KR20160127978A

KR20160127978A - Process of preparing molybdenum trioxide from molybdenite

Info

Publication number: KR20160127978A
Application number: KR1020150059601A
Authority: KR
Inventors: 김지혜; 이성환; 임채선; 이정석
Original assignee: (주)포스코엠텍
Priority date: 2015-04-28
Filing date: 2015-04-28
Publication date: 2016-11-07
Also published as: KR101878913B1

Abstract

The present invention relates to a process for preparing a trioxide of molybdenum from a molybdenum concentrate regardless of the content (refined) of molybdenum, it is first oxidized to molybdenum concentrate at the same time as the desulfurization by using nitric acid, aqueous ammonia (NH ₄ OH) molybdenum by a solution of acid Is selectively evaporated to a low-temperature and low-pressure state, recovered as solid ammonium molybdate ((NH ₄ ) ₂ MoO ₄ ), and then dried and pyrolyzed to prepare molybdenum trioxide (MoO ₃ ). In addition, nitrogen oxide (NOx gas) and ammonia (NH ₃ gas) generated during the process are regenerated and reused in the process, molybdenum is recovered from the generated waste liquid, sulfuric acid generated during the reaction is removed, It is characterized by. Accordingly, the present invention can produce molybdenum trioxide at a high yield from molybdenum concentrate.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for preparing molybdenum trioxide from molybdenum concentrate,

The present invention relates to a process for producing molybdenum trioxide from molybdenum concentrate and more particularly to a process for producing molybdenum oxide from a molybdenum sulfide concentrate using a wet smelting process at atmospheric pressure and recovering molybdenum from the process water generated during the process .

A method of producing molybdenum oxide (MoO ₃ ) from molybdenite molybdenum concentrate (MoS ₂ ) has been used as desulfurization using roasting, which is a dry smelting method, and leaching using an acid such as a wet smelting method.

Molybdenum oxide (molybdenum oxide or molybdenum trioxide, hereinafter referred to as "molybdenum oxide") is produced when molten metal is molten in molybdenum concentrate (hereinafter, molybdenum sulfide and molybdenum sulfide are referred to as molybdenum concentrate) , The initial element content has a large effect on the molybdenum oxide to be produced since the dry process does not have a separate process for removing the impurities contained in the molybdenum oxide. In the case of molybdenum concentrates generated as copper (Cu) mines or other by-products, the content of certain elements other than molybdenum is high, resulting in a decline in the quality of the produced molybdenum oxide, resulting in a decline in the quality value. Therefore, in the case of using a dry smelting process, a purification process using wet smelting after a dry roasting is a necessary step in order to obtain a product of high purity.

On the other hand, when using the wet smelting process, it is possible to produce molybdenum oxide of high quality and recover a small amount of valuable metal contained in the by-product. Methods for producing molybdenum oxide from a molybdenum concentrate using a wet smelting method include an acid, an alkali leaching method, a high pressure leaching method, an oxidizing agent application method, and an electrooxidation method. Recently, as the demand for a high purity raw material metal increases, There is growing interest in wet smelting methods that can be applied.

The wet smelting of molybdenum concentrates is roughly classified into an acid treatment method and an alkali treatment method. The acid treatment method is a method of producing molybdenum concentrate as a final molybdenum oxide by adding an acid at atmospheric pressure or high pressure to desulfurization (hereinafter, "desulfurization" is referred to as "conversion reaction"). Generally, sulfuric acid, hydrochloric acid (HCl) And molybdenum oxide is produced by leaching at a high temperature and a high pressure of 5 to 10 atm and a temperature of 150 to 250 ° C in a special pressure vessel called Autoclave. In this case, expensive investment cost is required, and there is a drawback that air pollution is caused by the emission of NOx, SOx and Cl ₂ generated during the conversion reaction.

The alkali treatment method is a method for recovering molybdenum oxide by synthesizing and evaporating the leach solution after mixing water with alkaline caustic soda (NaOH) / potassium hydroxide (KOH) / ammonia water (NH ₄ OH) Has a disadvantage in that it has a large influence on the quality due to excessive Na content in the molybdenum oxide produced and it is difficult to treat the wastewater generated after treatment using strong acid when synthesized.

Korean Patent No. 10-0700348

It is an object of the present invention to provide a method for recovering high-purity molybdenum oxide from a molybdenum concentrate at a high yield.

According to an aspect of the present invention, there is provided a process for producing molybdenum concentrate, comprising: a conversion step of converting a molybdenum concentrate raw material into an oxide simultaneously with desulfurization with nitric acid; A nitric acid regeneration step of regenerating NOx gas generated in the conversion step as nitric acid; A cooling washing step of cooling and washing the acid component of the molybdate (Molybdate, H ₂ MoO ₄ , MoO ₃ ? XH ₂ O) oxide converted in the conversion step; A gypsum producing step of removing gypsum from the conversion filtrate resulting from the conversion step and forming gypsum; A nitrate regeneration step of adjusting the concentration of the solution generated in the nitrate regeneration step and the gypsum production step to a conversion step; Dissolution step of dissolving the molybdenum oxide is converted cake washing in the washing step by cooling the ammonia water (NH ₄ OH) solution in the dissolution tank; Removing undissolved residues remaining as residues in the dissolution step by washing with water, filtering the remaining undissolved residues from the dissolution reaction tank, and separating the undissolved residues; (NH ₄ ) ₂ MoO ₄ ) is precipitated by evaporating the dissolved filtrate from which the unreacted residue has been separated under reduced pressure in a concentrated evaporator, and then recovered by filtration with a centrifugal separator; A dry pyrolysis step of recovering molybdenum trioxide through moisture drying of the solid ammonium molybdate generated in the concentration and evaporation step and pyrolysis of ammonia; An ammonia regeneration step of regenerating ammonia gas generated in the concentrating and drying pyrolysis step; And recovering valuable metals such as molybdenum and copper by precipitating from the process water generated in the cooling washing step, the gypsum production step and the un-dissolved residue separation step to a hydroxide state by controlling the pH, and a valuable metal recovery step Wherein the molybdenum concentrate is a molybdenum concentrate.

