and easily deposits and forms scale; if the residence time is too short, the iron removal process is incomplete and fails to meet production requirements. Therefore, the traditional approach is to control appropriate parameters such as residence time to maximize iron removal efficiency while minimizing deposition and scaling. However, to achieve improved iron removal efficiency, this method often makes iron slag deposition and scaling unavoidable.

[0038] This invention connects N vertical reactors in parallel with a horizontal reactor, allowing each vertical reactor to serve as a backup for the others. Simultaneously, some vertical reactors are in operation while others are in shutdown or maintenance / cleaning status. Breaking with traditional approaches, it achieves an iron removal efficiency of 16-24 kg·m³ in the first iron removal process within the vertical reactors. -3 ·h -1 This process actively accelerates the conversion of iron to hematite, causing the iron slag formed during the reaction to scale within the corresponding vertical reactor. Consequently, the concentration of iron slag in the resulting slurry after the first iron removal is low, effectively reducing the possibility of scale formation during the subsequent second iron removal process. Furthermore, the initial iron concentration in the solution entering the second iron removal process is low, and by controlling the reaction conditions, the iron removal efficiency of the second iron removal process in the horizontal reactor is reduced to 5-7 kg·m³. -3 ·h -1This makes the iron removal reaction at this stage quite gradual, thus the possibility or amount of iron slag deposition in the horizontal reactor is very low, and the iron removal effect can be well guaranteed after two stages of iron removal. Furthermore, the vertical reactors can be operated and cleaned alternately (periodically through manholes), allowing both the first and second iron removal processes to be carried out continuously, ensuring the continuous operation of the entire iron removal process and guaranteeing a good iron removal effect. Therefore, the iron removal method of this invention can effectively solve the problem of continuous process operation caused by iron slag deposition and scaling in the reactor during the iron removal process of ferric sulfate, and can guarantee a good iron removal effect.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] The iron removal method of the present invention can realize continuous feeding and continuous discharge of iron sulfate solution, effectively improving iron removal efficiency and ensuring good iron removal effect.

[0041] In the iron removal process of this invention, some iron is deposited and scaled in the vertical reactor, which can effectively reduce the possibility of deposit and scale formation in the downstream horizontal reactor. Furthermore, the continuous operation and cleaning of each vertical reactor in turn effectively ensures the iron removal process.

[0042] This invention can use zinc concentrate as a reducing agent, eliminating the need for additional reducing agents, thus saving production costs. It does not increase sulfuric acid, maintains the acid balance of the system, and does not produce gypsum slag. Attached Figure Description

[0043] Figure 1 is a schematic diagram of the smelting process of zinc concentrate.

[0044] Figure 2 is a simplified structural diagram of an iron removal device according to the present invention.

[0045] Figure 3 is the XRD pattern of hematite slag obtained during the first iron removal treatment in Embodiment 2 of the present invention. Detailed Implementation

[0046] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" appearing below only indicate that they correspond to the upper, lower, left, and right directions of the accompanying drawings themselves, and do not limit the structure. Unless otherwise specified, the relevant percentages refer to mass percentages. Example 1

[0047] This embodiment relates to a method for processing zinc concentrate, including the following steps:

[0048] Zinc concentrate is roasted to produce roasted sand, and the resulting flue gas is sent to produce acid.

[0049] The calcined sand is subjected to neutral leaching, waste electrolytic solution is added, the temperature is controlled at 60-70℃, and the process is carried out for 1-2 hours. The final pH is 5.0-5.2, producing intermediate leaching residue. The intermediate leaching solution is then sent for purification, electrolysis, and casting to produce electrolytic zinc.

[0050] The intermediate leaching residue is subjected to hot acid reduction leaching, with the addition of waste electrolytic liquid and zinc concentrate. The temperature is controlled at 90-95℃ for 3-4 hours, and the final acid concentration is 50-70g / L. The resulting leachate is then sent to pyrometallurgical slag treatment.

