CN111876603A - Wet process for recovering Fe, Al, Ni, Mo and Co from waste hydrorefining catalyst - Google Patents

Abstract

The invention discloses a process for wet recovery of iron, aluminum, nickel, molybdenum and cobalt from hydrorefining waste catalysts. After the catalyst is calcined and ground, a froth flotation method is used for rough separation, and the roughened catalyst is treated with dilute sulfuric acid. Impregnation, filtration, molybdenum-containing filter residue enters the next process, the filtrate is precipitated step by step to separate iron and aluminum, and then the filtered solution is electrolyzed with anion exchange resin and electrolytic cell, and the cathode of the electrolytic cell can recover high-purity nickel With cobalt metal, sulfuric acid solution is recovered anode under the action of anion exchange resin. The molybdenum-containing filter residue is dissolved in the recovered sulfuric acid for electrolysis, the cathode can obtain high-purity molybdenum metal, and the anode can recover sulfuric acid solution under the action of anion exchange resin. The recovery of the catalyst is not only efficient, but also has no waste liquid discharge, sulfuric acid can be recycled without introducing other elements, and has the advantages of simple and efficient process, high economic value, high atom utilization rate, and no impact on the environment.

Description

Process for wet recovery of iron, aluminum, nickel, molybdenum and cobalt from spent hydrofinishing catalysts

technical field

The present invention relates to the technical field of catalyst recovery. It relates to a process for wet recovery of iron, aluminum, nickel, molybdenum and cobalt from hydrorefining waste catalysts, in particular to a method for wet recovery of iron, aluminum, nickel, molybdenum and cobalt from nickel-containing molybdenum catalysts, the method The recovery rate is higher.

Background technique

Due to the rapid development of science and technology, economic development is largely at the expense of natural resources and ecological environment. Almost 80% of the chemical reactions in the chemical and petroleum industries, which have grown rapidly since the last century, require catalysts. Thousands of tons of spent catalysts containing molybdenum alone are discharged from the device every year, so the recovery and utilization of valuable metals in spent catalysts has attracted much attention.

As an alloying additive of iron, molybdenum helps to form a completely pearlite matrix, which can improve the strength and toughness of cast iron, improve the uniformity of the structure of large castings, and also improve the hardenability of heat-treated castings. Molybdenum-containing gray cast iron has good wear resistance and can be used as brake wheels and brake pads for heavy vehicles. And molybdenum is one of the necessary "trace elements" in plants, accounting for about 0.5ppm of plant dry matter, which is indispensable and irreplaceable. In recent years, ammonium molybdate has been widely used as a trace element fertilizer at home and abroad, which can significantly improve the quality and yield of legumes, forages and other crops. Molybdenum can also accelerate the formation and transformation of carbohydrates in plants, increase the content and stability of plant chlorophyll, and increase the content of vitamin C. Molybdenum, nickel, cobalt, etc. can manufacture different types of stainless steel, tool steel, high-speed steel and alloy steel. The stainless steel made has good corrosion resistance and can be used for corrosion-resistant steel pipes for oil exploration. A stainless steel with about 6% molybdenum can also replace titanium for seawater desalination devices, ocean-going ships, and offshore oil and natural gas exploration pipelines. This type of stainless steel can also be used in automobile casings, sewage treatment equipment, etc.

The catalyst will be gradually poisoned during use, and will eventually lose its catalytic activity and be scrapped. According to Liu Gongzhao et al., the annual consumption of catalysts in the world is about 800,000 tons, and my country is 70,000 tons. There are many kinds of molybdenum-containing waste catalysts, and the molybdenum content ranges from 3% to 20%. If the cobalt and molybdenum are not recycled and regenerated, the total amount of cobalt and molybdenum lost will be very surprising. Therefore, the recovery of molybdenum, cobalt and other metals from molybdenum-containing waste catalysts is not only conducive to the sustainable development of the cobalt and molybdenum industries, but also a concrete manifestation of the concept of turning waste into treasure and practicing circular economy, which has significant ecological benefits, economic and social benefits.

There are three main types of catalyst recovery schemes:

Acid leaching method: The acid leaching method uses common sulfuric acid, hydrochloric acid or nitric acid as the leaching agent. The main principle is to dissolve the molybdenum and other soluble impurities in the spent catalyst together in the acid, and then add reagents, extraction, precipitation, etc. The method achieves impurity removal and separate recovery of molybdenum and other metals.