According to one embodiment, the molybdenum concentrate feedstock is a molybdenum concentrate having an oil content of less than 2 vol.%, Or a slurry of molybdenum concentrate having an oil content of 2 to 7 vol.%. If the oil content of the raw material used in the raw material slurry forming step (S100) is less than 2%, the raw material is directly introduced into the conversion step (S200). If the oil content is less than 2 to 7% .

According to another embodiment, the slurry is prepared by using water, or by using the gypsum filtrate produced in the gypsum production step, or by using the solution obtained in the nitrate-adjusting step. A process for producing molybdenum is disclosed. As the gypsum filtrate, it is preferable to use a gypsum filtrate having a sulfuric acid concentration of less than 3% and a nitric acid concentration of less than 3%, and the slurry is preferably mixed in a temperature range of 5 to 30 캜.

According to another embodiment, the nitric acid solution used in the conversion step is a nitric acid solution having a concentration of 10 to 30% by volume, and the conversion step is carried out in a temperature range of 60 to 100 ° C and 0.5 to 1.2 bar Wherein the molybdenum concentrate raw material is fed at a reaction pressure of 9.3 to 12 L / min. The molybdenum concentrate raw material feed rate is 9.3 to 12 L / min. The concentration of the nitric acid solution can be changed according to the molybdenum content of the molybdenum concentrate used.

According to another embodiment, the nitrate regeneration step oxidizes the NOx in an oxidizer maintained at 100-400 占 폚, then recycles it into nitric acid by passing it through an aeration tank and a poling absorber, And the NOx gas is passed through a NOx scrubber to be completely removed and discharged to the atmosphere. The regenerated nitric acid can be reused in the process.

According to yet another embodiment, the ammonia solution used in the dissolution stage (NH ₄ OH) solution was maintained at a temperature 5 to 40 ℃ and pH 7.5 to 8.5, the dissolution is trioxide, characterized in that is carried out for 0.5 to 2 hours. A process for producing molybdenum is disclosed.

According to another embodiment, in the concentrated evaporation step, the unmelted residue is removed in the dissolution step and the remaining dissolution liquid is reduced to 400 to 500 mmHg in a concentrated evaporation tank at 60 to 80 DEG C The molybdenum trioxide is reacted for 10 to 20 hours while maintaining the temperature of the molybdenum trioxide.

According to another embodiment, the concentrating and evaporating step is carried out without stirring, and is carried out with stirring from the beginning of the stirring.

According to another embodiment, the starting point of the agitation is in the range of 25% to 75% of the initial reaction time.

According to another embodiment, in the dry pyrolysis step, the drying is performed by maintaining the solid ammonium molybdate generated in the concentration and evaporation step at a temperature of 80 to 100 ° C. for about 1 to 3 hours. do. It is preferable that the drying is performed so that the moisture content in the solid ammonium molybdate is 0.5 to 5 wt% or less.

According to another embodiment, pyrolysis in the dry pyrolysis step is carried out by transferring the dried ammonium molybdate to a fluidized-bed reactor, and thereafter introducing air at 350 to 600 ° C at a flow rate of 2 to 16 m / s and at a rate of 400 to 2000 L / By introducing an ammonium molybdate fluidized bed into the fluidized-bed reactor at a flow rate of at least < RTI ID = 0.0 > 100% < / RTI >

According to another embodiment, the concentration of sulfuric acid in the conversion filtrate resulting from the conversion step used in the gypsum production step is 6 to 21% by volume, and the slurry slurry in the gypsum production step is 50 To 1,000 kg, and the step of preparing gypsum is carried out by reacting at a temperature of 20 to 50 DEG C for 1 to 4 hours to prepare a molybdenum trioxide.

According to yet another embodiment, the calcium hydroxide slurry is then initiated room molybdenum trioxide produced, characterized in that the prepared mixture of water of 50 to 900 kg of calcium oxide and from 0.2 to ³ m 3.

According to another embodiment, the method further comprises the step of mixing the acidic solution generated in the cooling cleaning step or the acidic solution generated in the step of producing the gypsum, or a mixture thereof and the basic solution generated in the un- A molybdenum trioxide production chamber is disclosed.

According to another embodiment, the mixing is carried out by maintaining the stirring at room temperature for 1 to 3 hours such that the pH is between 3.5 and 4.5. A molybdenum trihydrate production chamber is disclosed. In the process of the present invention, a small amount of molybdenum remains in the wastewater generated, and the recovery rate of the entire process can be increased by recovering the molybdenum. Particularly, the acidic wastewater generated in the cooling washing step or the gypsum production step and the alkaline wastewater generated in the separation step are introduced into the reaction tank at a ratio of about 1: 2, for example, and stirred at room temperature for 1 to 3 hours So that the molybdenum in the wastewater can be recovered by precipitating in a molybdenum oxide state.

According to another embodiment, the step of measuring the amount of NOx gas generated in the conversion step, or the step of analyzing the concentration of nitric acid generated in the conversion step, or all of these steps is further included. Molybdenum production room is started.