[0051] The leachate is pre-neutralized by adding calcined sand, controlling the temperature at 60-65℃, the time at 0.5-1.5h, and the final pH at 1.0-2.0. The pre-neutralized residue is returned to neutral leaching, and the pre-neutralized liquid is the pre-iron removal liquid (iron concentration of 20-40g / L in zinc sulfate solution). Example 2

[0052] The method for removing iron from hematite using iron-containing zinc sulfate solution in this embodiment includes the following steps:

[0053] S1. Provide an iron removal device;

[0054] The iron removal device includes a pump 1, two vertical reactors 2 and one horizontal reactor 3, a flash tank 4, a solid-liquid separation mechanism 5, a steam delivery pipeline 15, and an oxygen delivery pipeline 16. The horizontal reactor, flash tank, and solid-liquid separation mechanism are connected in sequence. The outlets of the two vertical reactors are connected in parallel to the inlet of the horizontal reactor. The solid-liquid separation mechanism includes a thickener. A first valve 8 is provided at the inlet of the vertical reactor 2, a second valve 9 is provided at the outlet of the vertical reactor 2, a first air inlet is provided at the bottom of the vertical reactor 2, and a third valve 10 is provided at the air inlet. A fourth valve 11 is provided at the inlet of the horizontal reactor 3. A fifth valve 13 is provided at the discharge port of reactor 3. Multiple second air inlets are provided at the bottom of the horizontal reactor 3. The outlet of pump 1 is connected to the inlets of two first valves 8, and the outlets of two second valves 9 are connected to the inlet of the fourth valve 11. The outlet of the fifth valve 13 is connected to the flash tank 4, and a sixth valve 14 is also provided on the pipeline between the fifth valve 13 and the flash tank 4. A seventh valve 12 is provided at the second air inlet. An eighth valve 6 is provided on the steam conveying pipeline 15, and a ninth valve 7 is provided on the oxygen conveying pipeline 16. The outlet of the eighth valve 6 is connected to the third valve 10 and the seventh valve 12 respectively, and the ninth valve 7 is connected to the third valve 10 and the seventh valve 12 respectively. Both the vertical and horizontal reactors are equipped with stirring mechanisms. The vertical reactor has a manhole.

[0055] S2,

[0056] S2-1. A zinc sulfate solution containing iron is introduced into a vertical reactor (referred to as "the first vertical reactor"), and steam and oxygen are introduced into the first vertical reactor to carry out the first iron removal treatment in the first vertical reactor to obtain the first iron-removed slurry.

[0057] S2-2. After the first vertical reactor has been running for the target time, stop feeding the zinc sulfate solution containing iron into the first vertical reactor, and feed the zinc sulfate solution containing iron into another vertical reactor (referred to as the "second vertical reactor"). Steam and oxygen are also fed into the second vertical reactor to perform the first iron removal treatment and obtain the first iron-removed slurry. During the operation of the second vertical reactor, the first vertical reactor is cleaned through the manhole to remove the deposited iron slag.

[0058] S2-3. After the second vertical reactor has been running for the target time, stop feeding the iron-containing zinc sulfate solution into the second vertical reactor, feed the iron-containing zinc sulfate solution into the first vertical reactor, and feed steam and oxygen into the first vertical reactor to perform the first iron removal treatment in the first vertical reactor to obtain the first iron-removed slurry; during the operation of the first vertical reactor, clean the second vertical reactor through the manhole to remove the deposited iron slag;

[0059] S2-4, Repeat S2-2 to S2-3;

[0060] During the first iron removal process, the temperature T1 inside the vertical reactor in operation is controlled at 195℃, the pressure at 1.75MPa, and the residence time at 0.8h, so that the iron removal efficiency is 23.75 kg·m³. -3 ·h -1 The target time is 30 days; the volume of the vertical reactor is 1 m³. 3 The iron content in the zinc sulfate solution was 38 g / L; the iron content in the liquid phase of the slurry after the first iron removal was 19 g / L; during this period, 32.76 kg of hematite slag (containing 58% Fe, its XRD pattern is shown in Figure 3) was produced; the input rate of the zinc sulfate solution was 1.25 m. 3 / h;

[0061] S3. The first iron-removed slurry is poured at a rate of 1.25m... 3 The feed is fed into a horizontal reactor at a rate of / h, and steam and oxygen are fed into the horizontal reactor to carry out a second iron removal treatment in the horizontal reactor to obtain a second iron-removed slurry;

[0062] During the second iron removal process, the temperature T2 inside the horizontal reactor is controlled at 180℃, the pressure at 1.75MPa, and the residence time at 3.2h, so that the iron removal efficiency is 5.31kg·m³. -3 ·h -1 The horizontal reactor has a volume of 4m³. 3 During this period, 118.20 kg of hematite slag (containing 57.5% iron) was produced.

