A method for recovering valuable elements from oil residue discharged from slurry bed catalyst

Abstract

The present invention provides a method for recovering valuable elements from the oil residue discharged from the slurry bed catalyst, and relates to the technical field of solid waste treatment. The present invention sequentially performs medium-temperature oxidation roasting and high-temperature reduction cracking on the oil residue discharged from the slurry bed catalyst to obtain cracking residue; the cracking residue is mixed with an alkaline oxidation leaching agent for leaching to obtain nickel-containing leaching residue and molybdenum- and vanadium-containing leaching solution; the molybdenum- and vanadium-containing leaching solution is mixed with an ammonium salt for vanadium precipitation to obtain an ammonium metavanadate product and a vanadium precipitation tail liquid; the vanadium precipitation tail liquid is mixed with an acid reagent for neutralization and molybdenum precipitation to obtain crude molybdic acid; the crude molybdic acid is sequentially calcined, alkali dissolved, ion exchanged for impurity removal and neutralized to obtain a molybdic acid product. The present invention can greatly improve the leaching rate of molybdenum, vanadium and nickel, and realize the comprehensive recovery of valuable elements. The comprehensive recovery rates of molybdenum, vanadium and nickel in the whole process are all greater than 99%, and the product purity is high, and the quality requirements of the corresponding standards are met.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste treatment, in particular to a method for recovering valuable elements from oil residue discharged from a slurry bed catalyst. Background Art

[0002] Petroleum hydrogenation process is an important means to achieve deep conversion of inferior heavy oil to meet usage requirements. During the heavy oil slurry bed hydrogenation process, about 10% of residual oil will be produced. This part of the oil residue accumulates a large amount of heavy metal elements such as nickel, iron, molybdenum, and vanadium. After deoiling, the valuable heavy metals are highly enriched, and the grade is much higher than that of the original ore. Therefore, recovering valuable metals such as molybdenum, vanadium, and nickel from the oil residue discharged from the slurry bed catalyst is not only conducive to reducing environmental pollution, but also can realize the recycling of valuable metals. Its recovery technology has gradually become an important research topic for industry researchers.

[0003] At present, there are few reports on the recovery of oil residue discharged from slurry bed catalysts. The main existing recovery method is reduction-ammonia leaching. First, vanadium is reduced, and molybdenum is leached through ammonia leaching. Then, vanadium is recovered through oxidation alkali leaching and molybdenum is recovered through acid leaching. This method has low recovery efficiency for molybdenum, vanadium and nickel. It is difficult to reduce vanadium alone, resulting in the dispersion loss of molybdenum. Nickel will also form nickel-ammonia complex ions [Ni(NH3)6] during the ammonia leaching process. 2+ However, dissolution ultimately results in molybdenum, vanadium and nickel products of low purity that do not meet the requirements. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for recovering valuable elements from the oil residue discharged from the slurry bed catalyst. The method of the present invention is used to recover the oil residue discharged from the slurry bed catalyst, and the recovery rate of molybdenum, vanadium and nickel is high and the purity is high.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for recovering valuable elements from oil residue discharged from a slurry bed catalyst, comprising the following steps:

[0007] The oil residue discharged from the slurry bed catalyst is subjected to medium-temperature oxidation roasting and high-temperature cracking in sequence to obtain cracking residue; the oil residue discharged from the slurry bed catalyst is obtained by deoiling the residual oil produced by heavy oil slurry bed hydrogenation; the medium-temperature oxidation roasting is carried out in an air atmosphere at a temperature of 400-800°C; the high-temperature cracking is carried out in a reducing atmosphere at a temperature of 800-1000°C;

[0008] The cracking slag is mixed with an alkaline oxidizing leaching agent for leaching to obtain nickel-containing leaching slag and molybdenum- and vanadium-containing leaching solution; the alkaline oxidizing leaching agent comprises an oxidant, an alkaline leaching agent and water;

[0009] The molybdenum- and vanadium-containing leaching solution is mixed with an ammonium salt to precipitate vanadium, thereby obtaining an ammonium metavanadate product and a vanadium precipitation tail liquid;

[0010] The vanadium precipitation tail liquid is mixed with an acid reagent to neutralize and precipitate molybdenum to obtain crude molybdic acid;

[0011] The crude molybdic acid is sequentially subjected to calcination, alkali dissolution, ion exchange and impurity removal, and neutralization to obtain a molybdic acid product.

[0012] Preferably, the holding time of the medium-temperature oxidation roasting is 1 to 8 hours; and the holding time of the high-temperature cracking is 2 to 5 hours.