According to another embodiment, an ammonia regeneration step of regenerating ammonia generated in the concentrating and evaporating step, or ammonia generated in the drying pyrolysis step, or ammonia generated in the concentrating and evaporating step and the drying pyrolysis step, with ammonia water is added A molybdenum trioxide production chamber is disclosed. Thus, it can be regenerated with ammonia water and used in the dissolution step together with, for example, 25 vol.% Ammonia water.

In the present invention, first, molybdenum concentrate is converted by using nitric acid, molybdenum is selectively dissolved by ammonia water (NH ₄ OH) solution, and the metal elements added to the remaining concentrate are not dissolved so that the separation of these metal elements and molybdenum component It is possible to effectively recover molybdenum having high purity.

In addition, the present invention regenerates the ammonia gas generated during the pyrolysis process, the nitrogen gas generated from the desulfurization step, and the ammonia gas generated during the evaporation / condensation / pyrolysis process and recycles them as nitric acid and ammonia, It is possible to produce additional gypsum byproducts by producing gypsum, which is a by-product of sulfuric acid generated in the process water. The filtrate generated after the gypsum production can be reused and the water can be saved.

In addition, the present invention can increase the recovery rate by recovering molybdenum from the process water and the waste liquid by the precipitation method.

1 is a flow chart showing a method for producing molybdenum oxide from a molybdenum concentrate according to the present invention.
FIG. 2 is a detailed explanatory diagram of the conversion step (S200), the nitrate regeneration step (S210), and the nitric acid adjustment step (S220) in the present invention.
FIG. 3 is a detailed explanatory view of the cooling cleaning step (S300) of FIG. 1 in the present invention.
4 is a detailed explanatory view of the gypsum manufacturing step (S310) of FIG. 1 in the present invention.
FIG. 5 is an explanatory diagram illustrating in detail the dissolution step (S400) and the concentration and evaporation step (S600) of FIG. 1 in the present invention.
FIG. 6 is a detailed explanatory diagram of the dry pyrolysis step (S700) and the ammonia regeneration step (S510) of FIG. 1 in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a method for effectively producing high-purity molybdenum oxide from molybdenum concentrate, comprising the steps of (A) slurrying a raw material slurry (S100), (B) converting S200, (C) (E) cooling washing step (S300), (F) gypsum manufacturing step (S310), (G) dissolving step (S400), (H) un-dissolved residue separation (S210), (D) nitric acid adjusting step (S220) (K) ammonia regeneration step (S610), (L) recovering the valuable metal (S800), and the like. The step (S600) Each of these steps will be described below.

(A) Slurrying the raw material (S100)

In this step, the molybdenum concentrate (hereinafter, molybdenum concentrate is referred to as a "raw material ") as a raw material is supplied to the slurry tank 10 for the subsequent step of the molybdenum concentrate, . In this case, depending on the amount of oil contained in the raw material, the clogging phenomenon and handling of the pump may be inconvenient at the time of transfer to a later stage. Therefore, if the oil content is less than 2%, the raw material It may be charged directly. If it is 2 to 7%, it is converted into a slurry. At this time, the reaction tank at the time of mixing the raw material with the water or gypsum filtrate (sulfuric acid concentration 3%, nitric acid concentration 3% or less) is maintained in the temperature range of 5 to 30 ° C. If the amount is less than the lower limit, there is a problem that the rate of the mixing reaction is delayed. If the upper limit is exceeded, there is a problem that the cost of heating the reaction tank becomes excessive. The mixing ratio is preferably about 1: 5 by weight, and it is more preferable that the raw materials to be used are all irrespective of the grade and slurried while agitating to further increase the slurrying efficiency (refer to FIG. 2).

(B) Conversion step (S200)

In this step, the raw slurry (31) or raw material prepared by the raw slurry forming step (S100) is put into a conversion reaction tank (11) containing a water or gypsum filtrate (41) The sulfur (S) contained in the raw material is removed, and at the same time, the raw material is oxidized. The reaction of the raw material with nitric acid to form NOx is represented by the following reaction formula (1).

[Reaction Scheme 1]

MoO ₂ (s) + 6HNO ₃ (l) + impurity (s) = MoO ₃ H ₂ O (s) + 6NO (g) + 2H ₂ SO ₄

At this time, the conversion reaction tank 11 used for the conversion is maintained in the temperature range of 60 to 100 캜. If the amount is less than the lower limit value, there is a problem that the conversion reaction rate is slow. If the upper limit value is exceeded, there is a problem that the cost for heating the reaction tank becomes excessive. The reaction time is preferably 15 to 24 hours. If the reaction time is less than 15 hours, the conversion reaction may not occur properly. If the reaction time exceeds 24 hours, unnecessary expense loss and excessive mechanical equipment may occur. The nitric acid concentration is preferably 10 to 30% by volume. If the concentration of nitric acid is less than the lower limit of the above range, desulfurization by acid may not occur properly, and if the concentration exceeds the upper limit, air pollution due to excessive NOx may occur. The feed rate of the raw material slurry is 9.3 to 12 L / min, the reaction tank pressure is 1.2 bar or less, and it is more preferable to switch while stirring to further increase the reaction efficiency (refer to FIG. 2)

(C) Nitric acid regeneration step (S210)

In order to regenerate the NOx gas generated during the reaction of the conversion step S100, when 1 mole of MoS ₂ is converted into MoO ₃ H ₂ O (or H ₂ MoO ₄ ) as in the reaction formula 1, Is generated. And regenerating the generated NOx gas with nitric acid. The NOx gas is generated as described above is moved to the first oxidizer 15, in contact with the cold oxygen 32 flowing to the oxidizer 15, a portion of NOx gas reacts with O ₂ is oxidized to NO ₂ , Some oxidized NO ₂ may be converted to N ₂ O ₄ . At this time, the oxidizer temperature is maintained at 100 to 400 ° C. If the temperature is lower than the lower limit value, there is a problem that the oxidation rate is slow. If the upper limit value is exceeded, there is a problem that the cost for heating the oxidizer is excessive. This reaction is represented by the following Reaction Schemes 2 and 3.

