Method for recovering valuable elements in nickel-containing iron oxide slag
Through the process of primary reduction roasting-oxidation roasting-secondary reduction roasting, the problems of high energy consumption and difficult nickel recovery caused by high temperature operations in the existing technology are solved, and the high-value recycling of nickel-containing iron oxide slag is achieved. Pure iron-nickel alloy.
Patent Information
- Application Number
- CN202411580475.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-06
- Publication Date
- 2025-02-14
AI Technical Summary
The prior art requires high temperature operation when recycling nickel-containing iron oxide slag, resulting in high energy consumption and difficult to recover high value of the valuable element nickel.
The process of primary reduction roasting, oxidation roasting, and secondary reduction roasting is processed and converted into an iron-nickel alloy to achieve high-value recovery of valuable elements iron and nickel.
The process energy consumption is reduced and high-value recycling of iron and nickel is achieved. The product is pure iron-nickel alloy.
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Figure CN119433187A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of metallurgical solid waste resource utilization, and in particular to a method for recovering valuable elements in nickel-containing iron oxide slag. Background Art
[0002] In the high-grade nickel matte hydrometallurgy process, the oxygen-pressure iron removal process will produce a certain amount of oxygen-pressure slag, the main component of which is iron oxide, and it also contains about 2% nickel. Most of the nickel in the oxygen-pressure slag exists in the form of nickel sulfide and is wrapped by iron oxide, making it difficult to recycle. At present, oxygen-pressure slag is generally sold as an ironmaking raw material, and the nickel in it is not priced, resulting in the loss of valuable elements.
[0003] Currently, existing technologies for recycling oxygen-pressed slag require operating temperatures exceeding 1000°C (e.g., 1200°C), resulting in high energy consumption and high equipment requirements. In addition, the byproducts generated by current recycling methods for oxygen-pressed slag are mostly used in the construction field and have low value.
[0004] Therefore, there is an urgent need to develop a new recovery process for oxygen-pressed slag to achieve high-value recovery of valuable elements such as iron and nickel while reducing energy consumption.
[0005] In view of this, the present invention is proposed. Summary of the invention
[0006] The object of the present invention is to provide a method for recovering valuable elements in nickel-containing iron oxide slag, aiming to reduce energy consumption while achieving high-value recovery of the valuable elements iron and nickel.
[0007] The present invention is achieved in that:
[0008] In a first aspect, the present invention provides a method for recovering valuable elements in nickel-containing iron oxide slag, comprising:
[0009] Mixing nickel-containing iron oxide slag with a reducing agent to obtain a mixed material;
[0010] The mixed material is subjected to a reduction roasting to obtain a one-step reduction raw material;
[0011] The one-step reduction raw material is subjected to oxidative roasting to obtain a one-step oxidation material;
[0012] The one-step oxidation material is subjected to secondary reduction roasting to obtain an iron-nickel alloy.
[0013] In an optional embodiment, the primary reduction roasting has a roasting temperature of 700°C to 950°C and a roasting time of 30min to 120min;
[0014] Preferably, the primary reduction calcination has a calcination temperature of 800° C. to 900° C. and a calcination time of 80 min to 100 min.
[0015] In an alternative embodiment, the reducing agent is a carbon-based material;
[0016] Preferably, the carbon-based material is selected from at least one of anthracite powder and activated carbon.
[0017] In an optional embodiment, the theoretical amount of carbon is calculated based on the iron content in the nickel-containing iron oxide slag, and the mass ratio of the actual amount of carbon to the theoretical amount is controlled to be (1.1-1.5):1; preferably (1.10-1.25):1.
[0018] In an optional embodiment, during the oxidation roasting process, the roasting temperature is controlled to be 300° C. to 700° C., and the roasting time is 30 min to 90 min;
[0019] Preferably, during the oxidation roasting process, the roasting temperature is controlled to be 500° C. to 600° C., and the roasting time is controlled to be 50 min to 70 min.