[0013] Preferably, the reducing atmosphere comprises one or more of carbon monoxide, natural gas, hydrogen and methane.

[0014] Preferably, the alkaline leaching agent includes one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide, sodium carbonate and sodium bicarbonate; the oxidant includes one or more of sodium hypochlorite, hydrogen peroxide, sodium peroxide, potassium permanganate and potassium dichromate; the mass ratio of the alkaline leaching agent to the oxidant in the cracking slag is 10:(5~8):(1~3); the liquid-solid ratio of the alkaline oxidizing leaching agent to the cracking slag is 3~10mL:1g.

[0015] Preferably, the leaching temperature is 50-90° C. and the leaching time is 1-5 h.

[0016] Preferably, the ammonium salt comprises one or more of ammonium nitrate, ammonium acetate, ammonium chloride, ammonium sulfate, ammonium carbonate and ammonium bicarbonate, and the molar amount of the ammonium salt is 2 to 5 times the molar amount of vanadium element in the molybdenum and vanadium-containing leachate.

[0017] Preferably, the acid reagent includes one or more of sulfuric acid, nitric acid, phosphoric acid, acetic acid, citric acid and hydrochloric acid, the temperature of neutralization and precipitation of molybdenum is 50-70° C., and the precipitation endpoint pH value is 0.5-2.0.

[0018] Preferably, the calcination temperature is 400-550° C., and the holding time is 1-5 hours.

[0019] Preferably, after obtaining the nickel-containing leaching residue, the method further comprises mixing the nickel-containing leaching residue with an acidic leaching agent for leaching to obtain an acid leaching solution and acid leaching residue; and neutralizing the acid leaching solution with alkali to obtain a nickel hydroxide product.

[0020] Preferably, the acidic leaching agent comprises an acid and water, and the acid comprises one or more of sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, citric acid and hydrochloric acid.

[0021] The present invention provides a method for recovering valuable elements from oil residue discharged from a slurry bed catalyst, which has the following beneficial effects compared with the prior art:

[0022] The present invention converts molybdenum, vanadium and nickel into oxides by performing medium-temperature oxidation roasting and high-temperature reduction cracking on the oil residue discharged from the slurry bed catalyst, destroys the bond between the molybdenum and vanadium oxides and the nickel oxide, and then dissolves molybdenum and vanadium by alkaline oxidation leaching, while nickel remains in the residue, thereby realizing efficient separation of molybdenum, vanadium and nickel. After the above treatment, the leaching effect of molybdenum and vanadium is greatly improved, the leaching rate is greater than 99.9%, and more than 99.98% of nickel remains in the residue, which is beneficial to improving the purity of subsequent molybdenum, vanadium and nickel products.

[0023] For the separation and purification of molybdenum and vanadium in the molybdenum- and vanadium-containing leachate, the present invention adopts an ammonium salt precipitation method to selectively separate vanadium, and finally obtains a high-purity ammonium metavanadate product; for the purification of molybdenum in the vanadium precipitation tail liquid, if the traditional acid neutralization method is used to precipitate molybdenum, the vanadium and silicon contents in the obtained molybdenum product exceed the standard, while the present invention calcines the obtained crude molybdic acid after neutralization and precipitation of molybdenum, and performs secondary dissolution, and adopts an ion exchange method to selectively separate vanadium and silicon, and finally obtains a high-purity molybdic acid product with low vanadium and silicon contents.

[0024] The method of the present invention is used to recover the oil residue discharged from the slurry bed catalyst, and the recovery rates of molybdenum, vanadium and nickel are high, and the product purity is high. The comprehensive recovery rates of molybdenum, vanadium and nickel in the whole process are all greater than 99%, which is more than 5% higher than the existing technology; the purity of the ammonium metavanadate product is higher than 99wt%, and the vanadium and silicon content of the molybdic acid product is less than 0.01wt%, and the purity is higher than 99.95wt%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a schematic diagram of a process for recovering valuable elements from oil residue discharged from a slurry bed catalyst according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention provides a method for recovering valuable elements from oil residue discharged from a slurry bed catalyst, comprising the following steps:

[0027] The oil residue discharged from the slurry bed catalyst is subjected to medium-temperature oxidation roasting and high-temperature cracking in sequence to obtain cracking residue; the oil residue discharged from the slurry bed catalyst is obtained by deoiling the residual oil produced by heavy oil slurry bed hydrogenation; the medium-temperature oxidation roasting is carried out in an air atmosphere at a temperature of 400-800°C; the high-temperature cracking is carried out in a reducing atmosphere at a temperature of 800-1000°C;