[Reaction Scheme 2]

NO (g) + 1 / 2O ₂ (g)? NO ₂ (g)

[Reaction Scheme 3]

_{2NO 2 (g) → N 2} O 4 (g)

This would through an oxidation of the 3-converted to such NO ₂ or N ₂ O _4, moves to the Second Process of the aeration tank 12, the aeration tank inside plaster filtrate 41 is generated in the gypsum production phase (S310) or water ( 33) is always contained in 1/4 to 1/5 of the reaction tank. At this time, the NOx gas meets the water (33) as it is sprayed through a special nozzle made in the aeration tank, This occurs irregularly and is nitrified.

[Reaction Scheme 4]

N ₂ O ₄ (1) + H ₂ O (1) → HNO ₃ (1) + HNO ₂ (1)

[Reaction Scheme 5]

_{2NO 2 (g) + (H} 2 O) n → NO 3 - NO + --- (H 2 O) n

[Reaction Scheme 6]

NO ₃ ^- NO ⁺ --- (H ₂ O) _n → NO ₃ ^- + NO ⁺ + H ⁺ + HO + (H ₂ O) _{n -1}

[Reaction Scheme 7]

_{HNO 3 (l) + HNO 2} (l) → 2HNO 2 (g) + O 2 (g)

[Reaction Scheme 8]

2HNO ₂ (g) + O ₂ (g)? 2HNO ₃ (1)

The NOx gases that have not been nitrified by the two stages through the aeration tank 12 are again transported to the absorption tower 13 and the inside of the absorption tower 13 is divided into seven stages. The poling 34 is divided into 6 stages Is more effective for NOx absorption reaction. Then, the NOx gas that has not been sucked is adjusted to a reference concentration or lower in the NOx scrubber 14 to discharge the gas into the atmosphere (see FIG. 2).

(D) nitric acid adjustment step (S220)

The concentration of nitric acid produced by the absorption of the NOx gas in the aeration tank 12 and the absorption tower 13 of the nitrate regeneration step S210 is very high at 30 to 80% by volume. Therefore, in this step, the concentration of nitric acid is appropriately adjusted and diluted so as to be used in the conversion reaction tank 11. The high concentration nitric acid generated in the aeration tank 12 and the absorption tower 13 and the gypsum filtrate 41 generated in the gypsum production step S310 are mixed in the nitric acid adjustment tank 16 and adjusted to an appropriate concentration, ) (See Fig. 2).

(E) Cooling cleaning step (S300)

When a certain period of time (reaction time) elapses in the conversion step S200, the product remains in a mixed form of sulfuric acid, molybdenum oxide, and impurities as shown in Scheme 1. Since the temperature during the reaction is 60 to 100 ° C, The air is introduced for 1 to 4 hours to aeration to cool the product to a temperature of 40 DEG C or less and at the same time the NOx gas remaining in the reaction vessel is oxidized in the oxidizer 15, Lt; / RTI > Thereafter, the filtrate 40 is transferred to the gypsum bath 18, and the conversion cake as a residue is sent to the washing tank 19 for washing. At this time, water 36 is introduced into the washing tub 19 in advance. Washing is carried out for 0.5 to 2 hours. If the washing time is less than 0.5 hour, it is difficult to remove all impurities and remaining chemical components remaining in the conversion cake. If the washing time is more than 2 hours, unnecessary loss of the cost and washing efficiency may be reduced. At this time, the ratio of the water (36) to the conversion cake is 1: 5 to 1:10. At this time, stirring is necessary to increase the cleaning efficiency. After completion of the washing, solid-liquid separation is carried out using the washing-exclusive filter press machine 21, and then the solid conversion cake is transferred to the dissolution tank 23 of the dissolution step (S400), and the filtrate is transferred to the washing water storage tank (See FIG. 3).

(F) Gypsum production step (S310)

The conversion filtrate 40 generated in the cooling and washing step S300 is collected in the gypsum tank 18. When 1 mole of the raw material (MoS ₂ ) is reacted as in Scheme 1, 2 moles of sulfuric acid is produced. This sulfuric acid is unnecessary during the process and removes sulfuric acid since it may be difficult to control the conversion step (S200) due to unstable reaction due to excessive sulfuric acid even though it is reused as process water.

In order to solve the above problem, the quicklime 43 of the quicklime supply tank 60 is dropped into the water of the slaked lime reacting tank 61. At this time, when the quicklime is reacted with water as in the reaction formula (9), slurry (44) in which calcium hydroxide (Ca (OH) ₂ ) is mixed with water is made. At this time, the ratio of water to calcium oxide 43 is 4: 1. The amount of slurry is 500 to 1000 kg according to the concentration of sulfuric acid, and the reaction is carried out at 50 ° C or lower for 1 to 4 hours. Particularly when the sulfuric acid concentration is 6 to 21%

Quicklime and water of 0.2 to 3 m ³ of 50 to 900 kg are mixed. Stirring the slurry for reactivity and raising the temperature of the slaked slurry 44 due to the exothermic reaction in the process of producing the slaked slurry 44 as shown in the following reaction equation (9), so that the slaked slurry 44 are controlled so as not to exceed 40 占 폚. When the reaction time is about 0.5 to 1 hour per 1 ton, sufficient reaction is achieved.

