JPS6136058B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for separately recovering molybdenum, uranium, and vanadium from coexisting materials such as ores or chemical precipitates. Naturally occurring molybdenum and uranium ores often contain molybdenum, uranium, and vanadium, although the amounts vary. However, there are currently few reports on the separate recovery of molybdenum, uranium, and vanadium contained in the leachate obtained by leaching ores with sulfuric acid. Generally, when coexisting molybdenum, uranium, and vanadium are leached out and molybdenum, uranium, and vanadium are separated and recovered from the leachate, it is better to separate and recover uranium first. The coprecipitation method, foaming separation method, adsorption method, and solvent extraction method are known as methods for recovering uranium. It is also used in crude smelting and refining plants. However, the forms of molybdenum, uranium, and vanadium are Mo (~), U (~), (~
Because they have many similar properties, precipitation separation by direct neutralization is difficult. Furthermore, if the concentration of molybdenum is higher than that of uranium or vanadium, contamination of molybdenum with uranium cannot be avoided. For example, if a coexistence of molybdenum, uranium, and vanadium is leached with sulfuric acid and an alkaline agent is added to the leachate to neutralize it, uranium will almost completely precipitate at pH 6, but vanadium will also precipitate slightly at pH 4. Molybdenum hardly precipitates, but when the molybdenum concentration is high, there is considerable contamination.
In addition, in the reduced state, molybdenum, uranium,
Some of the vanadium precipitates and is difficult to separate. From an analytical chemical standpoint, chemicals added to coprecipitate uranium include ferric salts such as ferric chloride or ferric ammonium sulfate, and aluminum salts such as aluminum sulfate or aluminum phosphate. However, molybdenum and vanadium may also precipitate due to pH adjustment, which is not appropriate. Furthermore, as a foaming separation method, foaming separation of uranium in seawater was attempted using surfactants such as soda soap, sodium lauryl sulfate, and laurylamine acetic acid. Adsorption of uranium by ferric iron, iron sulfide, titanic acid, or various metal soaps as organic adsorbents has also been reported, but it is difficult to apply any of these to sulfuric acid acidic solutions containing uranium, molybdenum, and vanadium. On the other hand, although there are examples of separation of molybdenum and vanadium through direct separation using ion-exchange resins, it is difficult to separate molybdenum, uranium, and vanadium-containing liquids using cationic and anionic exchange resins, and it is particularly unclear for molybdenum and uranium. . Furthermore, in extraction separation using organic solvents, uranium and molybdenum exhibit similar behavior, and are extracted in the same way at pH values below 0.5, and although separation from vanadium is possible to some extent, it is difficult to completely separate them. There are also examples of using solvent extraction as a crude separation; for example, after extracting molybdenum, uranium, and vanadium using a tertiary amine, uranium is back-extracted with sodium chloride, and then molybdenum is back-extracted with sodium carbonate. However, vanadium is mixed into the uranium cake, and uranium and vanadium are mixed into the molybdenum precipitate, making separation difficult. Particularly when the concentration of molybdenum in the leachate is 10 to 30 times higher than that of uranium or vanadium, any method for separating uranium alone is difficult to separate due to the influence of molybdenum. Therefore, it is extremely difficult to separately recover uranium from the above-mentioned three-component mixture, and currently no noteworthy method has been found. As a result of various long-term studies, the present inventors discovered a method of leaching using hydrochloric acid to first separate uranium from dissolved molybdenum, uranium, and vanadium. This made it possible to recover vanadium either as a raw material or as a product. That is, the present invention leaches molybdenum, uranium, and vanadium coexisting materials such as ores or chemical precipitates with hydrochloric acid, and removes molybdenum, uranium, and vanadium dissolved in the leachate.