[0028] The cracking slag is mixed with an alkaline oxidizing leaching agent for leaching to obtain nickel-containing leaching slag and molybdenum- and vanadium-containing leaching solution; the alkaline oxidizing leaching agent comprises an oxidant, an alkaline leaching agent and water;

[0029] The molybdenum- and vanadium-containing leaching solution is mixed with an ammonium salt to precipitate vanadium, thereby obtaining an ammonium metavanadate product and a vanadium precipitation tail liquid;

[0030] The vanadium precipitation tail liquid is mixed with an acid reagent to neutralize and precipitate molybdenum to obtain crude molybdic acid;

[0031] The crude molybdic acid is sequentially subjected to calcination, alkali dissolution, ion exchange and neutralization to obtain a molybdic acid product.

[0032] Figure 1 The schematic diagram of the process of recovering valuable elements from the oil residue discharged from the slurry bed catalyst according to the embodiment of the present invention is as follows. Figure 1 Provide detailed explanation.

[0033] In the present invention, unless otherwise specified, the raw materials involved are commercially available products well known in the art.

[0034] The present invention sequentially performs medium-temperature oxidation roasting and high-temperature cracking on the oil residue discharged from the slurry bed catalyst to obtain cracking residue. In the present invention, the oil residue discharged from the slurry bed catalyst is obtained by deoiling the residual oil produced by heavy oil slurry bed hydrogenation.

[0035] In the present invention, the medium-temperature oxidation roasting is carried out in an air atmosphere, the temperature of the medium-temperature oxidation roasting is 400-800°C, and can be 400, 500, 600, 650, 700 or 800°C, and the holding time is preferably 1-8h, and can be 1, 2, 3, 4, 5, 6, 7 or 8h. The present invention achieves deoiling and decarbonization through the medium-temperature oxidation roasting, and converts molybdenum, vanadium and nickel into high-valent oxides.

[0036] In the present invention, the high temperature cracking is carried out in a reducing atmosphere (i.e., high temperature reduction cracking), and the reducing atmosphere preferably includes one or more of carbon monoxide, natural gas, hydrogen and methane; the temperature of the high temperature cracking is 800-1000°C, which can be 800, 900, 960 or 1000°C, and the holding time is preferably 2-5h, which can be 2, 3, 4 or 5h. The present invention reduces the high-valent molybdenum and vanadium in the roasted product into low-valent oxide forms in a reducing atmosphere, which is conducive to destroying the chemical bonds between molybdenum, vanadium and nickel oxides, weakening the binding force of nickel oxides to molybdenum and vanadium, and as the cracking time increases, the degree of breakage of the raw material molecules gradually deepens, so that the nickel oxide no longer binds to molybdenum and vanadium, thereby greatly improving the subsequent leaching rate of molybdenum and vanadium.

[0037] After obtaining the cracking slag, the present invention mixes the cracking slag with an alkaline oxidizing leaching agent for leaching to obtain nickel-containing leaching slag (also referred to as nickel-containing slag in the embodiment) and molybdenum- and vanadium-containing leaching solution (also referred to as molybdenum- and vanadium-containing solution in the embodiment). In the present invention, the alkaline oxidizing leaching agent comprises an oxidant, an alkaline leaching agent and water, and the oxidant, the alkaline leaching agent and water are mixed with the cracking slag.

[0038] In the present invention, the alkaline leaching agent preferably includes one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide, sodium carbonate and sodium bicarbonate; the oxidant preferably includes one or more of sodium hypochlorite, hydrogen peroxide, sodium peroxide, potassium permanganate and potassium dichromate. In the present invention, the mass ratio of the alkaline leaching agent to the oxidant in the cracking slag and the alkaline oxidizing leaching agent is preferably 10:(5-8):(1-3), more preferably 10:(5-7):(2-3); the liquid-solid ratio of the alkaline oxidizing leaching agent to the cracking slag is preferably 3-10 mL:1 g, more preferably 4-7 mL:1 g.

[0039] In the present invention, the leaching temperature is preferably 50-90°C, and can be 50, 60, 65, 70, 80, 85 or 90°C, and the time is preferably 1-5 hours, and more preferably 1, 2, 3, 4 or 5 hours. During the leaching process, molybdenum and vanadium are oxidized to the highest valence and dissolved again, while nickel insoluble in alkaline solution remains in the slag, and nickel-containing leaching slag and molybdenum- and vanadium-containing leaching solution are obtained by filtration.