[0020] In an optional embodiment, the oxidation roasting process is carried out in an oxygen-containing atmosphere;
[0021] Preferably, the volume fraction of oxygen in the oxygen-containing atmosphere is 25% to 30%;
[0022] Preferably, the waste gas generated during the oxidative roasting process is absorbed by aqueous ammonia to prepare ammonium sulfate.
[0023] In an optional embodiment, during the secondary reduction roasting process, the roasting temperature is controlled to be 700° C. to 1000° C., and the roasting time is 30 min to 90 min;
[0024] Preferably, during the secondary reduction roasting process, the roasting temperature is controlled to be 800° C. to 900° C., and the roasting time is controlled to be 50 min to 70 min.
[0025] In an optional embodiment, the secondary reduction roasting is carried out in a reducing atmosphere;
[0026] Preferably, in the reducing atmosphere, the mass ratio of carbon monoxide to hydrogen is (0.25-5.0):1;
[0027] Preferably, the reducing atmosphere is formed by mixing hydrogen and reducing gas generated during the primary reduction roasting process.
[0028] In an optional embodiment, the nickel-containing iron oxide slag contains iron oxide and nickel sulfide, and the mass fraction of nickel is 0.1% to 5%;
[0029] Preferably, the iron oxide is coated on the nickel sulfide.
[0030] In an optional embodiment, the nickel-containing iron oxide slag is oxygen-pressed slag produced by the oxygen-pressed iron removal step in the high-matte nickel hydrometallurgy process.
[0031] The present invention has the following beneficial effects: the present invention processes nickel-containing iron oxide slag (such as oxygen-pressed slag of iron oxide-coated nickel sulfide) through a process of primary reduction roasting-oxidation roasting-secondary reduction roasting, and the dense iron oxide can be transformed into loose iron element through primary reduction roasting, and the nickel sulfide can be transformed into nickel iron and ferrous sulfide at the same time, so that the sulfur is exposed; after oxidation roasting, the sulfur is transformed into sulfur dioxide for removal, and the iron and nickel are transformed into corresponding oxides; after secondary reduction roasting, a pure iron-nickel alloy is obtained. The process provided by the present invention does not require a particularly high temperature, can reduce process energy consumption, and can achieve high-value recovery of valuable elements iron and nickel. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.
[0033] Figure 1 A main flow chart of the recycling process provided by an embodiment of the present invention;
[0034] Figure 2 A flowchart of a recycling process provided by an embodiment of the present invention;
[0035] Figure 3 It is a schematic diagram of phase change in the process of primary reduction roasting-oxidation roasting-secondary reduction roasting;
[0036] Figure 4 XRD pattern of oxygen-pressed slag;
[0037] Figure 5 This is the XRD spectrum of the one-step reduction raw material;
[0038] Figure 6 This is the XRD spectrum of the one-step oxidation material;
[0039] Figure 7 This is the XRD pattern of nickel-iron alloy. DETAILED DESCRIPTION
[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.
[0041] Please refer to Figure 1 and Figure 2 The embodiment of the present invention provides a method for recovering valuable elements in nickel-containing iron oxide slag, comprising the following steps:
[0042] S1. Preparation of mixed materials
[0043] The nickel-containing iron oxide slag is evenly mixed with the reducing agent to obtain a mixed material for later use.
[0044] In some embodiments, the nickel-containing iron oxide slag contains iron oxide and nickel sulfide, and the mass fraction of nickel is 0.1% to 5%, such as 0.1%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, etc.
[0045] The recovery method provided in the embodiment of the present invention is also particularly suitable for the recovery of slag coated with iron oxide on nickel sulfide, such as the oxygen-pressed slag produced by the oxygen-pressed iron removal step in the high-matte nickel hydrometallurgy process. Through a special process of primary reduction roasting-oxidation roasting-secondary reduction roasting, the oxygen-pressed slag can be converted into an iron-nickel alloy, thereby achieving high-value recovery of the valuable elements iron and nickel.