[Reaction Scheme 9]

CaO (S) + 2H ₂ O (1)? Ca (OH) ₂ + H ₂ O (1)

The slaked slurry (44) is dropped into the conversion filtrate (40) of the gypsum reaction tank (18). At this time, the input amount of the slaked lime slurry (44) should be such that the sulfuric acid concentration in the conversion filtrate (40) is confirmed, and only about 3% of the sulfuric acid is allowed to remain in the solution. The slaked lime slurry can remove the sulfuric acid remaining in the conversion filtrate 40 and produce gypsum.

[Reaction Scheme 10]

Ca (OH) ₂ (S) + H ₂ SO ₄ (1)? CaSO ₄ ? 2H ₂ O (S)

The gypsum produced as described above is solid-liquid separated by using a gypsum-dedicated filter press 45, and solid gypsum can be obtained as gypsum by-product after passing through a gypsum dryer 46 in order to lower the moisture content of the gypsum after washing. At this time, the generated gypsum filtrate 41 is sent to the raw slurry step S100 or the nitrate adjustment step S220, and can be suitably used (refer to FIG. 4).

(G) dissolution step (S400)

The conversion cake generated in the cooling and washing step is dropped into the dissolution reaction tank 23. At this time, water (37) of about 2.5 to 5 times the conversion conversion cake is supplied to the dissolution reaction tank (23) Fill in beforehand. Then, the ammonia water 42 in the ammonia water storage tank 39 or the regenerated 25 vol% ammonia water is introduced. At this time, when stopping the introduction of ammonia water, it is preferable that the pH is kept at 8 to 8.5, and the stirring is continued for 0.5 to 2 hours after the pH is kept constant while stirring, and the temperature is maintained in the range of 5 to 40 ° C.

As described above, in the present invention, when ammonia water (NH ₄ OH) is used to dissolve the molybdenum oxide as the conversion cake, molybdenum oxide is dissolved by ammonia water, while silica (Si), which is a main component of the molybdenum concentrate, (NH ₄ ) ₂ MoO ₄ ) is synthesized by simple filtration using silica, magnesium (Mg), alumina (Al ₂ O ₃ ), and the like. ) (See FIG. 5).

[Reaction Scheme 11]

H ₂ MoO ₄ (L) + 2 NH ₄ OH (L) + unheated residue (S) → (NH ₄ ) ₂ MoO ₄ (L)

(H) Un-dissolved residue separation step (S500)

When the dissolution reaction in the dissolution reaction tank 23 is completed by the dissolution step S400, the undissolved residues are separated by filtering the undissolved residues with a filter press 24 dedicated to the dissolution reaction tank to separate the molten residue from the filtrate The process proceeds to the following concentration and evaporation step (S600).

(I) concentration and evaporation step (S600)

When the undissolved residue is removed by the unisonized residue separation step (S500) and the remaining filtrate is transferred to the concentrated evaporation tank (25), a reduced pressure of about 450 mmHg is applied to the concentrated evaporation tank (25) The temperature is raised to a temperature of 60 to 80 DEG C and the solution is concentrated to about 1/5 of the initially introduced dissolved filtrate. During the concentration process, ammonium molybdate ((NH ₄ ) ₂ MoO ₄ ) is precipitated, and the precipitated ammonium molybdate is collected by filtration with a centrifuge 26. At this time, the filtrate generated during the filtration remains in the concentrating evaporator (25), which is used when the concentrate is evaporated by mixing in the next order in the continuous production progress.

(J) Dry pyrolysis step (S700)

Solid generated in the concentrated evaporation step (S600) is to a degree of moisture of 10 to 30% of ammonium molybdate _{(NH 4) 2 MoO 4)} , passed through a dryer 27, in Step 1, drying the water, wherein the drier ( 27) is maintained at a temperature of 80 to 100 ° C, and moisture in the ammonium molybdate is dried to 5% or less, and the residence time is suitably 1 to 3 hours. Ammonium molybdate having partially dried water is introduced into the hopper of the fluidized-bed reactor 28. At this time, the air in the air storage 20 is reduced at a flow rate of 2 to 16 m / s at a flow rate of 400 to 2000 L / Molybdenum trioxide can be produced by pyrolysis of ammonium molybdate as shown in Reaction Scheme 12 by warming the fluidized-bed reactor 28 by preheating it at 350 to 600 ° C by blowing it into the furnace.

[Reaction Scheme 12]

(NH ₄ ) ₂ MoO ₄ → MoO ₃ + 2NH ₃ + H ₂ O

(K) ammonia regeneration step (S610)

The gas generated in the dry pyrolysis step (S700) and the evaporation concentration step (S600) is generated by the decomposition of ammonia as ammonia gas. Since the generated ammonia gas is at a high temperature, it is cooled down through the heat exchanger 50 and flows into the ammonia regenerator 29. At this time, the water 48 is filled in the ammonia regenerator 29, so that the ammonia water is mixed with the introduced ammonia to produce ammonia water. At this time, if the temperature in the ammonia regeneration device 29 is maintained at 0 to 15 ° C or lower, ammonia of 90% or more can be regenerated. The remaining ammonia gas is then removed from the ammonia scrubber 30 filled with sulfuric acid 49. This reaction is represented by the following reaction formula (12).

[Reaction Scheme 12]

2 NH ₃ + H ₂ SO ₄ → (NH ₄ ) ₂ SO ₄

(L) Valuating metal recovery step (S800)

In some of the above inventions, wastewater was generated, and a small amount of molybdenum remained in the wastewater. Such molybdenum is recovered and used as a method for increasing the recovery rate of the whole process. Especially, there are two characteristics of wastewater generated. And the alkali wastewater generated in the acidic wastewater separation step (S500) and the acidic wastewater separation step (S500) occurring in the gypsum production step (S310). The two wastewater are put into the reaction tank at a ratio of about 1: 3.5 to 4.5 by stirring at room temperature for 1 to 3 hours so that the molybdenum in the wastewater can be precipitated in a molybdenum oxide state and recovered.