[0040] After obtaining the molybdenum and vanadium-containing leachate, the present invention mixes the molybdenum and vanadium-containing leachate with an ammonium salt to precipitate vanadium, and obtains an ammonium metavanadate product and a vanadium precipitation tail liquid. In the present invention, the ammonium salt preferably includes one or more of ammonium nitrate, ammonium acetate, ammonium chloride, ammonium sulfate, ammonium carbonate and ammonium bicarbonate, and the molar amount of the ammonium salt is preferably 2 to 5 times the molar amount of the vanadium element in the molybdenum and vanadium-containing leachate. After the vanadium precipitation, the vanadium precipitation tail liquid and the solid phase product are obtained by filtration; the solid phase product is washed to obtain a white ammonium metavanadate product, and the washing preferably uses an aqueous solution of the above-mentioned ammonium salt, and the mass fraction of the aqueous solution of the ammonium salt is preferably 5%, and the number of washings is preferably 5 times. In the present invention, the purity of the ammonium metavanadate product is preferably greater than 99wt%.

[0041] After obtaining the vanadium precipitation tail liquid, the present invention mixes the vanadium precipitation tail liquid with an acid reagent to neutralize and precipitate molybdenum to obtain crude molybdic acid. In the present invention, the acid reagent preferably includes one or more of sulfuric acid, nitric acid, phosphoric acid, acetic acid, citric acid and hydrochloric acid, the temperature of neutralizing and precipitating molybdenum is preferably 50-70°C, and can be 50, 60, 65 or 70°C, and the precipitation endpoint pH value is preferably 0.5-2.0, more preferably 0.9-1.4. After the neutralization and precipitation of molybdenum, crude molybdic acid is obtained by filtration.

[0042] After obtaining the crude molybdic acid, the present invention sequentially calcines, dissolves with alkali, removes impurities by ion exchange and neutralizes the crude molybdic acid to obtain a molybdic acid product. In the present invention, the calcination temperature is preferably 400-550° C., and may be 400, 450, 500 or 550° C., and the holding time is preferably 1-5 hours, and may be 1, 2, 3, 4 or 5 hours. After the calcination, crude molybdenum trioxide is obtained.

[0043] In the present invention, the alkaline reagent used in the alkaline dissolution is preferably a sodium hydroxide solution. After the alkaline dissolution, a crude sodium molybdate solution is obtained. The pH value of the crude sodium molybdate solution is preferably 6.0-8.0, and more preferably 6.5-7.5.

[0044] In the present invention, the ion exchange preferably uses an anion exchange resin, and the anion exchange resin is selected to have a selective adsorption effect on anions such as vanadium and silicon, and the adsorption rate of molybdenum is less than 1%. In the present invention, the specific operation of the ion exchange is preferably: the crude sodium molybdate solution flows through an exchange column equipped with an anion exchange resin, with 3 to 5 adsorption stages, to obtain a resin loaded with vanadium and silicon and a pure sodium molybdate solution; the resin loaded with vanadium and silicon is preferably desorbed with 3BV of sodium hydroxide solution (5wt%), and then regenerated with 3BV of sulfuric acid solution (5wt%), and the flow rate throughout the process is 2 to 10BV / h.

[0045] In the present invention, the neutralization preferably uses an acid reagent to neutralize the pure sodium molybdate solution, and the acid reagent preferably includes one or more of sulfuric acid, nitric acid, phosphoric acid, acetic acid, citric acid and hydrochloric acid, and the neutralization endpoint pH value is preferably 0.5~1.5, more preferably 0.5~0.8. After the neutralization, the molybdic acid product is precipitated; the molybdic acid product is dehydrated to obtain a pure molybdic acid product, and the temperature of the dehydration is preferably 50~80°C, and the time is preferably 12h. In the present invention, the vanadium and silicon content of the pure molybdic acid product is below 0.01wt%, and the purity of molybdic acid is higher than 99.95wt%.

[0046] After obtaining the nickel-containing leaching residue, the present invention preferably further comprises mixing the nickel-containing leaching residue and an acidic leaching agent for leaching to obtain an acid leaching solution and an acid leaching residue; and neutralizing the acid leaching solution with alkali to obtain a nickel hydroxide product. In the present invention, the acidic leaching agent preferably comprises acid and water, and the acid preferably comprises one or more of sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, citric acid and hydrochloric acid, more preferably sulfuric acid, nitric acid, phosphoric acid or hydrochloric acid, and the mass fractions of sulfuric acid, nitric acid, phosphoric acid and hydrochloric acid are preferably 95%, 68%, 99% and 36-38%, respectively. In the present invention, the mass of the acid in the acidic leaching agent is preferably 1-2 times the mass of the nickel-containing slag, and the liquid-solid ratio of the acidic leaching agent to the nickel-containing leaching residue is preferably 5mL:1g; the leaching temperature is preferably 60-80°C, more preferably 72-75°C, and the time is preferably 1h. After the leaching, filter to obtain an acid leaching solution and an acid leaching residue, and the acid leaching residue mainly contains Al, Si, Mo, Fe and Ni. In the present invention, the alkaline reagent used for the alkali neutralization is preferably sodium hydroxide, and the endpoint pH value of the alkali neutralization is preferably 7-9, more preferably 7-8; after the alkali neutralization, the nickel hydroxide product is precipitated. In the present invention, the purity of the nickel hydroxide product is greater than 98wt%.