[0063] S4. The second iron-removed slurry is fed into a flash tank. After cooling and depressurization, it is fed into a solid-liquid separation mechanism for solid-liquid separation to obtain hematite slag and iron-removed liquid (containing 2g / L of iron).

[0064] The results showed that the vertical reactor had a cleaning cycle of 30 days; after 150 days of continuous operation, the horizontal reactor showed no significant scaling inside. Example 3

[0065] The method for removing iron from hematite using iron-containing zinc sulfate solution in this embodiment includes the following steps:

[0066] S1. Provide the iron removal device as described in Example 2;

[0067] S2,

[0068] S2-1. A zinc sulfate solution containing iron is introduced into a vertical reactor (referred to as "the first vertical reactor"), and steam and oxygen are introduced into the first vertical reactor to carry out the first iron removal treatment in the first vertical reactor to obtain the first iron-removed slurry.

[0069] S2-2. After the first vertical reactor has been running for the target time, stop feeding the zinc sulfate solution containing iron into the first vertical reactor, and feed the zinc sulfate solution containing iron into another vertical reactor (referred to as the "second vertical reactor"). Steam and oxygen are also fed into the second vertical reactor to perform the first iron removal treatment and obtain the first iron-removed slurry. During the operation of the second vertical reactor, the first vertical reactor is cleaned through the manhole to remove the deposited iron slag.

[0070] S2-3. After the second vertical reactor has been running for the target time, stop feeding the iron-containing zinc sulfate solution into the second vertical reactor, feed the iron-containing zinc sulfate solution into the first vertical reactor, and feed steam and oxygen into the first vertical reactor to perform the first iron removal treatment in the first vertical reactor to obtain the first iron-removed slurry; during the operation of the first vertical reactor, clean the second vertical reactor through the manhole to remove the deposited iron slag;

[0071] S2-4, Repeat S2-2 to S2-3;

[0072] During the first iron removal process, the temperature T1 inside the vertical reactor in operation is controlled at 190℃, the pressure at 1.70MPa, and the residence time at 0.65h, so that the iron removal efficiency is 18.48 kg·m³. -3 ·h -1 The target time is 40 days; the volume of the vertical reactor is 1 m³. 3 The iron content in the zinc sulfate solution was 30 g / L; the iron content in the liquid phase of the slurry after the first iron removal was 18 g / L; during this period, 21.45 kg of hematite slag (containing 56% Fe) was produced; the input rate of the zinc sulfate solution was 1.54 m. 3 / h;

[0073] S3, the first iron-removed slurry is poured at 1.54m 3 The feed is fed into a horizontal reactor at a rate of / h, and steam and oxygen are fed into the horizontal reactor to carry out a second iron removal treatment in the horizontal reactor to obtain a second iron-removed slurry;

[0074] During the second iron removal process, the temperature T2 inside the horizontal reactor is controlled at 175℃, the pressure at 1.70MPa, and the residence time at 2.6h, so that the iron removal efficiency is 6.23kg·m³. -3 ·h -1 The horizontal reactor has a volume of 4m³. 3 During this period, 116.1 kg of hematite slag (containing 55.8% iron) was produced.

[0075] S4. The slurry after the second iron removal is fed into the flash tank. After cooling and depressurization, it is fed into the solid-liquid separation mechanism for solid-liquid separation to obtain hematite slag and iron-removed liquid (containing 1.8 g / L of iron).

[0076] The results showed that the cleaning cycle for the vertical reactor was 40 days; after 160 days of continuous operation, no significant scaling occurred inside the horizontal reactor. Example 4

[0077] The method for removing iron from hematite using iron-containing zinc sulfate solution in this embodiment includes the following steps:

[0078] S1. Provide the iron removal device as described in Example 2;

[0079] S2,

[0080] S2-1. A zinc sulfate solution containing iron is introduced into a vertical reactor (referred to as "the first vertical reactor"), and steam and oxygen are introduced into the first vertical reactor to carry out the first iron removal treatment in the first vertical reactor to obtain the first iron-removed slurry.