[0046] In some embodiments, the reducing agent can be a carbon-based material, and the specific type is not limited, as long as it can reduce iron ions. In a preferred embodiment, the carbon-based material can be selected from at least one of anthracite powder and activated carbon, and the carbon-based material can be any one or two of the above. Anthracite powder can be a commercially available raw material, and the activated carbon can be waste activated carbon from the workshop to achieve waste recycling. Preferably, the selected activated carbon is wood / coal / coconut shell activated carbon that is scrapped from other processes in the workshop (such as oil removal and TOC removal).
[0047] Further, the theoretical amount of carbon is calculated from the iron content in the nickel-containing iron oxide slag, and the theoretical amount of carbon is calculated according to the molar amount of iron, and the theoretical amount of carbon corresponding to 1 mol of iron is 1.5 mol; then the theoretical carbon mass is calculated according to the obtained theoretical carbon amount, and the mass ratio of the actual amount of carbon to the theoretical amount is controlled to be (1.1-1.5): 1, such as 1.10: 1, 1.15: 1, 1.20: 1, 1.25: 1, 1.30: 1, 1.35: 1, 1.40: 1, 1.45: 1, 1.50: 1, etc., preferably (1.10-1.25): 1. It is preferable to control the amount of carbon within the above range so that the iron is fully reduced.
[0048] S2. Primary reduction roasting
[0049] The mixed material obtained from S1 is subjected to a reduction roasting to obtain a one-step reduction material. In the oxygen-pressed slag, the nickel sulfide is densely wrapped by the iron oxide, so that the nickel sulfide cannot be directly oxidized and roasted, and the process is extremely slow. Through the one-step reduction roasting, the dense iron oxide is transformed into loose iron element, and the nickel sulfide is transformed into nickel iron and ferrous sulfide, exposing the sulfur.
[0050] In some embodiments, the primary reduction roasting temperature is 700°C to 950°C, and the roasting time is 30 min to 120 min; preferably, the primary reduction roasting temperature is 800°C to 900°C, and the roasting time is 80 min to 100 min. The reaction is fully carried out by further adjusting the temperature and time of the reduction roasting.
[0051] Specifically, the calcination temperature of the primary reduction calcination can be 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, etc., and the calcination time can be 30min, 50min, 80min, 90min, 100min, 120min, etc.
[0052] S3, Oxidation roasting
[0053] The first-step reduction material is subjected to oxidative roasting to obtain a first-step oxidation material. After oxidative roasting, sulfur is converted into sulfur dioxide for removal, and iron and nickel are converted into corresponding oxides.
[0054] In some embodiments, during the oxidative roasting process, the roasting temperature is controlled to be 300°C to 700°C, and the roasting time is 30 minutes to 90 minutes; preferably, the roasting temperature is controlled to be 500°C to 600°C, and the roasting time is 50 minutes to 70 minutes. The roasting temperature and time of the oxidative roasting are controlled within the above ranges to fully remove sulfur.
[0055] Specifically, during the oxidation roasting process, the roasting temperature can be controlled to be 300°C, 400°C, 500°C, 550°C, 600°C, 700°C, etc., and the roasting time can be 30min, 40min, 50min, 60min, 70min, 80min, 90min, etc.
[0056] Furthermore, the oxidative roasting process is carried out in an oxygen-containing atmosphere, which may be an air atmosphere, preferably oxygen-enriched air, and the volume fraction of oxygen may be 25% to 30%, such as 25%, 26%, 27%, 28%, 29%, 30%, etc.
[0057] In some embodiments, the waste gas generated during the oxidative roasting process is absorbed by ammonia water to prepare ammonium sulfate, so that the waste gas is recovered to meet environmental protection requirements.
