Three-stage coupling process for refining nickel-containing waste into nickel alloy and obtained nickel alloy

Abstract

The invention belongs to the field of waste metal refining, and particularly relates to a three-stage coupling process for refining nickel-containing waste into nickel alloy and the obtained nickel alloy. According to the method, the nickel-containing waste is pretreated and comprehensively utilized by utilizing the component characteristics of the nickel-containing waste, the aluminum element is extracted and utilized by adopting a soda lime sintering method, and a byproduct aluminum hydroxide product is sold to obtain profits. After the aluminum element is extracted, the nickel element is concentrated and enriched, the harmful substance alkali is utilized to participate in the aluminum extraction chemical reaction, and the harmful substance is changed into resources. And the dealuminated tailings are used for smelting nickel alloy, so that the production energy consumption is greatly reduced, the production benefit is greatly improved, and the comprehensive benefit is obviously increased.

Description

Technical Field

[0001] The present invention belongs to the field of waste metal refining, and particularly relates to a three-stage coupling process for refining nickel-containing waste into nickel alloy and the obtained nickel alloy. Background Art

[0002] The main chemical components of nickel-containing waste are: about 67% of Al2O3, about 7.7% of Na2O, about 7.73% of NiO, about 3.8% of SiO2, about 3.3% of Fe2O3, and about 0.91% of CaO. The existing production process for recycling nickel-containing waste to smelt nickel alloy directly presses the powdered nickel-containing waste into spheres, dries and mixes the ingredients and then smelts nickel alloy products in a furnace. Since the nickel-containing waste has a high alumina content, a low nickel element content, and contains harmful substances such as alkali, during the smelting process, the energy consumption is too high, the efficiency is low, and valuable elements such as aluminum and sodium are wasted.

[0003] More specifically, the existing nickel recovery technology process for nickel-containing waste is to smelt nickel alloy products by electrothermal carbon reduction method. Since the alumina content in the raw materials is too high, its melting temperature is as high as 1900°C, and the nickel element and alumina are associated together, and the nickel element must be reduced under the condition of high-temperature melting. In order to accelerate the melting of alumina and reduce the melting temperature, a smelting agent, fluorite calcium fluoride, is usually added during smelting, which will cause serious corrosion of the furnace lining and increase the cost. The basicity index is a key parameter for adjusting the material ratio in the smelting furnace. The ternary basicity CaO / (SiO2 + Al2O3) is between 0.4 and 0.6, and is adjusted to the best effect according to the furnace condition. The basicity of the raw materials in the traditional process is 0.91 / (3.8 + 67) = 0.013. To make the basicity of the raw materials to be fed into the furnace reach at least 0.4, 22% of limestone and 5% of fluorite need to be added, thus increasing the melting energy consumption of 27% of auxiliary materials.

[0004] The disadvantages of the existing technology are:

[0005] 1. The content of valuable metal nickel in the raw materials is low, the production capacity is small, and the production cost is high. Only 812 kg of nickel metal is recovered per furnace.

[0006] 2. There are many auxiliary raw materials, and the smelting energy consumption is high. 25.86 kWh of electricity is consumed for every 1 kg of nickel metal recovered, and the consumption is large.

[0007] 3. The useful element aluminum becomes waste residue after smelting, resulting in waste and loss of about 90% of alumina.

[0008] 4. The alkali in the raw materials is a harmful element, which will increase the harmless disposal cost of smelting and cause environmental pollution.

[0009] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the Invention

[0010] To solve the problems existing in the prior art, the present invention provides a three-stage coupling process for refining nickel-containing waste into nickel alloy. The three-stage coupling process comprises the following steps:

[0011] (1) Sinter the nickel-containing waste with lime and soda to obtain nickel-depleted material and aluminum hydroxide;

[0012] (2) Mix the nickel-depleted material with sodium carbonate and limestone, grind and pelletize them in sequence to obtain a mixed material;

[0013] (3) Sinter the mixed material at high temperature to cause a chemical reaction between aluminum and alkali to obtain sodium aluminate clinker;

[0014] (4) Grind the sodium aluminate clinker with water and separate to obtain sodium aluminate liquid and tailings;

[0015] (5) Transfer the tailings into a rotary kiln for sintering, dehydration and forming to obtain granular sintered material;

[0016] (6) Transfer the sintered material into a refining electric arc furnace, add a reducing agent and a melting agent, and decompose and reduce it by high-temperature sintering to obtain nickel alloy.