[0081] S2-2. After the first vertical reactor has been running for the target time, stop feeding the zinc sulfate solution containing iron into the first vertical reactor, and feed the zinc sulfate solution containing iron into another vertical reactor (referred to as the "second vertical reactor"). Steam and oxygen are also fed into the second vertical reactor to perform the first iron removal treatment and obtain the first iron-removed slurry. During the operation of the second vertical reactor, the first vertical reactor is cleaned through the manhole to remove the deposited iron slag.

[0082] S2-3. After the second vertical reactor has been running for the target time, stop feeding the iron-containing zinc sulfate solution into the second vertical reactor, feed the iron-containing zinc sulfate solution into the first vertical reactor, and feed steam and oxygen into the first vertical reactor to perform the first iron removal treatment in the first vertical reactor to obtain the first iron-removed slurry; during the operation of the first vertical reactor, clean the second vertical reactor through the manhole to remove the deposited iron slag;

[0083] S2-4, Repeat S2-2 to S2-3;

[0084] During the first iron removal process, the temperature T1 inside the vertical reactor in operation is controlled at 185℃, the pressure at 1.60MPa, and the residence time at 0.55h, so that the iron removal efficiency is 18.2kg·m³. -3 ·h -1 The target time is 50 days; the volume of the vertical reactor is 1 m³. 3 The iron content in the zinc sulfate solution was 25 g / L; the iron content in the liquid phase of the slurry after the first iron removal was 15 g / L; during this period, 18.2 kg of hematite slag (containing 55% Fe) was produced; the input rate of the zinc sulfate solution was 1.82 m. 3 / h;

[0085] S3, the first iron-removed slurry is poured at 1.82m 3 The feed is fed into a horizontal reactor at a rate of / h, and steam and oxygen are fed into the horizontal reactor to carry out a second iron removal treatment in the horizontal reactor to obtain a second iron-removed slurry;

[0086] During the second iron removal process, the temperature T2 inside the horizontal reactor is controlled at 170℃, the pressure at 1.60MPa, and the residence time at 2.2h, so that the iron removal efficiency is 6.05kg·m³. -3 ·h -1 The horizontal reactor has a volume of 4m³. 3 During this period, 96.8 kg of hematite slag (containing 55% iron) was produced.

[0087] S4. The slurry after the second iron removal is fed into the flash tank. After cooling and depressurization, it is fed into the solid-liquid separation mechanism for solid-liquid separation to obtain hematite slag and iron-removed liquid (containing 1.7g / L of iron).

[0088] The results showed that the vertical reactor had a cleaning cycle of 50 days; after 175 days of continuous operation, the horizontal reactor showed no significant scaling inside. Example 5

[0089] The method for removing iron from hematite using iron-containing zinc sulfate solution in this embodiment includes the following steps:

[0090] S1. Provide the iron removal device as described in Example 2;

[0091] S2,

[0092] S2-1. A zinc sulfate solution containing iron is introduced into a vertical reactor (referred to as "the first vertical reactor"), and steam and oxygen are introduced into the first vertical reactor to carry out the first iron removal treatment in the first vertical reactor to obtain the first iron-removed slurry.

[0093] S2-2. After the first vertical reactor has been running for the target time, stop feeding the zinc sulfate solution containing iron into the first vertical reactor, and feed the zinc sulfate solution containing iron into another vertical reactor (referred to as the "second vertical reactor"). Steam and oxygen are also fed into the second vertical reactor to perform the first iron removal treatment and obtain the first iron-removed slurry. During the operation of the second vertical reactor, the first vertical reactor is cleaned through the manhole to remove the deposited iron slag.

