KR20080032057A - Method of recovering valuable metals from the vrds spent catalyst - Google Patents

Abstract

A method for recovering available metal from waste catalyst is provided to recover vanadium component and molybdenum component, which are contained in the waste catalyst, at a high yield. Oil and sulfur are removed from waste catalyst for petroleum desulfurization. The waste catalyst reacts with a caustic soda aqueous solution at a temperature of 135-160°C, thereby separating and forming aqueous reactants, such as sodium aluminate, sodium molybdate, and sodium vanadate, and non-aqueous reactants, such as nickel oxide, cobalt oxide, and impurities. The nickel oxide, the cobalt oxide, and the impurities are filtered off, and the sodium aluminate, the sodium molybdate, and the sodium vanadate are dissolved in a residual liquid.

Description

METHODS OF RECOVERING VALUABLE METALS FROM THE VRDS SPENT CATALYST}

The present invention relates to a method for recovering metals (hereinafter referred to as "soluble metals"), such as vanadium, molybdenum, nickel, and the like contained in spent petroleum desulfurization catalysts used to remove sulfur components present in crude oil.

A method of recovering and separating soluble metals such as vanadium and molybdenum contained in a conventional spent catalyst for desulfurization is as follows.

In order to remove oil from the recovered waste catalyst, the oil is recovered and recycled by applying a boiling point (BP) or higher to increase the temperature.The waste catalyst from which the oil is removed (heat is maintained at 400 ° C due to the removal of oil) is cooled before cooling. It guides the roasting furnace and maintains it at 400 ~ 600 ℃ and supplies oxygen (air) appropriately for the oxidation of sulfur and metal.

At this time, sulfur is oxidized, and molybdenum, vanadium, nickel, and cobalt are also oxidized to MoO ₃ , V ₂ O ₅ , NiO, and CoO. Sulfur is oxidized to sulfurous acid gas (SO ₂ ), which is led to an absorption tower (cap refinery) and absorbed in an aqueous solution of caustic soda (NaOH) flowing down from the top to form an aqueous solution of sodium sulfite (Na ₂ SO ₃ ). Discharged.

Here, in the case of nickel oxide and cobalt oxide, it is conventionally pulverized to recover, extracted with ammonia water, and then water has permeated, and has to be dried. Moreover, part of vanadium and molybdenum is converted into ammonia salt, which may cause confusion in separation. Since it is uneconomical to recover nickel from waste catalysts, the actual production site gives up the nickel recovery procedure and immediately proceeds to soda roasting.

As mentioned above, metal oxide and sodium carbonate are melted by mixing the oxidized waste catalyst with sodium carbonate (Na ₂ CO ₃ ) while maintaining the roasting temperature at 900 ° C while continuously and quantitatively and continuously injecting the nickel recovery into the rotary kiln. Aluminum is insoluble With a mixture such as sodium aldehyde, vanadium and molybdenum can be converted into soda salt to obtain water-soluble sodium vanadate (NaVO ₃ ) and sodium molybdate (Na ₂ MoO ₄ ).

Grind the roasted product obtained from soda melting and leaching with warm water at about 80 ℃ for 1 hour, filter it, collect the washed solution 1 ~ 2 times, adjust the pH to 8 and inject ammonium chloride (NH ₄ Cl) aqueous solution. Crystals of ammonium vanadate (NH ₄ VO ₃ ) begin to precipitate.

At this time, the amount of ammonium chloride is used more than the theory, and after the crystallization is finished, it is recovered by filtration and lowered to pH 2-3 to remove sulfate root (SO ₄ ^-2 ) in the mother liquor and then calcium chloride ( CaCl ₂ ) solution was added to remove the precipitate of calcium sulfate (CaSO ₄ ), and then the pH was raised to 7 again. Calcium chloride solution was injected. After complete precipitation of calcium molybdate (CaMoO ₄ ), it was filtered, washed with hydrochloric acid and oxidized. Made of Molybdenum

As described above, a rotary kiln facility is required as a facility for roasting at high temperature by mixing with soda carbonate, and a high temperature (900 ° C.) heat is required to maintain the melting point of soda. As it is not economical, nickel recovery should be given up, and waste catalyst has several species, but the amount of aluminum oxide used as excipient is about 65%, but it cannot be separated to make insoluble aluminum compound and treat it as waste. As the problem of waste of resources and insoluble aluminum compound treated as waste, 20% of noble metal vanadium and molybdenum are fused and leached, and the recovery rate of vanadium and molybdenum is less than 80%. The economic recovery is not a huge loss because of Groups are points that should be in stock on practicality.