[0047] In order to further illustrate the present invention, the method for recovering valuable elements from oil residue discharged from a slurry bed catalyst provided by the present invention is described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0048] In each embodiment, the oil residue discharged from the slurry bed catalyst is obtained by deoiling the residual oil produced by heavy oil slurry bed hydrogenation.

[0049] Example 1

[0050] Recovering valuable elements from the oil residue discharged from the slurry bed catalyst, the process is as follows Figure 1 As shown, the steps are as follows:

[0051] Step (A1): 1000 g of the discharged oil residue is placed in an air atmosphere at 400° C. for oxidative roasting for 8 h, and then cracked in a hydrogen atmosphere at 1000° C. for 2 h. After the reaction is completed, 128.52 g of cracked residue is obtained, and the cracked residue contains 31.88 wt% of molybdenum, 17.52 wt% of vanadium, and 4.95 wt% of nickel;

[0052] Step (B1): 128.52 g of the cracking slag obtained in step (A1), 77 g of sodium hydroxide, 26 g of potassium dichromate and water are mixed for leaching at a leaching temperature of 65° C., a leaching time of 3 h, a liquid-to-solid ratio of 7 mL:1 g, and a molybdenum- and vanadium-containing solution containing 45.48 g / L of molybdenum, 24.97 g / L of vanadium and 0.001 g / L of nickel is obtained by filtration, as well as 26.83 g of nickel-containing slag containing 23.71 wt% of nickel;

[0053] Step (C1): adding 160 g of ammonium sulfate to the molybdenum and vanadium-containing solution obtained in step (B1), filtering after the reaction to obtain white ammonium metavanadate and vanadium precipitation tail liquid, washing the ammonium metavanadate with 5 wt% ammonium sulfate solution 5 times, and the obtained ammonium metavanadate product has a purity of 99.4 wt%;

[0054] Step (D1): neutralizing the vanadium precipitation tail liquid obtained in step (C1) with phosphoric acid at 50°C to obtain a precipitation, the end point pH value is 1.4, filtering to obtain crude molybdic acid, and then calcining in a muffle furnace at 450°C for 3h to obtain crude molybdenum trioxide;

[0055] Step (E1): dissolving the crude molybdenum trioxide obtained in step (D1) with sodium hydroxide solution to obtain a crude sodium molybdate solution with a pH of 6.5, containing 69.57 g / L of molybdenum, 0.28 g / L of vanadium, and 0.3 g / L of silicon; removing vanadium and silicon by three-stage adsorption at a flow rate of 5 BV / h through an anion exchange resin (AP500FR vanadium-molybdenum separation resin) to obtain a pure sodium molybdate solution, containing 69.49 g / L of molybdenum, 0.005 g / L of vanadium, and 0.005 g / L of silicon; neutralizing the pure sodium molybdate solution with nitric acid, the end point pH value is 0.8, and the obtained pure molybdic acid is dried at 80°C for 12h to remove free water, the contents of vanadium and silicon in the pure molybdic acid are 0.01wt% and 0.003wt%, respectively, and the total amount of impurity elements is 0.3wt%;

[0056] Step (F1): the nickel-containing slag obtained in step (B1), 50 g of hydrochloric acid (36-38 wt%) and water are mixed for leaching at a leaching temperature of 75° C., a leaching time of 1 h, a liquid-to-solid ratio of 5 mL:1 g, and an acid leaching solution containing 47.18 g / L of nickel is obtained by filtration;

[0057] Step (G1): The acid leaching solution obtained in step (F1) is neutralized with sodium hydroxide to a pH value of 9 to obtain a nickel hydroxide product with a purity of 98.2 wt%.

[0058] During the cracking slag leaching process, the molybdenum leaching rate is 99.90%, and the vanadium leaching rate is 99.81%; the comprehensive molybdenum recovery rate of the whole process is 99.4%, the comprehensive vanadium recovery rate is 99.3%, and the comprehensive nickel recovery rate is 99.5%.