[0017] Preferably, in step (1), the temperature of the lime and soda sintering is 1250-1300 °C and the sintering time is 2-3 hours.

[0018] Preferably, in step (2), during the mixing process, the alkali-aluminum ratio = (Na2O + K2O) / Al2O3 = 0.96-1.02, and the calcium-silicon ratio = CaO / SiO2 = 1.7-1.75.

[0019] Preferably, in step (3), the temperature of the high-temperature sintering is 1250-1300 °C and the high-temperature sintering time is 2-3 hours.

[0020] Preferably, in step (4), introduce CO2 gas into the sodium aluminate solution to react to produce aluminum hydroxide crystals, and obtain aluminum hydroxide products through concentration and separation.

[0021] Preferably, in step (5), the temperature of the sintering, dehydration and forming is 10-40 °C and the sintering, dehydration and forming time is 1-2 hours.

[0022] Preferably, in step (6), the reducing agent is coal and the melting agent is lime calcium;

[0023] The weight ratio of the sintered material, the reducing agent and the melting agent is 1:0.12:0.08;

[0024] The temperature of the refining electric arc furnace is 1600-1700 °C and the treatment time is 6-8 hours.

[0025] Based on the same inventive concept, the solution of the present invention is to further provide a nickel alloy obtained by the above-mentioned three-stage coupling process.

[0026] The beneficial effects of the present invention are as follows:

[0027] The present invention utilizes the characteristics of the components of nickel-containing waste, pre-treats and comprehensively utilizes it. By using the alkali lime sintering method, aluminum elements are extracted and utilized, and by-products of aluminum hydroxide are sold for profit. After the extraction of aluminum elements, nickel elements are concentrated and enriched, and the harmful substance alkali participates in the chemical reaction for aluminum extraction, turning harmful substances into resources. The tailings after de-aluminum enter the smelting of nickel alloy, greatly reducing the production energy consumption, significantly improving the production efficiency, and significantly increasing the comprehensive income.

[0028] More specifically:

[0029] 1. The lean nickel raw materials of nickel-containing waste are pre-treated before smelting to concentrate and enrich nickel elements and improve production capacity.

[0030] 2. Using the harmful element alkali in the raw materials as raw materials for aluminum extraction reactants, turning harmful substances into resources and turning waste into treasure.

[0031] 3. Extracting aluminum oxide from the raw materials to produce aluminum hydroxide products and increasing the production added value.

[0032] 4. After aluminum extraction, the aluminum oxide in the raw materials decreases, and its own alkalinity 21.6 / 19.87 + 10.7 = 0.7 meets the smelting requirements, reducing the addition of auxiliary raw materials, reducing energy consumption, reducing production costs, and improving production efficiency. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1 It is a flow chart of the three-stage coupling process.

[0035] Figure 2 It is a flow chart of the pre-de-aluminum process. Detailed Embodiments

[0036] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope protected by the present invention.

[0037] Example

[0038] This example provides a three - stage coupling process for refining nickel - containing waste into nickel alloy. The three - stage coupling process includes the following steps:

[0039] (1) Soda - lime sintering method: According to the physical and chemical properties of nickel - containing waste with high alumina content, the rotary kiln soda - lime sintering method is adopted to extract its alumina to produce aluminum hydroxide products for value - added sales.

[0040] The obtained nickel - poor material is mixed with sodium carbonate and limestone and ground in a ball mill to obtain a mixture. The alkali - to - alumina ratio = (Na2O + K2O) / Al2O3 = 0.96 - 1.02 (1 in this example), and the calcium - to - silica ratio = CaO / SiO2 = 1.7 - 1.75 (1.7 in this example). The mixture enters the rotary kiln and is sintered at a temperature of 1250 °C - 1300 °C (1300 °C in this example). Under high - temperature conditions, aluminum in the raw material reacts with alkali to produce sodium aluminate (Na2O·Al2O3) clinker. Then, it is ground with a low - molecular - ratio solution. The dissolution rates of Na2O and Al2O3 in the clinker are 94 - 96% and 92 - 94% respectively, and the total recovery rate of Al2O3 reaches 90%.