In order to solve the above problems, the present invention can recover the vanadium and molybdenum components contained in the desulfurization waste catalyst at low temperature and high yield, and obtain nickel (NiO) and cobalt (CoO) without any additional steps. The present invention aims to provide a method for recovering soluble metals in a high-efficiency petroleum desulfurization (VRDS) waste catalyst which can recover the entire amount of aluminum (Al ₂ O ₃ ) used as an excipient.

In addition, it is an object of the present invention to provide a low-temperature metal recovery method of environmentally friendly petroleum desulfurization (VRDS) waste catalyst without the problem of environmental pollution or increased cost of purification due to a large amount of waste water containing ammonia nitrogen inevitably generated by the conventional method It is done.

The present invention for achieving the above object comprises a pretreatment step including a process of removing and oxidizing the oil and sulfur contained in the spent catalyst for petroleum desulfurization; The spent catalyst after the pretreatment step was put in an aqueous solution of caustic soda (NaOH) and reacted at 135 ~ 160 ° C. or higher, so that the water-soluble reactants such as sodium almine, sodium molybdate, sodium ammonium acid and water-insoluble non-reactant nickel oxide Separating and forming cobalt oxide and impurities; And filtering and removing the non-aqueous nickel oxide, cobalt oxide, and impurities, and the filtrate is left with sodium amine, sodium molybdate, and sodium vanadate in the mother liquor.

In another aspect, the present invention is the step of heating the filtrate of pH 15 including the sodium phosphate, sodium molybdate, sodium vanadate, heated to 80 ℃ or more, and then injecting hydrochloric acid or sulfuric acid while stirring to maintain the pH 9.5; Stopping the injection of acid when the pH is 9.5 in the above step and boiling over the reaction at 110 ° C. or higher to generate aluminum oxide, which is easy to filter; And recovering by filtering the aluminum oxide.

On the other hand, the present invention comprises the steps of treating the spent catalyst to obtain a solution containing sodium vanadate and sodium molybdate; Heating the solution to 80-90 ° C. while maintaining the pH at 1.0-1.0; And agitating the solution while stirring to precipitate molybdenum oxide and vanadium oxide.

In addition, the present invention comprises the steps of depositing ammonium vanadate by adding the mixture to the solution in which the molybdenum oxide and vanadium oxide precipitated in warm water at 80 ~ 90 ℃ and injecting ammonia water; And separating and recovering the precipitated ammonium vanadate crystals.

The present invention not only recovers the vanadium and molybdenum components contained in the desulfurization waste catalyst generated in the refinery in high yield, but also obtains nickel (NiO) and cobalt (CoO) without any special process and uses aluminum as an excipient. Al ₂ O ₃ ) provides an economical and high yield effect that can be recovered in its entirety.

In addition, since it does not use a high-temperature roaster, it is possible to use a reaction tube equipped with a pressureless double jacketed stirrer without the need for an expensive rotary kiln, which has the advantage of saving considerable equipment costs. Thermal efficiency is also high temperature of 900 ° C required for soda roasting. This is not necessary, but the minimum temperature required for low temperature agitation is required, which can also significantly reduce fuel costs in consideration of natural heating due to neutralization heat generation.

In addition, a large amount of wastewater including ammonia nitrogen, which is inevitably generated by the conventional method, is discharged, and there is an environmentally friendly advantage without causing a problem of environmental pollution or a problem of rising purification cost.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1.

The petroleum desulfurization waste catalyst can be pretreated by a known method. That is, the oil removal, sulfur removal, and metal oxidation of the spent catalyst are not particularly limited in the purification process of the material, and a known method may be used.

For example, by applying a temperature above the boiling point (BP) to remove the oil permeated to the spent catalyst, the oil can be recovered and recycled by steaming method or can be safely and accurately removed by solvent extraction.