Alkaline leaching method: The main principle of the alkali leaching method is to make molybdenum in the form of sulfide (MoS ₂ ) in the spent catalyst to be converted into molybdenum oxide (MoO ₃ ) by roasting, and then use alkali as a leaching agent to convert molybdenum oxide. It is a soluble compound, and then metals such as molybdenum are separated and recovered by operations such as acid adjustment, impurity removal, and extraction.

Fire recovery:

There are not many domestic researches on the recovery of molybdenum from waste catalysts by pyrotechnics. The main reason is that the waste catalysts are smelted by plasma furnaces, and the separation effect of slag and iron is good. After enrichment, valuable metals in the alloy account for about 70%, and the average recovery rate of metals reaches 93%, which can greatly reduce the load of separation and purification of valuable metals by hydrometallurgical technology. However, this process has obvious shortcomings such as high energy consumption and immature process, which needs to be further improved. Although the above three schemes are all feasible, the disadvantages are also very prominent, and the recovery rate is low.

In "CN202010139641.0 A method for recovering molybdenum from molybdenum-containing waste catalyst" and "Research on the extraction and separation of molybdenum, vanadium, nickel and cobalt in acid solution, Zeng Li", etc., are all recovered from acid leaching by adding extractant Molybdenum is recovered by liquid extraction. This method not only has high production cost, but also has a relatively large impact on the environment when the extraction agent is used. In "Experimental Research on Comprehensive Recovery of Molybdenum, Nickel, Bi and Cobalt Waste Catalysts, Ma Chengbing", "CN201610631967.9 Process for Recovering Molybdenum, Bi, Cobalt, and Nickel from Waste Catalysts" by adjusting the pH value, the different catalysts are precipitated step by step. For metal salts, this method has a low recovery rate and low purity, and has a relatively large adverse impact on the environment. Moreover, in many current recovery and separation processes of molybdenum-containing catalysts, most of them only consider the single recovery of molybdenum metal, and there are no specific separation requirements for other metal components. There are more factors that need to be considered, and the difficulty will be greater. In addition, in the existing recovery reactions, the batch reaction process is adopted, that is, a large amount of acid waste liquid will be discharged each time the catalyst is recovered. These waste liquids need to be discharged or reused after special treatment. The production is not only harmful to the environment and the treatment cost is high, but also there may be insufficiently recovered metals in the discharged acid waste liquid, which is obviously not conducive to the full recovery of the various metal components of the molybdenum-containing waste catalyst.

Therefore, how to fully recover the iron, aluminum, nickel, molybdenum and cobalt metals in the nickel-molybdenum catalyst, and also effectively improve the common waste liquid treatment problem of catalyst recovery, is one of the technical problems to be solved by the present invention.

SUMMARY OF THE INVENTION

In order to solve the technical problems in the background art, the present invention provides a continuous recovery nickel-molybdenum catalyst system, in which not only the catalyst components of iron, aluminum, nickel, molybdenum and cobalt can be recovered separately, but the recovery of each metal can be reached more than 95%. At the same time, the by-product sulfuric acid solution can be continuously recycled in the system, which solves the problem that the traditional batch reaction acid waste liquid is difficult to directly reuse.

In order to achieve the above-mentioned technical purpose, the present invention adopts the following technical solutions:

(1) The waste nickel-molybdenum catalyst is calcined, and after cooling, the catalyst is pulverized into powder, which is subjected to rough selection by the foam flotation method, and then defoamed.

Further, the particles pulverized by the catalyst are between 180 and 1800 mesh, and it is further optimized that the particles pulverized by the catalyst are between 1000 and 1600 mesh.

Further, the foaming agent used is fatty alcohol, and the foam flotation method adopts centrifugal defoaming, and the centrifugal speed is further optimized to be 600-800 rpm.

(2) put the catalyst after rough selection into dilute sulfuric acid, filter, collect filtrate and filter residue respectively, wherein filter residue is standby, adjust filtrate pH value, settle step by step, recover iron, aluminum metal respectively.

Further, the temperature during acid leaching is 40-90 ℃, the concentration of dilute sulfuric acid is 2-4 mol/L, and the acid leaching time is 1-3 hours; The concentration is 3-4 mol/L, and the time is 1-2 hours.

Further, adjusting pH=1.5-3.5 to recover iron metal, adjusting pH=3.5-5.5 to recover iron metal; further optimized to pH=2-3 for iron and pH=4-5 for aluminum.

(3) adjust the pH value of the catalyst acid solution after reclaiming iron and aluminum metal, place in the electrolytic cell after adjustment and carry out electrolysis again, reclaim nickel, cobalt metal, and can obtain high-concentration sulfuric acid solution simultaneously after the recovery;

Further, the pH value was adjusted to 2-3.