[0041] The obtained slurry after grinding is filtered by a filter press to be separated into sodium aluminate liquid and tailings (concentrated red mud). CO2 gas is introduced into the sodium aluminate solution to react to produce aluminum hydroxide crystals, and aluminum hydroxide products are obtained through concentration and separation.

[0042] The main chemical reaction equations of the soda - lime sintering method are as follows:

[0043] Al2O3 + Na2CO3 → Na2O·Al2O3 + CO2↑ (combination);

[0044] Na2O·Al2O3 + 4H2O → 2NaAl(OH)4 (dissolution);

[0045] 2NaOH + CO2 → Na2CO3 + H2O (decomposition);

[0046] NaAl(OH)4 → Al(OH)3↓ + NaOH (decomposition).

[0047] The composition of the tailings (concentrated red mud) obtained in this step is: about 22.82% NiO, about 10.7% Al2O3, about 19.87% SiO2, about 11.72% Fe2O3, about 2.74% Na2O, and about 21.6% CaO.

[0048] The more specific composition is shown in Table 1:

[0049] Table 1

[0050]

[0051]

[0052] The alumina recovery rate is 56.3%, and the recovery ratio is 84%. When converted, 800 kg of aluminum hydroxide is produced per ton of raw materials, accounting for 80%. The nickel element is concentrated to 22.82%, and the enrichment ratio is 2.93. The harmful alkali element Na2O is about 2.74%, achieving the purpose of reducing harm and utilization.

[0053] (2) Preparing nickel-enriched materials by rotary kiln sintering: Transfer the tail slag (concentrated red mud) after aluminum extraction into the rotary kiln for sintering and dehydrating to form granular shapes, so as to meet the requirements of the refining electric arc furnace for the shape of the raw materials entering the furnace.

[0054] (3) High-efficient production of nickel alloy smelting: The nickel alloy is smelted by the electric heating carbon reduction method of the refining electric arc furnace. According to the characteristics that the chemical components of the tail slag after aluminum extraction are composed of oxides, and taking advantage of the characteristics of the refining electric arc furnace such as fast heating, rapid reduction reaction, short smelting cycle, and high recovery efficiency, coal is scientifically and reasonably selected as the reducing agent, and lime calcium is used as the melting agent. The sintered materials are decomposed and reduced in the furnace at high temperature to synthesize nickel alloy products. The metal content in the enriched sintered materials increases, and the hourly production capacity increases by 3 times, achieving low-carbon and high-efficient production. The composition of the final nickel alloy product is shown in Table 2.

[0055] Table 2

[0056]

[0057]

[0058] High-temperature chemical reaction principle:

[0059] NiO + C = Ni + Co↑

[0060] Ni2O3 + C = 2Ni + 3Co↑

[0061] FeO + C = Fe + CO↑

[0062] The three-stage coupling process flow chart of this embodiment is as Figure 1 shown.

[0063] The pre-aluminum extraction process flow chart in step (1) is as Figure 2 shown.

[0064] Effect comparison

[0065] (1) Raw material ratio consumption and output of nickel alloy production before aluminum extraction

[0066] 1. Composition of nickel-aluminum raw materials: approximately 7.73% NiO, approximately 3.3% Fe2O3, approximately 67% Al2O3, approximately 7.7% NaO, approximately 3.8% SiO2. The more specific composition is shown in Table 3:

[0067] Table 3

[0068]

[0069]

[0070]

[0071] 2. The metal recovery rate is calculated according to a ratio of 92%. After conversion, 10.5 tons of raw materials are smelted to produce 1 ton of product, and the grade of the nickel alloy product is Ni 58%.

[0072] 3. Each smelting cycle is 6 hours. 15 tons of raw materials are smelted to produce 1.4 tons of Ni 58% nickel alloy products.

[0073] 4. Each smelting cycle consumes 21,000 degrees of electricity, and the power consumption per ton of product is 15,000 degrees.

[0074] 5. The nickel metal recovery amount per furnace is 812 kg.