The waste catalyst from which oil is removed is maintained at 400 ° C because of the heat remaining in oil removal, and it leads to the roasting furnace before cooling and maintains it at 400 ~ 600 ° C while adequately supplying the oxygen necessary for the oxidation of sulfur and metal.

At this time, along with the oxidation of sulfur, molybdenum, vanadium, nickel, cobalt (as MoO ₃ , V ₂ O ₅ , NiO, CoO, etc.) are also oxidized and sulfur is oxidized to sulfurous acid gas (SO ₂ ). ) Is absorbed by aqueous solution of caustic soda (NaOH) flowing down from the top, and is discharged downward as aqueous solution of sodium sulfite (Na ₂ SO ₃ ).

Next, the pretreated waste catalyst, such as oxidation treatment, is mixed with a caustic soda (NaOH) solution, stirred, and filtered to separate unreacted materials including nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ).

In one example, when 80 weight of water is injected into a reactor equipped with a stirrer and 80 weight of caustic soda (NaOH) is added to start stirring, caustic soda is dissolved by heat of dissolution. After heating at no pressure, it keeps 135 ~ 160 where steam is not discharged and inputs 100 weight of oxidized waste catalyst little by little, and keeps it at 135 ~ 160 ℃ when the input is finished. At this time, the exhaust valve is open for safety, but the steam does not come out very much, there can be no pressure. This is because when the solute is dissolved in the solvent, the boiling point increases and the freezing point decreases depending on the amount of the solute (Mol unit).

At this time, if the pressure is increased to 160 ℃ or more, it is more efficient when used, but there is a risk of explosion due to the burden of facility cost and pressure that the thickness of the container should be thickened when the pressure is applied.

When reacted at 160 ° C. for 2 to 3 hours, only NiO, FeO, CoO, etc. do not dissolve (the metal in which the metal oxide does not turn into an anion does not react with alkali), and 400 parts by weight of water is injected to crystallize the reactants. To prevent, dilute by stirring, stop the stirring and filter. The residue contains about 57% of nickel oxide (NiO), so that nickel can be easily separated.

Next, since aluminum (Al) is usually included in the desulfurization catalyst, aluminum is present in the filtrate, in which case it is required to separate it.

Sodium phosphate (NaAl (OH) 4) is present in the filtrate, and in order to remove it, first, by heating while rotating a stirrer, the temperature is raised to 85-90 ° C., followed by sulfuric acid or hydrochloric acid (HCl 20% -30%). Inject into the filtrate.

The temperature of the neutralization heat rises and the steam discharge valve should be opened for safety at the end of the reaction. At this time, hydrochloric acid may also be discharged, so it is necessary to properly adjust the amount of hydrochloric acid supplied. The end of the reaction is maintained at pH9.5, at which time aluminum oxide (Al ₂ O ₃ ) is produced, and the produced aluminum oxide (Al ₂ O ₃ ) is washed until vanadium is not detected in the wash water after filtration. Obtained by drying by sucking off the moisture permeated by the vacuum pump.

The method is equally applicable to tungsten. At this time, the sodium almate (NaAl (OH) ₄₎ is Al ₂ O _{3 And} sodium tungstate (Na ₂ WO ₄ ) is present in the aqueous solution.

The reaction between the filtrate and aqueous hydrochloric acid solution is preferably carried out in a temperature range of 95 ~ 120 ℃ in the range of pH 9 ~ 14.

In the reaction between the filtrate and aqueous hydrochloric acid solution, the conditions of 100 ℃ ~ 120 ℃ and pH 9.5 ~ 14 is very important.

The aluminum oxide reaction by temperature is shown in the following reaction formula.

Under the conditions of P.H9.5 ~ 14

① NaAl (OH) ₄ + HCl = Al (OH) ₃ + NaCl + H2O (0 ℃ ~ room temperature)

② NaAl (OH) ₄ + HCl = AlO (OH) + NaCl + 2H 2 O (80 ° C. to 95 ° C.): ① is mixed.

③ 2NaAl (OH) ₄ + 2HCl = Al ₂ O ₃ + 2NaCl + 5H ₂ O (100 ° C. to 120 ° C.): ② is mixed.