Hereinafter, in order to confirm the effectiveness of the process for producing molybdenum trioxide from the molybdenum concentrate of the present invention, the inventors of the present invention will explain the present invention in more detail through experiments and production using a pyrolysis plant. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

Example 1

1.4 ton of molybdenum concentrate (molybdenum concentrate) having a molybdenum content of 30% was mixed with 6 m ³ of water and slurry was added to a conversion tank containing 8 m ³ of a diluted nitric acid solution at 60 ° C, followed by stirring at 50 rpm at 90 ° C And the reaction was maintained for 20 hours. The pressure gauge in the reaction tank was continuously monitored so that the pressure did not exceed 1.2 bar. At this time, the concentration of the initial nitric acid diluting solution was adjusted so that the concentration of nitric acid in the reaction tank after the slurry was completely introduced was 12% You have to.

After the conversion reaction was completed, air was injected into the reactor and the solution was cooled for 4 hours. Then, the solidified liquid was separated to separate the conversion cake and the conversion filtrate.

For the conversion cake, 2 tones of the conversion cake containing the function were added to a washing tank containing 10 m ³ of water, stirred at 50 rpm at room temperature, stirred for 1 hour, washed and subjected to solid-liquid separation, The wash water was separated. After that, 2 tons of the converted cake was dropped into a dissolution tank containing 4 m ³ of water, stirred for 30 minutes so that the water and the converted cake were well mixed, and the pH was measured. While 25% ammonia water was added until the pH reached 8 The solution was kept at pH 8 and dissolved for 1 hour with stirring. After the dissolution reaction, solid-liquid separation was carried out to separate the ammonium molybdenum solution and the un-dissolved residue.

Conversion of the raw materials - Filtration - Washing - Ammonia dissolution - 5 m ³ of the ammonium molybdenum solution obtained through the filtration process is evaporated at 450 mmHg and 75 ° C for 12 hours in an evaporation tank. When it is concentrated to about 1.5 to 2 m ³ , molybdenum acid It is cooled to room temperature and separated from the solution by using a centrifuge. In this case, the solution is left in the evaporation tank and used again.

The ammonium molybdate separated from the centrifuge is dried in a preheater at 100 ° C for 1 hour to reduce water content to within 5%.

The dried ammonium molybdate was put into a fluidized-bed reactor heated to 500 ° C., deammonized and recovered as molybdenum trioxide.

The recovery rate can be increased in the step of recovering molybdenum from the process water generated in the subsequent process. As a process, the mixture of 5 m ³ of washing cake washing water and 5 m ³ of gypsum washing water and 10 m ³ of undiluted residue washing water were mixed and adjusted to pH 4 to maintain the reaction for 2 hours. When this method is used, ammonium molybdate is produced as a solid, and residual molybdenum in the wastewater can be recovered.

As a result, the recovery rate of molybdenum is over 95% due to the molybdenum oxide manufacturing process and the metal recovery process.

Example 2

1.4 tons of low-grade raw material (molybdenum concentrate) having a molybdenum content of 40% was mixed with 6 m ³ of water and slurry was added to a conversion reaction tank containing 8 m ³ of a nitric acid dilution solution at 60 ° C and stirred at 50 rpm at 90 ° C And the reaction is maintained for 20 hours. The pressure gauge in the reaction tank is constantly monitored so that the pressure does not exceed 1.2 bar. At this time, the concentration of the initial nitric acid diluting solution should be adjusted exactly so that the concentration of nitric acid in the reaction tank after the slurry is completely introduced is 15% do.

After the conversion reaction was completed, the reaction mixture was cooled for 4 hours while introducing air into the reaction tank, and then subjected to solid-liquid separation to separate the conversion cake and the conversion filtrate.

For the conversion cake, 2 tones of the conversion cake containing the function were added to a washing tank containing 10 m ³ of water, stirred at 50 rpm at room temperature, stirred for 1 hour, washed and subjected to solid-liquid separation, Respectively. Then, 2 tones of the converted cake were dropped into a dissolution tank containing 4 m ³ of water, stirred for 30 minutes so that the water and the converted cake were well mixed, and then the pH was measured while 25% ammonia water was added until the pH reached 8 maintained at pH 8 and dissolved for 1 hour with stirring. After the dissolution reaction, solid-liquid separation was carried out to separate the ammonium molybdenum solution and the un-dissolved residue.

As a result, the recovery rate of molybdenum by molybdenum oxide production process and crude metal recovery process is more than 96%.

Example 3

1.4 ton of molybdenum concentrate (molybdenum concentrate) with molybdenum content of 55% was mixed with 6 m ³ of water and slurry was added to a conversion reactor containing 8 m ³ of nitric acid dilution at 60 ° C and stirred at 50 rpm at 90 ° C And the reaction is maintained for 20 hours. The pressure gauge in the reaction tank is continuously monitored so that the pressure does not exceed 1.2 bar. At this time, the concentration of the initial nitric acid diluting solution should be exactly adjusted so that the concentration of nitric acid in the reaction tank after the slurry is fully charged may be 12 vol% do.

For the conversion cake, 2 tones of the conversion cake containing the function were added to a washing tank containing 10 m ³ of water, stirred at 50 rpm at room temperature, stirred for 1 hour, washed, separated by solid-liquid separation, Respectively. After that, 2 tons of the converted cake was dropped into a dissolution tank containing 4 m ³ of water, stirred for 30 minutes so that the water and the converted cake were well mixed, and the pH was measured. While 25% ammonia water was added until the pH reached 8 The solution was kept at pH 8 and dissolved for 1 hour with stirring. After the dissolution reaction, solid-liquid separation was carried out to separate the ammonium molybdenum solution and the un-dissolved residue.