[0058] S4, secondary reduction roasting
[0059] The one-step oxidation material is subjected to secondary reduction roasting to obtain a pure iron-nickel alloy.
[0060] In some embodiments, during the secondary reduction roasting, the roasting temperature is controlled to be 700°C to 1000°C, and the roasting time is 30min to 90min; preferably, the roasting temperature is controlled to be 800°C to 900°C, and the roasting time is 50min to 70min. By adjusting the temperature and time of the secondary reduction roasting, a purer alloy product can be obtained.
[0061] Specifically, the calcination temperature of the secondary reduction calcination can be 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, etc.; the calcination time can be 30min, 40min, 50min, 60min, 70min, 80min, 90min, etc.
[0062] In some embodiments, the secondary reduction roasting is carried out in a reducing atmosphere, and the type of reducing atmosphere is not limited, such as hydrogen, carbon monoxide, etc. In a preferred embodiment, in the reducing atmosphere, the mass ratio of carbon monoxide to hydrogen is (0.25-5.0):1, and the purity of the product is further improved by regulating the composition of the reducing atmosphere. Specifically, in the reducing atmosphere, the mass ratio of carbon monoxide to hydrogen can be 0.25:1, 0.5:1, 1.0:1, 2.0:1, 3.0:1, 4.0:1, 5.0:1, etc. The embodiment of the present invention fully considers the recycling of tail gas, and the primary reducing gas can be added with hydrogen as a reducing agent for the second-step reduction to achieve low-carbon metallurgy.
[0063] It should be noted that the several stages of reaction provided in the embodiments of the present invention can be carried out in the same reactor, and the reaction conditions at each stage can be regulated by changing the redox atmosphere.
[0064] like Figure 3 As shown, the present invention provides a process of treating oxygen-containing pressed slag by a primary reduction roasting-oxidation roasting-secondary reduction roasting. The primary reduction roasting can transform dense iron oxide into loose iron element, and nickel sulfide into nickel iron and ferrous sulfide, exposing sulfur; after oxidation roasting, sulfur is transformed into sulfur dioxide for removal, and iron and nickel are transformed into corresponding oxides; after secondary reduction roasting, a pure iron-nickel alloy is obtained. The process has a low reaction temperature, and the product is an iron-nickel alloy that can be directly sold, realizing high-value recovery of iron and nickel.
[0065] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.
[0066] It should be noted that the composition of the oxygen-pressed slag used in the following examples and comparative examples is shown in Table 1:
[0067] Table 1 Chemical composition of oxygen pressed slag / wt%
[0068] element Fe Ni S But Can S content 55.22 1.999 2.237 0.4048 0.3928
[0069] The XRD pattern of the slag is as follows: Figure 4 shown.
[0070] Example 1
[0071] This embodiment provides a method for recovering valuable elements in nickel-containing iron oxide slag, the steps of which are as follows:
[0072] (1) Take 100 g of oxygen-pressed slag and 22.19 g of waste activated carbon (the theoretical amount of activated carbon is 17.75 g, and the mass ratio of the actual amount of activated carbon to the theoretical amount is 1.25:1), mix them evenly to obtain a mixed material.
[0073] (2) The above-mentioned mixed material was placed in a furnace and calcined at 850°C for 90 min to obtain a one-step reduction material. The XRD pattern is shown in FIG. Figure 5 shown.
[0074] (3) The one-step reduction material is placed in a furnace, air is introduced, and oxidatively calcined at 550°C for 60 min to obtain a one-step oxidation material. The XRD pattern is as follows: Figure 6 shown.
[0075] (4) The above-mentioned one-step oxidation material is placed in a furnace and reduced and calcined at 800°C for 60 min in a reducing atmosphere to obtain an iron-nickel alloy. The XRD pattern is as follows: Figure 7 As shown. The mass ratio of carbon monoxide to hydrogen in the reducing atmosphere is 0.25:1.