[0059] Example 2

[0060] Recovering valuable elements from the oil residue discharged from the slurry bed catalyst, the process is as follows Figure 1 As shown, the steps are as follows:

[0061] Step (A2): 1000 g of the discharged oil residue was placed in an air atmosphere at 700° C. for oxidative roasting for 6 h, and then cracked in a carbon monoxide atmosphere at 960° C. for 5 h. After the reaction, 125.26 g of cracked slag was obtained, which contained 32.10 wt% of molybdenum, 17.68 wt% of vanadium, and 5.05 wt% of nickel;

[0062] Step (B2): 125.26 g of the cracking slag obtained in step (A2), 65 g of sodium carbonate, 35 g of hydrogen peroxide and water are mixed for leaching at a leaching temperature of 85° C., a leaching time of 2 h, a liquid-to-solid ratio of 5 mL:1 g, and a molybdenum- and vanadium-containing solution containing 64.10 g / L of molybdenum, 35.27 g / L of vanadium and 0.001 g / L of nickel is obtained by filtration, as well as 28.81 g of nickel-containing slag containing 21.95 wt% of nickel;

[0063] Step (C2): adding 112 g of ammonium acetate to the molybdenum and vanadium-containing solution obtained in step (B2), filtering after the reaction to obtain white ammonium metavanadate and vanadium precipitation tail liquid, washing the ammonium metavanadate with 5 wt% ammonium acetate solution 5 times, and the obtained ammonium metavanadate product has a purity of 99.1 wt%;

[0064] Step (D2): neutralizing the vanadium precipitation tail liquid obtained in step (C2) with hydrochloric acid at 60°C to obtain a precipitation, the end point pH value is 1.1, filtering to obtain crude molybdic acid, and then calcining in a muffle furnace at 400°C for 3h to obtain crude molybdenum trioxide;

[0065] Step (E2): dissolving the crude molybdenum trioxide obtained in step (D2) with sodium hydroxide solution to obtain a crude sodium molybdate solution with a pH of 7.5, containing 73.57 g / L of molybdenum, 0.42 g / L of vanadium, and 0.22 g / L of silicon; removing vanadium by 5-stage adsorption at a flow rate of 3 BV / h through an anion exchange resin (AP500FR vanadium-molybdenum separation resin) to obtain a pure sodium molybdate solution, containing 73.48 g / L of molybdenum, 0.003 g / L of vanadium, and 0.005 g / L of silicon; neutralizing the pure sodium molybdate solution with citric acid, the end point pH value is 0.5, and the obtained pure molybdenum acid is dried at 50° C. for 12 hours to remove free water, and the contents of vanadium and silicon in the pure molybdenum acid are 0.008wt% and 0.001wt%, respectively, and the total amount of impurity elements is 0.4wt%;

[0066] Step (F2): leaching the nickel-containing slag obtained in step (B2), 40 g of sulfuric acid (95 wt%) and water at a leaching temperature of 60° C., a leaching time of 1 h, a liquid-to-solid ratio of 5 mL:1 g, and filtering to obtain an acid leaching solution containing 43.65 g / L of nickel;

[0067] Step (G2): The acid leaching solution obtained in step (F2) is neutralized with sodium hydroxide to a pH value of 7 to obtain nickel hydroxide with a purity of 98.3 wt%.

[0068] During the cracking slag leaching process, the molybdenum leaching rate is 99.85%, and the vanadium leaching rate is 99.75%; the comprehensive molybdenum recovery rate of the whole process is 99.3%, the comprehensive vanadium recovery rate is 99.1%, and the comprehensive nickel recovery rate is 99.2%.

[0069] Example 3

[0070] Recovering valuable elements from the oil residue discharged from the slurry bed catalyst, the process is as follows Figure 1 As shown, the steps are as follows:

[0071] Step (A3): 1000 g of the discharged oil residue was placed in an air atmosphere at 800° C. for oxidative roasting for 1 h, and then cracked in a methane atmosphere at 900° C. for 3 h. After the reaction was completed, 120.23 g of cracked slag was obtained, which contained 33.01 wt% of molybdenum, 18.15 wt% of vanadium, and 5.21 wt% of nickel;

[0072] Step (B3): 120.23 g of the cracking slag obtained in step (A3), 90 g of potassium hydroxide, 33 g of sodium hypochlorite and water are mixed for a stage of leaching, the leaching temperature is 90 ° C, the leaching time is 1 h, the liquid-solid ratio is 4 mL: 1 g, and a molybdenum- and vanadium-containing solution containing 82.42 g / L of molybdenum, 45.31 g / L of vanadium, and 0.001 g / L of nickel is obtained by filtration, and 29.21 g of nickel-containing slag containing 21.44 wt% of nickel is obtained;