As a result, the recovery rate of molybdenum is more than 98% due to the molybdenum oxide manufacturing process and the metal recovery process.

Examples 1 to 3 described above are summarized in Table 1 below.

Example 4

The low - grade molybdenum concentrate containing 30% molybdenum was used to proceed with the gypsum reaction using the conversion filtrate resulting from the conversion reaction. Prepare 12 m ³ in a gypsum bath and measure the SO ₄ ^2- concentration of the solution. The slurry lime slurry is filled with 1 m ³ of water and 300 kg of quick lime is poured from the lime slurry feed tank to prepare a slurry slurry. The prepared slaked lime slurry is put into a gypsum reactor, and stirring is performed at this time. The temperature of the gypsum reactor is maintained at 50 ° C, and the reaction is maintained for 2 hours after all of the slaked lime slurry is introduced. After solid-liquid separation, the solid gypsum was washed with 10 times water in a gypsum washing tank and then dried.

Example 5

The low - grade molybdenum concentrate containing 40% molybdenum was used to proceed the gypsum reaction using the conversion filtrate resulting from the conversion reaction. Prepare 12 m ³ in a gypsum bath and measure the SO ₄ ^2- concentration of the solution. After 1.4 m ³ of water is filled in the slurry slurry tank, 400 kg of quicklime is dropped from the slurry supply tank to prepare a slurry slurry. The prepared slaked lime slurry is put into a gypsum reactor, and stirring is performed at this time. The temperature of the gypsum reactor is maintained at 50 ° C, and the reaction is maintained for 2 hours after all of the slaked lime slurry is introduced. After solid-liquid separation, the solid gypsum was washed with 10 times water in a gypsum washing tank and then dried.

Example 6

The low - grade molybdenum concentrate containing 55% of molybdenum was used to proceed with the gypsum reaction using the conversion filtrate resulting from the conversion reaction. Prepare the solution in a gypsum tank at 12 m ³ and measure the SO ₄ ^2- concentration of the solution. The slurry is filled with 1.8 m ³ of water, and 550 kg of quicklime is poured from the quicklime feed tank to prepare slurry slurry. The prepared slaked lime slurry is put into a gypsum reactor, and stirring is performed at this time. The temperature of the gypsum reactor is maintained at 50 ° C, and the reaction is maintained for 2 hours after all of the slaked lime slurry is introduced. After solid-liquid separation, the solid gypsum was washed with 10 times water in a gypsum washing tank and then dried.

The amounts of calcium oxide and water supplied during the production of the slaked slurry of Examples 4 to 6 are summarized in Table 2 below.

Example quid pro quo quid pro quo
elegance Oil Raw material input method transform Dissolution Recovery rate One Low-grade molybdenum concentrate 30% 0.5% Slurrying input 12 vol% nitric acid solution,
Desulfurization at 90 ℃ ammonia
pH 8 95% 2 Low-grade molybdenum concentrate 40% One% Slurrying input 15 vol% nitric acid solution, desulfurization at 90 < 0 > C ammonia
pH 8.5 96% 3 High-grade molybdenum concentrate 55% 1.5% Slurrying input 20 vol% nitric acid solution, desulfurization at 90 < 0 > C ammonia
pH 8 98%

Conversion filtrate sulfuric acid concentration
(%) Quicklime dosage
(kg) Water volume
(m ³ ) 6 50 0.2 7 100 0.4 8 150 0.5 9 200 0.7 10 250 0.9 11 300 One 12 350 1.2 13 400 1.4 14 450 1.5 15 500 1.7 16 550 1.8 17 600 2 18 650 2.2 19 700 2.4 20 800 2.8 21 900 3

As described above, the present invention is characterized in that the molybdenum concentrate is treated in turn through a raw slurrying step, a conversion step, a cooling washing step, a dissolution step, a non-dissolved residue separation step, a concentrated evaporation step and a dry pyrolysis step, It is possible to effectively recover molybdenum trioxide of high purity from molybdenum concentrate by separating molybdenum by separating and using molybdenum by oxidizing the concentrate (MoS ₂ ) simultaneously with desulfurization.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be obvious to those of ordinary skill in the art.

10: Slurry of raw material 11: Conversion tank
12: aeration tank 13: absorption tower
14: NOx scrubber 15: Oxidizer 3
16: nitric acid adjusting tank 17: filter for exclusive use of conversion reaction
18: Plaster reactor 19: Dissolution tank
20: air reservoir 21: switch cake cleaning filter press
22: Washing water storage tank 23: Dissolution tank
24: Filter press for melting reaction tank 25: Vacuum concentration concentration evaporation tank
26: Centrifuge 27: preheater
28: fluidized-bed reactor 29: ammonia water regenerator
30: Ammonia scrubber 31: Mixture of MoS ₂ with gypsum filtrate or water
32: oxygen supplier 33: water (industrial water for aeration tank)
34: Polling 35: Nitric acid
36: Washing water 37: Water (industrial water for dissolving tank)
38: evaporated concentrate 39: ammonia water storage tank
40: conversion filtrate 41: gypsum filtrate
42: ammonia water 43: quicklime
44: slaked lime slurry (water + calcium lime) 45: filter press for gypsum process
46: Gypsum moisture dryer 47: Plaster
48: water + ammonia 49: sulfuric acid
50: heat exchanger 60: quicklime supply tank
61: slaked lime reaction tank