In the conventional method, since aluminum hydroxide (Al (OH) ₃ ) produced in the reaction of '①' is not filtered, a rotary kiln should be installed at a high cost. Although the purpose of making it insoluble was to separate soda vanadate and sodium molybdate, there was a problem that the insoluble aluminum compound, which is a waste, was disposed of in the state containing 20% of vanadium and molybdenum.

*

The product of the reaction '②' may be mixed in the '③' reaction, but it is filtered, so the above operation is fine. Therefore, preferably, when the reaction proceeds at 80 ° C or higher, the temperature rises to 110 ° C or higher by the heat of reaction. In particular, it is good to perform at a temperature of 100 ° C. or higher, which is almost free of aluminum hydroxide (Al (OH) ₃ ), and the upper limit temperature is not limited, but is limited to 110 ° C. to prevent unnecessary fuel consumption. It is necessary, and in particular to raise above the boiling point of the solution.

If you want to produce a single product (Al ₂ O ₃ ) of the '③' reaction is to pressurize in alkaline solution (pH9 ~ 14) to neutralize with hydrochloric acid while maintaining the temperature above 120 ℃ to remove the sodium (Na ₂ O). The mother liquor from which aluminum oxide was removed is dissolved in sodium vanadate (NaVo 3) and sodium molybdate (Na ₂ MoO ₄ ).

Hydrochloric acid is added dropwise to the filtrate so that pH is 2 or less, Mo is 1, and V is 1 or less. Preferably, the stirrer is rotated until the end of the reaction while the temperature is lowered to pH1 (pH-1) or lower and the temperature is maintained at 85 ° C.

Next, as shown in the following Chemical Formulas 1 and 2, the filtrate subjected to the above process was stirred at low temperature conditions within the range of 80 ~ 100 ℃, under acidic conditions of pH1 or less, and blown gas into the liquid continuously or discontinuously and aerated As a result, a mixture of vanadium oxide (V ₂ O ₅ ) and molybdenum oxide (MoO ₃ ) is precipitated and precipitated, thereby filtering.

When the air on the surface of the reaction tube is sucked and the aspirated air is blown back into the liquid to aeration, bubbles are ruptured and dehydration reactions as shown in the above reaction occur, causing metal oxides to precipitate. In the case of molybdenum, dehydration reaction occurs even when heated to pH1 ~ 2, however, there is a problem that the speed is slow and the temperature must be quite high, but the aeration can cause the dehydration reaction even at low temperatures. It can be a breakthrough. Vanadium oxide (V ₂ O ₅ ) and molybdenum oxide (MoO ₃ ) precipitate as an amorphous crystal and are obtained by filtration washing with water.

An acid aqueous solution may be used for the acidic condition, and an acid may be added to be an acidic condition of pH 2 or less, more preferably pH 1 or less, and the reaction conditions may be performed at 80 ° C. or higher. The temperature is significantly lower than the conventional method, there is an advantage that does not require a particularly high temperature.

In order to cause such an aeration phenomenon, there is also a method of sucking the air in the reactor and blowing into the liquid, or may suck the atmosphere and blow into the liquid. At this time, the temperature and humidity of the atmosphere may be different from the conditions in the reaction tube, it is good to provide a separate device to match this.

This makes it possible to recover noble metals vanadium and molybdenum.

In addition, ammonium vanadate (NH ₄ VO ₃ ) and ammonium molybdate (NH ₄ ) ₂ formed by adding ammonia water to the mixture of vanadium oxide (V ₂ O ₅ ) and molybdenum oxide (MoO ₃ ) precipitated above and stirring By filtering the precipitated crystals of ammonium vanadate (NH ₄ VO ₃ ) using the solubility difference of MoO ₄ ), ammonium vanadate (NH ₄ VO ₃ ) and ammonium molybdate ((NH ₄ ) ₂ MoO ₄ ) May be further performed.

Since the obtained vanadium oxide and molybdenum oxide are co-precipitated, they are separated and washed from the mother liquor, and then poured into water at 80 to 90 ° C. and neutralized with ammonia water (NH ₄ OH) while stirring. The reaction results in the formation of ammonium vanadate (NH ₄ VO ₃ ) and ammonium molybdate ((NH ₄ ) ₂ MoO ₄ ), solubility of ammonium vanadate (NH ₄ VO ₃ ) is relatively low. These can be separated using a separation method such as recrystallization.