Further, the electrolysis is to pass the filtered catalyst acid solution into the electrolytic cell, and the applied voltage is Ni=2～20V during the recovery of nickel metal, and the voltage is adjusted to recover 20～50V after recovery to recover Co; it is further optimized as Ni=10～20V ; Co=30～40V.

The electrolytic cell is composed of a cathode, an anode and an anion exchange resin membrane; the recovered metal element is used as the cathode, the graphite is used as the anode, and the anion exchange resin is a sulfate anion exchange resin.

And in the above steps, after the electrolysis reaction is completed, a high-concentration sulfuric acid solution can also be obtained in the cathode chamber, which is used for the next reaction.

Further, the concentration of the sulfuric acid solution on the side of the semipermeable membrane (anion exchange resin) near the cathode is 2 to 8 mol/L. The optimization is that the concentration of sulfuric acid solution on the side of the semipermeable membrane near the cathode is 3-4 mol/L.

(4) adding the standby filter residue of step (2) to the sulfuric acid obtained in step (3) and adjusting to a specific concentration for acid leaching, acid leaching for a period of time and filtering, then adjusting the pH value of the filtrate, adding NH ₄ F and HF solution, then placing Electrolysis is carried out in an electrolytic cell, and molybdenum metal is recovered by electrolysis, and at the same time, a by-product sulfuric acid solution is obtained, which is directly used in the next step to carry out a cyclic reaction.

Among them, the concentration of acid leaching sulfuric acid is 6～10mol/L, the acid leaching temperature is 40～60℃, and the acid leaching time is 1～3 hours. Further optimization is that the concentration of sulfuric acid is 8-9 mol/L, the acid leaching temperature is 50-60 °C, and the acid leaching time is 1-2 hours.

Further, in step (4), NH ₄ F and HF are added until the concentration in the filtrate reaches 1-5 g/L, and the voltage of electrolytic Mo is 30-60V. Further optimization is that the concentration of NH ₄ F and HF in the filtrate is 3-4 g/L, and Mo=40-50V.

The advantages of the catalyst recovery process of the present invention are as follows:

The invention provides a cyclic treatment system for sustainable treatment of large quantities of catalysts. In the system, under the premise of introducing as few ions as possible, not only the recovery rate of aluminum, nickel, molybdenum and cobalt can be improved, but also the For the first time, anion exchange resin was introduced in catalyst recovery, which can realize the recycling of concentrated sulfuric acid solution, basically eliminating the environmental problems caused by catalyst recovery. The added NH ₄ F and HF are also recycled, which greatly reduces the electrolysis voltage. , significantly improving the recovery effect of the catalyst.

The invention controls the metal recovery step by adjusting the concentration of sulfuric acid, and combines electrolysis and synergistic sulfuric acid for repeated use, so that the recovery rate of metal components in the catalyst is higher. The processing capacity of the system is much higher than that of the current catalyst recovery system, and basically no waste liquid is produced. In terms of atom utilization, other atoms are rarely introduced, which can not only eliminate the pollution caused by the recycling of the catalyst, but also achieve good economic benefits, and is conducive to the full recovery of the metal components of the catalyst.

The electrolysis operation of the present invention is a continuous reaction, the electrolyte flows continuously from beginning to end, the oxides dissolved by sulfuric acid are electrolyzed in the cathode chamber, the voltage is adjusted, and the electrolysis is performed in steps to realize flow operation and continuous reaction recovery. The catalyst of the invention has the advantages of high recycling rate, simple and efficient process, green environmental protection and high economic value. The catalyst can obtain high-purity molybdenum metal element, and can also separate high-purity metals such as nickel and cobalt.

Description of drawings

Fig. 1 is the framework diagram of catalyst recovery process steps of the present invention.

Fig. 2 is the electrolytic cell structure diagram of the present invention.

Fig. 3 is the catalyst recovery process flow chart of the present invention.