[0076] The results showed that the recovery rates of Fe and Ni were 99.5% and 99.6% respectively, and the product was iron-nickel powder (containing 0.009% sulfur).
[0077] The mechanism diagram of the recovery method provided by the embodiment of the present invention is as follows Figure 3 As shown, combined Figure 4-Figure 7 Can prove Figure 3 The reaction mechanism of Figure 4 It can be seen that the oxygen-pressed slag is mainly composed of Fe2O3; Figure 5 It can be seen that the one-step reduction transforms the dense iron oxide into loose iron, and at the same time, the nickel sulfide transforms into nickel iron and ferrous sulfide, exposing the sulfur. Figure 6 It can be seen that after the first-step reduction raw material is oxidized and roasted, sulfur is converted into sulfur dioxide and removed, and iron and nickel are converted into corresponding oxides; Figure 7 It can be seen that after the one-step oxidation material is subjected to secondary reduction roasting, a pure iron-nickel alloy is obtained.
[0078] Example 2
[0079] This embodiment provides a method for recovering valuable elements in nickel-containing iron oxide slag, the steps of which are as follows:
[0080] (1) Take 100 g of oxygen-pressed slag and 20.41 g of anthracite powder (the theoretical amount of anthracite powder is 17.75 g, and the mass ratio of the actual amount of anthracite powder to the theoretical amount is 1.15:1), mix them evenly to obtain a mixed material.
[0081] (2) The mixed material is placed in a furnace and subjected to reduction roasting at 900° C. for 90 min to obtain a one-step reduction material.
[0082] (3) The one-step reduction material is placed in a furnace, oxygen-enriched air (oxygen volume fraction is 28%) is introduced, and oxidative roasting is performed at 600° C. for 60 min to obtain a one-step oxidation material.
[0083] (4) placing the above one-step oxidation material in a furnace and performing reduction roasting at 850° C. for 90 min in a reducing atmosphere to obtain an iron-nickel alloy, wherein the mass ratio of carbon monoxide to hydrogen in the reducing atmosphere is 0.25:1.
[0084] The results showed that the recovery rates of Fe and Ni were 99.0% and 99.4% respectively, and the product was iron-nickel powder (containing 0.005% sulfur). Figure 7 similar.
[0085] Comparative Example 1
[0086] This comparative example provides a method for recovering valuable elements in nickel-containing iron oxide slag, which differs from Example 1 only in that only steps (1) and (2) are performed. The steps are as follows:
[0087] (1) Take 100 g of oxygen-pressed slag and 22.19 g of waste activated carbon, mix them evenly to obtain a mixed material.
[0088] (2) The mixed material is placed in a furnace and reduced and calcined at 850°C for 90 minutes to obtain a one-step reduction material.
[0089] The results show that the recovery rates of Fe and Ni are 99.0% and 98.5% respectively, and the product is sulfur-containing iron-nickel powder (sulfur content 4.35%). Figure 5 shown.
[0090] Comparative Example 2
[0091] This comparative example provides a method for recovering valuable elements in nickel-containing iron oxide slag, which differs from Example 1 only in that the roasting time in step (3) is reduced.
[0092] Here are the steps:
[0093] (1) Take 100 g of oxygen-pressed slag and 22.19 g of waste activated carbon, mix them evenly to obtain a mixed material.
[0094] (2) The mixed material is placed in a furnace and reduced and calcined at 850°C for 90 minutes to obtain a one-step reduction material.
[0095] (3) The one-step reduction material is placed in a furnace, air is introduced, and oxidative roasting is performed at 550° C. for 30 min to obtain a one-step oxidation material.
[0096] (4) The above-mentioned one-step oxidation material is placed in a furnace and reduction-baked at 800° C. for 60 min to obtain an iron-nickel alloy.
[0097] The results showed that the recovery rates of Fe and Ni were 99.3% and 99.5% respectively, and the product was sulfur-containing iron-nickel powder (sulfur content 1.5%). Figure 7 similar.