When the crystals are precipitated, they are filtered, washed with water, and dried. When the ammonium molybdate is low in the mother liquor, V ₂ O ₅ and MoO ₃ are added, NH ₄ OH is injected, heated again, dissolved, cooled, and vanadine repeatedly. Ammonium vanadate (NH ₄ VO ₃ ) and molybdenum were obtained by minimizing the dissolved amount of NH ₄ VO _{3 in} the mother liquor by obtaining ammonium acid (NH ₄ VO ₃ ) and repeating it until the specific gravity of the mother liquor was about 2.5. Ammonium acid ((NH ₄ ) ₂ MoO ₄ ) is obtained.

The mother liquor after the above process is a high solubility of ammonium molybdate and may have a high specific gravity or a low specific gravity. The cause may be due to the small and large amount of water as a solvent, and may be due to the amount of molybdenum in the spent catalyst (raw material), but when the specific gravity is 2.5 or less, the above reaction (reaction of coprecipitation and ammonia) may occur. If the specific gravity becomes more than 2.5 by reuse and remove ammonium vanadate after 12 hours, the mother liquor is ammonium molybdate (NH ₄ ) ₂ MoO ₄ and the vanadium is 0.0x% or less. have.

Further additionally, at least one or more of the ammonium vanadate (NH ₄ VO ₃ ) and the ammonium molybdate ((NH ₄ ) ₂ MoO ₄ ) obtained above may be thermally decomposed again to vanadium oxide (V ₂ O ₅ ) or / and molybdenum oxide. (MoO ₃ ), and the ammonia gas generated at this time is dissolved in water and reused as the ammonia water described above.

As mentioned above, there are about 10 kinds of spent catalysts, and the ratios of the contents are different and the components are changed. However, all of the waste catalysts are included in the present invention because the recovery method of the present invention can be applied within the scope of the claims of the present invention.

1 is a flowchart of a method according to an embodiment of the present invention.

Claims (4)

In the method for recovering the soluble metal from the spent catalyst for petroleum desulfurization, A pretreatment step including removing oil and sulfur contained in the spent catalyst for petroleum desulfurization; The spent catalyst after the pretreatment step was put in an aqueous solution of caustic soda (NaOH) and reacted at 135 ~ 160 ° C. or higher, so that the water-soluble reactants such as sodium almine, sodium molybdate, sodium vanadate and non-aqueous non-reactant nickel oxide Separating and forming cobalt oxide and impurities; And The non-aqueous nickel oxide, cobalt oxide and impurities are filtered and removed, and the filtrate is dissolved in sodium phosphate, sodium molybdate and sodium vanadate. The soluble metal in the spent catalyst for petroleum desulfurization, comprising: How to recover. The method of claim 1, Maintaining the reaction at pH 9.5 by heating the filtrate including sodium phosphate, sodium molybdate, and sodium vanadate to be heated to 80 ° C. or higher and then injecting hydrochloric acid or sulfuric acid with stirring; Stopping the injection of acid when the pH is 9.5 in the above step and boiling over the reaction at 110 ° C. or higher to generate aluminum oxide, which is easy to filter; And And recovering the soluble metal from the spent catalyst for petroleum desulfurization further comprising filtering and recovering the aluminum oxide. In the method for recovering the soluble metal from the spent catalyst for petroleum desulfurization (VRDS), Treating the waste catalyst to obtain a solution containing sodium vanadate and sodium molybdate; Heating the solution to 80-100 ° C. while maintaining the pH at 1.0-1.0; And Aerated while stirring the solution to precipitate the molybdenum oxide and vanadium oxide; Method for recovering the soluble metal from the spent catalyst for petroleum desulfurization. The method of claim 3, Into the solution of molybdenum oxide and vanadium oxide, the mixture was poured into hot water at 80 to 90 ° C., and mixed with ammonia water to stir to precipitate ammonium vanadate having low solubility and ammonium molybdate having relatively high solubility in the mother liquid. Dissolving to dissolve; And Separating and recovering the precipitated ammonium vanadate crystals; Method for recovering the soluble metal in the spent catalyst for petroleum desulfurization.

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