[0094] S2-3. After the second vertical reactor has been running for the target time, stop feeding the iron-containing zinc sulfate solution into the second vertical reactor, feed the iron-containing zinc sulfate solution into the first vertical reactor, and feed steam and oxygen into the first vertical reactor to perform the first iron removal treatment in the first vertical reactor to obtain the first iron-removed slurry; during the operation of the first vertical reactor, clean the second vertical reactor through the manhole to remove the deposited iron slag;

[0095] S2-4, Repeat S2-2 to S2-3;

[0096] During the first iron removal process, the temperature T1 inside the vertical reactor in operation is controlled at 185℃, the pressure at 1.60MPa, and the residence time at 0.5h, so that the iron removal efficiency is 16.0 kg·m³. -3 ·h -1 The target time is 60 days; the volume of the vertical reactor is 1 m³. 3The iron content in the zinc sulfate solution was 21 g / L; the iron content in the liquid phase of the slurry after the first iron removal was 13 g / L; during this period, 14.55 kg of hematite slag (containing 55% Fe) was produced; the input rate of the zinc sulfate solution was 2 m. 3 / h;

[0097] S3, the first iron-removed slurry is poured at 2m 3 The feed is fed into a horizontal reactor at a rate of / h, and steam and oxygen are fed into the horizontal reactor to carry out a second iron removal treatment in the horizontal reactor to obtain a second iron-removed slurry;

[0098] During the second iron removal process, the temperature T2 inside the horizontal reactor is controlled at 165℃, the pressure at 1.60MPa, and the residence time at 2h, so that the iron removal efficiency is 5.6kg·m³. -3 ·h -1 The horizontal reactor has a volume of 4m³. 3 During this period, 80.72 kg of hematite slag (containing 55.5% iron) was produced.

[0099] S4. The slurry after the second iron removal is fed into the flash tank. After cooling and depressurization, it is fed into the solid-liquid separation mechanism for solid-liquid separation to obtain hematite slag and iron-removed liquid (containing 1.8 g / L of iron).

[0100] The results showed that the cleaning cycle for the vertical reactor was 60 days; after 200 days of continuous operation, no significant scaling occurred inside the horizontal reactor.

[0101] Comparative Example 1

[0102] Example 5 was repeated, except that during the first iron removal process, the temperature T1 inside the vertical reactor in operation was controlled at 180°C, the pressure at 1.60 MPa, and the residence time at 0.5 h, so that the iron removal efficiency was 15.5 kg·m³. -3 ·h -1 .

[0103] The results showed that the cleaning cycle for the vertical reactor was 65 days; after 160 days of continuous operation, iron slag scaling appeared inside the horizontal reactor. Example 6

[0104] Example 5 was repeated, except that during the first iron removal process, the temperature T1 inside the vertical reactor in operation was controlled at 198°C, the pressure at 1.60 MPa, and the residence time at 0.5 h, so that the iron removal efficiency was 24 kg·m³. -3 ·h -1 .

[0105] The results showed that the cleaning cycle for the vertical reactor was 30 days; after 200 days of continuous operation, no significant scaling occurred inside the horizontal reactor.

[0106] Comparative Example 2

[0107] Example 5 was repeated, except that during the first iron removal process, the temperature T1 inside the vertical reactor in operation was controlled at 205°C, the pressure at 1.90 MPa, and the residence time at 0.5 h, so that the iron removal efficiency was 24.5 kg·m³. -3 ·h -1 .

[0108] The results showed that the cleaning cycle for the vertical reactor was 20 days; after 200 days of continuous operation, no significant scaling occurred inside the horizontal reactor. At this point, the cleaning cycle for the vertical reactor was too short, potentially increasing the workload of cleaning.

[0109] Comparative Example 3

[0110] Example 5 was repeated, except that during the first iron removal treatment, the input rate of the iron-containing zinc sulfate solution was 2.86 m. 3 / h, residence time is 0.35h; during the second iron removal process, residence time is 1.40h.

[0111] The results showed that the iron content in the liquid phase of the slurry after the first iron removal was 15.4 g / L, while the iron content in the liquid after the second iron removal was 8.68 g / L. At this point, the high iron content in the liquid after iron removal negatively impacted subsequent processes.