[0098] Comparative Example 3
[0099] This comparative example provides a method for recovering valuable elements in nickel-containing iron oxide slag, and the specific steps are as follows: 100g of oxygen-pressed slag is taken and roasted at 850°C for 180min in oxygen-enriched air (oxygen volume fraction is 28%). Then, it is reduced and roasted at 800°C for 60min in a reducing atmosphere to obtain an iron-nickel alloy. The mass ratio of carbon monoxide to hydrogen in the reducing atmosphere is 0.25:1.
[0100] The results show that the iron-nickel alloy contains 1.92% sulfur (the sulfur removal rate is 45.96%), and is an iron-nickel alloy containing impure sulfur.
[0101] Comparative Example 3 shows that it is difficult to oxidize sulfur in oxygen-pressed slag by direct roasting, further illustrating the necessity of one-step reduction.
[0102] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for recovering valuable elements in nickel-containing iron oxide slag, characterized in that: include: Mixing nickel-containing iron oxide slag with a reducing agent to obtain a mixed material; The mixed material is subjected to a reduction roasting to obtain a one-step reduction material; The one-step reduction raw material is subjected to oxidative roasting to obtain a one-step oxidation material; The one-step oxidation material is subjected to secondary reduction roasting to obtain an iron-nickel alloy.
2. The recycling method according to claim 1, characterized in that: The primary reduction roasting has a roasting temperature of 700°C to 950°C and a roasting time of 30min to 120min; Preferably, the primary reduction calcination has a calcination temperature of 800° C. to 900° C. and a calcination time of 80 min to 100 min.
3. The recycling method according to claim 2, characterized in that: The reducing agent is a carbon-based material; Preferably, the carbon-based material is selected from at least one of anthracite powder and activated carbon.
4. The recycling method according to claim 3, characterized in that: The theoretical amount of carbon is calculated from the iron content in the nickel-containing iron oxide slag, and the mass ratio of the actual amount of carbon to the theoretical amount is controlled to be (1.1-1.5):1; preferably (1.10-1.25):
1.
5. The recycling method according to claim 1, characterized in that: During the oxidation roasting process, the roasting temperature is controlled to be 300° C. to 700° C., and the roasting time is 30 min to 90 min. Preferably, during the oxidation roasting process, the roasting temperature is controlled to be 500° C. to 600° C., and the roasting time is controlled to be 50 min to 70 min.
6. The recycling method according to claim 5, characterized in that: The oxidation roasting process is carried out in an oxygen-containing atmosphere; Preferably, the volume fraction of oxygen in the oxygen-containing atmosphere is 25%-30%; Preferably, the waste gas generated during the oxidative roasting process is absorbed by aqueous ammonia to prepare ammonium sulfate.
7. The recycling method according to claim 1, characterized in that: During the secondary reduction roasting process, the roasting temperature is controlled to be 700°C to 1000°C, and the roasting time is 30min to 90min; Preferably, during the secondary reduction roasting process, the roasting temperature is controlled to be 800° C. to 900° C., and the roasting time is controlled to be 50 min to 70 min.
8. The recycling method according to claim 7, characterized in that: The secondary reduction roasting is carried out in a reducing atmosphere; Preferably, in the reducing atmosphere, the mass ratio of carbon monoxide to hydrogen is (0.25-5.0):1; Preferably, the reducing atmosphere is formed by mixing hydrogen and reducing gas generated during the primary reduction roasting process.
9. The recycling method according to claim 1, characterized in that: The nickel-containing iron oxide slag contains iron oxide and nickel sulfide, and the mass fraction of nickel is 0.1%-5%; Preferably, the iron oxide is coated on the nickel sulfide.
10. The recycling method according to claim 9, characterized in that: The nickel-containing iron oxide slag is oxygen-pressed slag produced by the oxygen-pressed iron removal process in the high-matte nickel hydrometallurgy process.