Detailed ways

The present invention is described in further detail below in conjunction with embodiment:

Example 1

(1) 1000g spent catalyst was first calcined at 550°C ((in terms of mass fraction (%), wherein MoO ₃ content was 15%, Co content was 10%, NiO content was 10%, Al ₂ O ₃ content was 60%, Fe ₂ O ₃ content is 5%), after cooling, pulverize the catalyst into 1200 mesh powder, divide it into 5 parts on average, first put 1 part of the powder into a fatty alcohol with a concentration of 3g/L (such as: C8-10 alcohol), carry out foam flotation, centrifuge the flotation catalyst for defoaming at a speed of 700 rpm, and carry out acid leaching on the defoamed catalyst, the acid leaching temperature is about 50 ° C, and the concentration of acid (sulfuric acid) is 3 mol /L, the acid leaching time is 2 hours, filter, and the filter residue is ready for use;

(2) the filtrate after filtration utilizes the concentration of alkali (caustic soda) to adjust the pH value of the alkali solution that is 5g/L, adjusts the pH=5 of aluminum, the pH=3 of iron, and reclaims aluminum and iron by step-by-step filtration;

(3) the filtrate after above-mentioned filtration to remove iron, aluminum is adjusted pH value, adjust pH to 3, carry out electrolysis after adjustment, electrolytic cell structure is as shown in accompanying drawing 2: adjust electrolytic voltage to be Ni=15V; Co=40V, simultaneously The concentration of the sulfuric acid solution obtained on the side of the semipermeable membrane (sulfate anion exchange resin) close to the cathode is 2 mol/L. This electrolysis step reclaims nickel and cobalt, and at the same time, a high-concentration sulfuric acid solution can be obtained for the next step.

(4) adding the remaining filter residue of step (1) in the vitriol oil after the above-mentioned recovery, the concentration of sulfuric acid is 7mol/L again, and the acid leaching temperature is 50 ° C, and the acid leaching time is 2 hours, and the acid leaching is filtered after the use of 3mol/L. The pH value of the filtrate was adjusted to 3 with L of NaOH solution, and NH ₄ F and HF were respectively added to make the concentration of the mixed solution reach 3 g/L, and electrolysis was carried out, as shown in Figure 2: Mo=50V, the semipermeable membrane was close to the cathode 1 The concentration of the sulfuric acid solution on the side is 4 mol/L, and then the recovery of the following 4 parts of catalyst is carried out.

Nickel, cobalt, iron, and molybdenum are recovered by metal quality/metal quality in spent catalyst=recovery rate, and the molybdenum content is determined by titration.

After the first recovery, the recovery rate of molybdenum was 97.9%, the recovery rate of nickel was 99.0%, the recovery rate of cobalt was 97.2%, the recovery rate of iron was 98.1%, and the recovery rate of aluminum was 98.3%.

After 5 total recoveries, the total recovery rate of molybdenum was 98.6%, the total recovery rate of nickel was 99.3%, the total recovery rate of cobalt was 98.5%, the total recovery rate of iron was 98.6%, and the recovery rate of aluminum was 99.3%.

The invention realizes the recycling use mode of the concentrated sulfuric acid solution, and the total recovery rate of the catalyst can be obviously improved after the multiple recycling operations of continuous reaction recovery.

Embodiment 2

Replace Ni=15V; Co=40V in Example 1 with Ni=10V; Co=30V. The scheme: the total recovery rate of molybdenum is 99.2%, the total recovery rate of nickel is 98.5%, the total recovery rate of cobalt is 97.9%, the total recovery rate of iron is 98.9%, and the recovery rate of aluminum is 99.0%.

Embodiment 3

The concentration of the NH _{4 F and HF solution added in Example 1 was 3 g/L, and the concentration of the added NH 4 F} and HF solution was 2 g/L instead. The scheme: the total recovery rate of molybdenum is 97.6%, the total recovery rate of nickel is 98.8%, the recovery rate of cobalt is 98%, the recovery rate of iron is 98.4%, and the recovery rate of aluminum is 99.4%.

Embodiment 4

Mo=50V in Example 1 is replaced by Mo=60V. The scheme: the total recovery rate of molybdenum is 94%, the total recovery rate of nickel is 98.6%, the total recovery rate of cobalt is 98%, the total recovery rate of iron is 98%, and the recovery rate of aluminum is 99.3%.

Comparative Example 1

The difference between Comparative Example 1 and Example 1 is that: no sulfate anion exchange resin membrane is provided in the electrolytic cell, and impurity-free sulfuric acid solution electrolyte is re-added during each electrolysis operation. Other conditions are the same as in Example 1,

After 5 times of total recovery, the total recovery rate of molybdenum was 88%, the total recovery rate of nickel was 87%, the total recovery rate of cobalt was 87%, and the total recovery rate of iron was 84%.

Without the sulfate anion exchange resin membrane, not only the sulfuric acid solution directly put into use cannot be recovered, but also the metal recovery rate is affected, which is not conducive to the full recovery of the metal components in the nickel-molybdenum catalyst.