[0112] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

Claims

1. A method for removing iron from hematite in an iron sulfate solution, characterized in that, Includes the following steps: S1. Provide an iron removal device; wherein the iron removal device includes N vertical reactors and 1 horizontal reactor, the outlets of the N vertical reactors are connected to the inlet of the horizontal reactor; N is an integer ≥2; S2, S2-1, The iron sulfate solution is fed into M vertical reactors, and steam and oxygen are fed into the M vertical reactors to carry out the first iron removal treatment in the M vertical reactors to obtain the first iron removal slurry; S2-2. After the target running time of the M vertical reactors, stop feeding the iron sulfate solution into the M vertical reactors, and feed the iron sulfate solution into H other vertical reactors. Also feed steam and oxygen into the H vertical reactors to perform a first iron removal treatment, obtaining a first iron-removed slurry. During the operation of the H vertical reactors, clean the M vertical reactors. S2-3. After the target running time of the H vertical reactors, stop feeding the iron sulfate solution into the H vertical reactors, and feed the iron sulfate solution into M other vertical reactors. Also, feed steam and oxygen into the M vertical reactors to perform a first iron removal treatment, obtaining a first iron-removed slurry. During the operation of the M vertical reactors, clean the H vertical reactors. S2-4, repeat S2-2~S2-3; wherein, during the first iron removal treatment, the temperature T1 inside the vertical reactor in operation is controlled at 185~199℃, the pressure at 1.6~1.9MPa, and the residence time at 0.4~0.9h, so that the iron removal efficiency is 16~24kg·m -3 ·h -1 ; M is an integer ≥1 and <N; H is an integer ≥1 and ≤ (NM); S3, the first iron-removed slurry is input into a horizontal reactor, and steam and oxygen are input into the horizontal reactor to carry out a second iron removal treatment in the horizontal reactor to obtain a second iron-removed slurry; wherein, during the second iron removal treatment, the temperature T2 in the horizontal reactor is controlled at 165~180℃, the pressure is 1.6~1.9MPa, and the residence time is 1.8-3.5h, so that the iron removal efficiency is 5~7kg·m -3 ·h -1 T1 > T2.

2. The method for removing iron from hematite according to claim 1, characterized in that, The iron removal device also includes a flash tank and a solid-liquid separation mechanism. The horizontal reactor, flash tank and solid-liquid separation mechanism are connected in sequence. After S3, the second iron-removed slurry is input into the flash tank. After cooling and depressurization, it is input into the solid-liquid separation mechanism for solid-liquid separation to obtain hematite slag and iron-removed liquid.

3. The iron removal method according to claim 2, characterized in that, The solid-liquid separation mechanism includes a thickener; preferably, the vertical reactor has a manhole.

4. The method for removing iron from hematite according to claim 1, characterized in that, N is 2-4.

5. The method for removing iron from hematite according to claim 1, characterized in that, The volume of the horizontal reactor is greater than the total volume of the vertical reactor in operation in S2. Preferably, the volume of the horizontal reactor is 2-6 times the total volume of the vertical reactor in operation in S2, and more preferably 3-5 times.

6. The method for removing iron from hematite according to claim 1, characterized in that, The target time is 20-80 days, preferably 30-60 days.

7. The method for removing iron from hematite according to claim 1, characterized in that, The iron content in the iron sulfate solution is ≥20 g / L, preferably 21~40 g / L; the iron content in the liquid phase of the slurry after the first iron removal is <20 g / L, preferably 13~19 g / L.

8. The method for removing iron from hematite according to claim 1, characterized in that, The difference between T1 and T2 is 5-25℃, preferably 10-20℃.

9. The method for removing iron from hematite according to any one of claims 1-8, characterized in that, During the first iron removal process, the temperature T1 inside the vertical reactor in operation is controlled at 188~196℃, the pressure at 1.7~1.9MPa, and the residence time at 0.5~0.8h, so that the iron removal efficiency is 16.2~23.8kg·m³. -3 ·h -1 .

10. The method for removing iron from hematite according to any one of claims 1-8, characterized in that, During the second iron removal process, the temperature T2 inside the horizontal reactor is controlled at 168~176℃, the pressure at 1.7~1.9MPa, and the residence time at 2-3.3h, so that the iron removal efficiency is 5.2~6.8kg·m³. -3 ·h -1 .

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