[0073] Step (C3): Add 70g of ammonium chloride to the molybdenum and vanadium-containing solution obtained in step (B3), filter after the reaction to obtain white ammonium metavanadate and vanadium precipitation tail liquid, wash the ammonium metavanadate with 5wt% ammonium chloride solution 5 times, and the purity of the obtained ammonium metavanadate product is 99.3wt%;

[0074] Step (D3): neutralize the vanadium precipitation tail liquid obtained in step (C3) with acetic acid at 65°C to obtain a precipitation, and the end point pH value is 0.9. Filter to obtain crude molybdic acid, and then place it in a muffle furnace and roast it at 550°C for 3h to obtain crude molybdenum trioxide;

[0075] Step (E3): dissolving the crude molybdenum trioxide obtained in step (D3) with sodium hydroxide solution to obtain a crude sodium molybdate solution with a pH of 8.0, containing 76.27 g / L of molybdenum, 0.41 g / L of vanadium, and 0.21 g / L of silicon; removing vanadium by 5-stage adsorption at a flow rate of 8 BV / h through an anion exchange resin (AP500FR vanadium-molybdenum separation resin) to obtain a pure sodium molybdate solution, containing 76.22 g / L of molybdenum, 0.002 g / L of vanadium, and 0.005 g / L of silicon; neutralizing the pure sodium molybdate solution with hydrochloric acid, the end point pH value is 0.5, and the obtained pure molybdic acid is dried at 68°C for 12 hours to remove free water, and the contents of vanadium and silicon in the pure molybdic acid are 0.007wt% and 0.004wt%, respectively, and the total amount of impurity elements is 0.2wt%;

[0076] Step (F3): the nickel-containing slag obtained in step (B3), 60 g of phosphoric acid (99 wt%) and water are mixed for leaching at a leaching temperature of 72° C., a leaching time of 1 h, a liquid-to-solid ratio of 5 mL:1 g, and an acid leaching solution containing 42.67 g / L of nickel is obtained by filtration;

[0077] Step (G3): The acid leaching solution obtained in step (F3) is neutralized with a sodium hydroxide solution to a pH value of 7.8 to obtain a nickel hydroxide product with a purity of 98.6 wt%.

[0078] During the cracking slag leaching process, the molybdenum leaching rate is 99.90%, and the vanadium leaching rate is 99.81%; the comprehensive molybdenum recovery rate of the whole process is 99.4%, the comprehensive vanadium recovery rate is 99.4%, and the comprehensive nickel recovery rate is 99.3%.

[0079] The embodiment of the present invention pre-treats the oil residue discharged from the slurry bed catalyst through a first stage of medium-temperature oxidation roasting-a second stage of high-temperature reduction cracking. The first stage of medium-temperature oxidation roasting realizes deoiling and decarbonization, and converts molybdenum, vanadium, and nickel into high-valent oxides. The purpose of the second stage of high-temperature reduction cracking is to reduce the high-valent molybdenum and vanadium in the roasting product into low-valent oxide forms in a reducing atmosphere, and destroy the chemical bonds between low-valent molybdenum, vanadium oxides and nickel oxides through high-temperature cracking, so that the raw material molecules are broken, thereby making full preparations for the subsequent efficient leaching of molybdenum and vanadium and the separation of nickel. The subsequent cracking slag is subjected to alkaline leaching under the action of an oxidant, and molybdenum and vanadium are oxidized to the highest valence and dissolved again, while the nickel insoluble in the alkaline solution remains in the slag, and the leaching rates of molybdenum and vanadium are both greater than 99.9%. The comprehensive recovery rates of molybdenum, vanadium, and nickel in the whole process are all greater than 99%, and the obtained ammonium metavanadate product meets the chemical industry standards, the nickel hydroxide product meets the national standards, and the molybdenum acid product meets the industrial grade standards.

[0080] With respect to the oxidative roasting and high-temperature cracking process in the first step of the above technical scheme and the oxidative leaching process in the second step, the inventors explored the conditions of medium-temperature oxidative roasting of 200g of discharged oil residue in an air atmosphere at 650°C for 5h, high-temperature reduction cracking temperature of 1000°C, reducing atmosphere of carbon monoxide, leaching reagent sodium hydroxide dosage of 16g, oxidant sodium hypochlorite dosage of 5g, leaching temperature of 80°C, leaching time of 3h, liquid-solid ratio of 5mL:1g, changing the high-temperature cracking time, and obtaining the relationship data between the leaching efficiency of molybdenum and vanadium and the high-temperature cracking time, as shown in Table 1.