Comparative Example 2

The difference between Comparative Example 2 and Example 1 is that NH ₄ F and HF are not added, and the voltage for recovering molybdenum metal at this time is 150V.

The overall recovery of molybdenum of Comparative Example 2 was 59%.

Without the addition of NH ₄ F and HF, not only the voltage for recovering molybdenum metal increases, but also the effect of recovering molybdenum at high voltage is unstable. Compared with Comparative Example 1, the recovery rate of molybdenum metal is significantly lower.

Claims (10)

1. a technique for wet recovery of iron, aluminum, nickel, molybdenum and cobalt from hydrorefining waste catalyst, is characterized in that: comprise the following steps: (1) calcining the waste nickel-molybdenum catalyst, pulverizing the catalyst into powder after cooling, using the foam flotation method for rough selection, and then defoaming; (2) put the catalyst after the rough selection into acid leaching in dilute sulfuric acid, filter, collect the filter residue for subsequent use, adjust the pH value of the filtrate to carry out step-by-step sedimentation, and recover iron and aluminum metal respectively; (3) adjust the pH value of the catalyst acid solution after reclaiming iron and aluminum metals, place in the electrolytic cell for electrolysis after adjustment, reclaim nickel and cobalt metals respectively, and collect sulfuric acid solution simultaneously; (4) adding the filter residue of step (2) into the concentrated sulfuric acid recovered in step (3) and adjusting the concentration acid leaching, filtering after the acid leaching, adjusting the pH value of the filtrate, adding NH ₄ F and HF solution, and electrolyzing in the electrolytic cell The molybdenum metal is recovered, and the sulfuric acid solution is obtained for recycling. 2. the technique of wet recovery of iron, aluminium, nickel, molybdenum and cobalt from the hydrorefining waste catalyst according to claim 1, is characterized in that: the foaming agent that the described froth flotation method of step (1) adopts is fat Alcohol; the particles crushed by the catalyst are between 180 and 1800 mesh, and the defoaming speed is 600 to 800 rpm. 3. the technology of wet recovery of iron, aluminum, nickel, molybdenum and cobalt from hydrorefining waste catalyst according to claim 1, is characterized in that: the temperature during step (2) acid leaching is 40～90 ℃, sulfuric acid The concentration is 2-4 mol/L, and the acid leaching time is 1-3 hours. 4. the technique of wet recovery of iron, aluminum, nickel, molybdenum and cobalt from the hydrorefining waste catalyst according to claim 1, is characterized in that: when step (2) regulates pH step-by-step precipitation, the pH= 1.5～3.5, pH=3.5～5.5 of recovered aluminum. 5. the process for wet recovery of iron, aluminum, nickel, molybdenum and cobalt from the hydrorefining waste catalyst according to claim 4, characterized in that: the pH=2～3 of the reclaimed iron, the pH=4～5 of the aluminum . 6. the technique of wet recovery of iron, aluminium, nickel, molybdenum and cobalt from hydrorefining waste catalyst according to claim 1, is characterized in that: electrolytic cell is made up of cathode, anode and anion exchange resin membrane; wherein to be recovered The metal is used as the cathode, the graphite is used as the anode, and the anion exchange resin is a sulfate anion exchange resin. 7. the technique of wet recovery of iron, aluminum, nickel, molybdenum and cobalt from the hydrorefining waste catalyst according to claim 1, is characterized in that: step (3) pH value is adjusted to 2～3, electrolytic recovery nickel metal The applied voltage is 2-20V, and the voltage is adjusted to 20-50V to recover cobalt metal. 8. the technology of wet recovery of iron, aluminum, nickel, molybdenum and cobalt from the hydrorefining waste catalyst according to claim 7, is characterized in that: the electrolytic recovery nickel voltage is 10～20V, and the recovery cobalt voltage is 30～40V . 9. the technique of wet recovery of iron, aluminum, nickel, molybdenum and cobalt from hydrorefining waste catalyst according to claim 1, is characterized in that: the concentration of step (4) sulfuric acid is 6～10mol/L, acid leaching The temperature is 40～60℃, and the acid leaching time is 1～3 hours. 10. the technology of wet recovery of iron, aluminum, nickel, molybdenum and cobalt from hydrorefining waste catalyst according to claim 1, is characterized in that: step (4) will utilize NaOH solution to adjust pH value to 2～4, The concentrations of NH ₄ F and HF in the filtrate were 1-5 g/L, respectively, and the voltage of Mo electrolysis was 30-60 V.

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