Claims

A conversion step of converting the molybdenum concentrate raw material into an oxide simultaneously with desulfurization with nitric acid;
A nitric acid regeneration step of regenerating NOx gas generated in the conversion step as nitric acid;
A cooling washing step of cooling and washing the acid component of the molybdate (Molybdate, H ₂ MoO ₄ , MoO ₃ ? XH ₂ O) oxide converted in the conversion step;
A gypsum producing step of removing gypsum from the conversion filtrate resulting from the conversion step and forming gypsum;
A nitrate regeneration step of adjusting the concentration of the solution generated in the nitrate regeneration step and the gypsum production step to a conversion step;
Dissolution step of dissolving the molybdenum oxide is converted cake washing in the washing step by cooling the ammonia water (NH ₄ OH) solution in the dissolution tank;
Removing undissolved residues remaining as residues in the dissolution step by washing with water, filtering the remaining undissolved residues from the dissolution reaction tank, and separating the undissolved residues;
(NH ₄ ) ₂ MoO ₄ ) is precipitated by evaporating the dissolved filtrate from which the unreacted residue has been separated under reduced pressure in a concentrated evaporator, and then recovered by filtration with a centrifugal separator;
A dry pyrolysis step of recovering molybdenum trioxide through moisture drying of the solid ammonium molybdate generated in the concentration and evaporation step and pyrolysis of ammonia;
An ammonia regeneration step of regenerating ammonia gas generated in the concentrating and drying pyrolysis step; And
And recovering valuable metals such as molybdenum and copper by precipitating from the process water generated in the cooling washing step, the gypsum production step and the un-dissolved residue separation step to a hydroxide state by controlling the pH, and a valuable metal recovery step Lt; RTI ID = 0.0 > molybdenum < / RTI > concentrate.

The process according to claim 1, wherein the molybdenum concentrate raw material is a molybdenum concentrate having an oil content of less than 2 vol% or a molybdenum concentrate slurry having an oil content of 2 to 7 vol%.

The slurry as claimed in claim 2, wherein the slurry is produced using water, or produced using the gypsum filtrate produced in the gypsum production step, or prepared using the solution obtained in the nitric acid adjustment step Molybdenum.

The method according to claim 1, wherein the nitric acid solution used in the conversion step is a nitric acid solution having a concentration of 10 to 30%
The conversion step is carried out in a temperature range of from 60 to 100 < 0 > C and a reaction pressure of from 0.5 to 1.2 bar,
Wherein the molybdenum concentrate raw material is fed at a rate of 9.3 to 12 L / min.

The method according to claim 1, wherein the nitric acid regeneration step comprises oxidizing the NOx in an oxidizer maintained at 100 to 400 ° C, regenerating the NOx by passing it through an aeration tank and a poling absorption tower, Wherein the gas is passed through a NOx scrubber to be completely removed and discharged to the atmosphere.

The method of claim 1, wherein the ammonia water (NH ₄ OH) solution to be used in the melting step is maintained at a temperature 5 to 40 ℃ and pH 7.5 to 8.5,
Wherein the dissolution is performed for 0.5 to 2 hours.

The method according to claim 1, wherein the concentrated evaporation step comprises removing the undissolved residue in the dissolution step and reducing the remaining solution to a pressure of 400 to 500 mmHg in a concentrated evaporation tank, Wherein the molybdenum trioxide is reacted for 20 hours.

8. The method according to claim 7, wherein the concentration and evaporation step is carried out without stirring and with agitation from the start of stirring.

The method of claim 8, wherein the stirring start time is in the range of 25% to 75% of the initial reaction time.

[3] The method of claim 1, wherein the drying in the dry pyrolysis step is performed by maintaining the solid ammonium molybdate generated in the concentration and evaporation step at a temperature of 80 to 100 DEG C for about 1 to 3 hours.

[10] The method of claim 10, wherein the pyrolysis in the drying pyrolysis step is carried out by transferring the dried ammonium molybdate to a fluidized-bed reactor, and then heating the air at 350 to 600 DEG C at a flow rate of 2 to 16 m / And then introducing the molybdenum trioxide into the fluidized bed reactor at a flow rate to form an ammonium molybdate fluidized bed.

The method according to claim 1, wherein the conversion filtrate generated in the conversion step used in the gypsum production step has a sulfuric acid concentration of 6 to 21%
The slurry slurry is added in a range of 50 to 1000 kg in the gypsum production step according to the sulfuric acid concentration in the conversion filtrate,
Wherein the gypsum production step is carried out by reacting at a temperature of 20 to 50 DEG C for 1 to 4 hours.

The method of claim 12 wherein the calcium hydroxide slurry of molybdenum trioxide, characterized in that the method prepared by mixing quicklime with water from 0.2 to 3 m ³ of 50 to 900 kg.

14. The method according to any one of claims 1 to 13, wherein the acidic solution generated in the cooling cleaning step or the acidic solution generated in the step of producing the gypsum, or a mixture thereof and the basic solution generated in the step of removing un- &Lt; / RTI > further comprising the step of mixing the molybdenum trioxide.

15. The method according to claim 14, wherein the mixing is performed by maintaining the stirring at room temperature for 1 to 3 hours so that the pH is 3.5 to 4.5.

14. The method according to any one of claims 1 to 13, wherein the step of measuring the amount of NOx gas generated in said converting step, or the step of analyzing the concentration of nitric acid generated in said converting step, &Lt; / RTI >

14. The method according to any one of claims 1 to 13, wherein the ammonia generated in the step of concentrating and evaporating, or the ammonia generated in the step of drying pyrolysis, or the ammonia generated in the step of condensing and evaporating and the step of drying pyrolysis, And a regeneration ammonia regeneration step of regenerating the molybdenum trioxide.