[0075] (2) Raw material ratio, consumption and output of nickel alloy after dealumination

[0076] 1. Composition of sintered materials: approximately 22.82% Ni, approximately 10.7% Al2O3, approximately 19.87% SiO2, approximately 11.72% Fe2O3, approximately 2.74% Na2O.

[0077] 2. The metal recovery rate is calculated according to a ratio of 92%. After conversion, 4.3 tons of raw materials are smelted to produce 4.4 tons of products, and the grade of the nickel alloy product is Ni56%.

[0078] 3. Each smelting cycle is 6 hours. 15 tons of raw materials are smelted to produce 4.4 tons of Ni56% nickel alloy products.

[0079] 4. Each smelting cycle consumes 21,000 degrees of electricity, and the power consumption per ton of product is 4,800 degrees.

[0080] 5. The nickel metal recovery amount per furnace is 2,464 kg.

[0081] (3) Data comparison under the same smelting conditions before and after aluminum extraction is shown in Table 4.

[0082] Table 4

[0083]

[0084]

[0085] (4) The component comparison before and after dealumination is shown in Table 5 as follows.

[0086] Table 5

[0087] Molecular formula Before dealumination (%) After dealumination (%) Improvement rate <![CDATA[Al2O3]]> 67 10.7 Recovery rate 84% NiO 7.73 22.82 Concentration rate 295.2% <![CDATA[SiO2]]> 3.8 19.87 Increase 522.89% <![CDATA[Fe2O3]]> 3.3 11.72 Concentration rate 355.15% <![CDATA[Na2O]]> 7.7 2.74 Recovery rate 64.41% CaO 0.91 21.6 Increase 23.73%

[0088] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims described.

Claims

1. A three-stage coupling process for refining nickel-containing waste into nickel alloy, characterized in that, The three-stage coupling process includes the following steps: (1) Sinter the nickel-containing waste with lime and soda ash to obtain nickel-depleted material and aluminum hydroxide; (2) Mix the nickel-depleted material with sodium carbonate and limestone, grind and pelletize them in sequence to obtain a mixed material; (3) Sinter the mixed material at high temperature to cause a chemical reaction between aluminum and alkali to obtain sodium aluminate clinker; (4) Dissolve and separate the sodium aluminate clinker by water milling to obtain sodium aluminate liquid and tailings; (5) Transfer the tailings into a rotary kiln for sintering, dehydration and forming to obtain granular sintered material; (6) Transfer the sintered material into a refining electric arc furnace, add a reducing agent and a melting agent, and obtain a nickel alloy through high-temperature sintering, decomposition and reduction; 2. The three-stage coupling process for refining nickel-containing waste into nickel alloy according to claim 1, characterized in that, In step (1), the temperature of the lime and soda ash sintering is 1250-1300 °C, and the sintering time is 2-3 hours.

3. The three-stage coupling process for refining nickel-containing waste into nickel alloy according to claim 1, wherein, In step (2), during the mixing process, the alkali-aluminum ratio = (Na2O + K2O) / Al2O3 = 0.96-1.02, and the calcium-silicon ratio = CaO / SiO2 = 1.7-1.

75.

4. The three-stage coupling process for refining nickel-containing waste into nickel alloy according to claim 1, characterized in that, In step (3), the temperature of the high-temperature sintering is 1250-1300 °C, and the high-temperature sintering time is 2-3 hours.

5. The three-stage coupling process for refining nickel-containing waste into nickel alloy according to claim 1, characterized in that, In step (4), introduce CO2 gas into the sodium aluminate solution to react to produce aluminum hydroxide crystals, and obtain aluminum hydroxide products through concentration and separation.

6. The three-stage coupling process for refining nickel-containing waste into nickel alloy according to claim 1, characterized in that, In step (5), the temperature of the sintering, dehydration and forming is 10-40 °C, and the sintering, dehydration and forming time is 1-2 hours.

7. The three-stage coupling process for refining nickel-containing waste into nickel alloy according to claim 1, characterized in that, In step (6), the reducing agent is coal, and the melting agent is lime calcium; The weight ratio of the sintered material, the reducing agent and the melting agent is 1:0.12:0.08; The temperature of the refining electric arc furnace is 1600-1700 °C, and the treatment time is 6-8 hours.

8. The nickel alloy obtained by the three-stage coupling process according to any one of claims 1 to 7.

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