[0081] Table 1 Relationship between leaching efficiency of molybdenum and vanadium and high temperature cracking time

[0082]

[0083] As can be seen from Table 1, adding a high-temperature reduction cracking process after medium-temperature oxidative roasting can greatly improve the subsequent leaching rate of molybdenum and vanadium, indicating that high-temperature cracking under a reducing atmosphere is conducive to destroying the chemical bonds between molybdenum, vanadium and nickel oxides, and weakening the binding force of nickel oxide to molybdenum and vanadium; with the extension of cracking time, the degree of breakage of the raw material molecules gradually deepens, so that the nickel oxide no longer binds to molybdenum and vanadium, thereby increasing the leaching rate of molybdenum and vanadium, achieving efficient leaching of molybdenum and vanadium, while the nickel that is insoluble in alkaline solution remains in the slag, achieving efficient separation of molybdenum, vanadium and nickel.

[0084] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for recovering valuable elements from oil residue discharged from a slurry bed catalyst, characterized in that: The following steps are involved: The oil residue discharged from the slurry bed catalyst is subjected to medium-temperature oxidation roasting and high-temperature cracking in sequence to obtain cracking residue; the oil residue discharged from the slurry bed catalyst is obtained by deoiling the residual oil produced by heavy oil slurry bed hydrogenation; the medium-temperature oxidation roasting is carried out in an air atmosphere at a temperature of 500-800°C; the high-temperature cracking is carried out in a reducing atmosphere at a temperature of 800-1000°C; The cracking slag is mixed with an alkaline oxidizing leaching agent for leaching to obtain nickel-containing leaching slag and molybdenum- and vanadium-containing leaching solution; the alkaline oxidizing leaching agent comprises an oxidant, an alkaline leaching agent and water; the leaching temperature is 50-90° C. and the leaching time is 1-5 hours; The molybdenum- and vanadium-containing leaching solution is mixed with an ammonium salt to precipitate vanadium, thereby obtaining an ammonium metavanadate product and a vanadium precipitation tail liquid; The vanadium precipitation tail liquid is mixed with an acid reagent to neutralize and precipitate molybdenum to obtain crude molybdic acid; The crude molybdic acid is sequentially subjected to calcination, alkali dissolution, ion exchange and impurity removal, and neutralization to obtain a molybdic acid product.

2. The method according to claim 1, characterized in that The holding time of the medium-temperature oxidation roasting is 1 to 8 hours; the holding time of the high-temperature cracking is 2 to 5 hours.

3. The method according to claim 1, characterized in that The reducing atmosphere includes one or more of carbon monoxide, natural gas, hydrogen and methane.

4. The method according to claim 1, characterized in that: The alkaline leaching agent includes one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide, sodium carbonate and sodium bicarbonate; the oxidant includes one or more of sodium hypochlorite, hydrogen peroxide, sodium peroxide, potassium permanganate and potassium dichromate; the mass ratio of the alkaline leaching agent to the oxidant in the cracking slag is 10:(5~8):(1~3); the liquid-solid ratio of the alkaline oxidizing leaching agent to the cracking slag is 3~10mL:1g.

5. The method according to claim 1, characterized in that The ammonium salt includes one or more of ammonium nitrate, ammonium acetate, ammonium chloride, ammonium sulfate, ammonium carbonate and ammonium bicarbonate, and the molar amount of the ammonium salt is 2 to 5 times the molar amount of the vanadium element in the molybdenum- and vanadium-containing leaching solution.

6. The method according to claim 1, characterized in that The acid reagent includes one or more of sulfuric acid, nitric acid, phosphoric acid, acetic acid, citric acid and hydrochloric acid. The temperature of neutralization and precipitation of molybdenum is 50-70° C., and the precipitation endpoint pH value is 0.5-2.

0.

7. The method according to claim 1, characterized in that The calcination temperature is 400-550° C., and the heat preservation time is 1-5 hours.

8. The method according to claim 1, characterized in that After obtaining the nickel-containing leaching residue, the method further comprises mixing the nickel-containing leaching residue with an acidic leaching agent for leaching to obtain an acid leaching solution and acid leaching residue; and neutralizing the acid leaching solution with alkali to obtain a nickel hydroxide product.

9. The method according to claim 8, characterized in that The acidic leaching agent includes acid and water, and the acid includes one or more of sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, citric acid and hydrochloric acid.

Images