Of vanadium, uranium is first removed as uranyl chloride (uranium chloride or oxide, or a mixture of both), then molybdenum is separated as sulfide, and finally vanadium is separated as hydroxide. The method provides a method for recovering molybdenum, uranium, and vanadium, and more specifically, a first step in which coexisting substances containing molybdenum, uranium, and vanadium are leached using hydrochloric acid and the leaching residue is separated, and an oxidizing agent is added to the liquid obtained in the first step. The second step consists of an additional oxidation step and an alkali agent addition step to adjust the pH.The third step consists of heating the liquid obtained in the second step for a certain period of time and then cooling it to separate the deposited precipitate. Add hydrochloric acid to the precipitate obtained in the step to dissolve it, then add an alkaline agent to adjust the pH and separate the formed precipitate.The fourth step is to add calcium hydroxide to the liquid obtained in the third step to adjust the pH. A fifth step of separating the precipitate produced by the adjustment; a sixth step of dissolving the precipitate obtained in the fifth step with sulfuric acid and separating the produced precipitate;
The seventh step is to add sulfuric acid to the liquid obtained in the fifth step and separate the precipitate, the eighth step is to add a sulfurizing agent to the liquid obtained in the sixth step and separate the formed precipitate. a ninth step of adding an alkaline agent to the liquid obtained in the eighth step to adjust the pH and separating the generated precipitate; and a ninth step of separating the precipitate produced by adding an alkaline agent to the liquid obtained in the eighth step. It is something. The present invention will be explained in detail below. [About the first step] In this step, crushed ore or chemical precipitates containing molybdenum, uranium, and vanadium are leached out at room temperature using 4N or higher hydrochloric acid.
Leaching is carried out at normal pressure, and after over-separation, if necessary, the entire amount of the residue is leached repeatedly. At this time, if the hydrochloric acid concentration during leaching is 2N or more, the leaching rate of Mo, U, and V will be almost 100%, but since the acid concentration affects the formation of uranium precipitation in the second and third steps described later, 4N The above is appropriate. Figure 1 shows the relationship between hydrochloric acid concentration and uranium precipitation rate. As can be seen from the results in Figure 1, 4N or more
Up to 6N is preferable, and too high a pressure is not preferable for economical reasons or excessive operation. Furthermore, by using hydrochloric acid, there is no precipitation of gypsum due to calcium contained in the coexisting substances, and the amount of leaching residue can be reduced, and the amount of uranium remaining in the residue can be kept to a minimum. [Regarding the second step] Hydrogen peroxide is added to the obtained leachate to oxidize it, and then calcium carbonate or calcium hydroxide is added to adjust the pH to 0.5 to 2.0, preferably 1.0 to 1.5. The order of addition may be in any order, but it is preferable to adjust the pH in advance with an alkaline agent.
It is best to add an oxidizing agent after raising the pH to about 0.5, and finally adjust it to a specific pH using an alkaline agent.
If the Mo concentration in the leachate is high, a pH of 2.0 will cause precipitation, so it is necessary to adjust the pH to around 1.5. Mo, U, at each pH during uranium precipitation
The relationship between the residual concentration of V is shown in FIG. However, the heating temperature was 80°C for 30 minutes. The amount of hydrogen peroxide added can be easily judged by the degree of color change. If you stop adding hydrogen peroxide when it becomes orange-yellow, Mo and V will change to Mo and V, respectively.
(), V(), making it difficult to form a precipitate. Also,
Although considerable heat of neutralization is generated by the addition of the alkali agent, the heating operation in the third step requires only slight heating due to this heat of neutralization. Note that instead of hydrogen peroxide, persulfuric acid, chlorine, hypochlorite, chlorate, or a compound such as oxyrite which produces hydrogen peroxide upon contact with water can be used. Although sodium hydroxide can be used as the alkaline agent, calcium hydroxide or calcium carbonate is preferable in order to recover hydrochloric acid and repeat the leaching step in the seventh step described below. [Regarding the third step] It is necessary to heat the liquid obtained in the second step above to 70°C or higher, but since neutralization heat is generated due to the addition of the alkaline agent in the second step, it is not necessary to heat it that much. , is very advantageous. PH1.5,
Figure 3 shows the relationship between heating temperature and uranium precipitation during hydrogen peroxide addition and overnight cooling. The heating time is preferably 30 to 90 minutes, preferably 30 to 60 minutes; if the heating is too long, Mo will precipitate, so it is necessary to limit the heating time. Figure 4 shows the relationship between heating time and the precipitation of Mo, U, and V. For cooling after heating for a certain period of time, either air cooling or water cooling may be used.
With water cooling, the time can be further reduced. Next, Figure 5 shows the various temperatures and residual uranium concentrations during uranium precipitation produced at a pH of 1.0 and a temperature of 80°C. At this time, let it cool for 3 hours until it reaches 20℃, then 10℃.
The reaction was carried out with water cooling until the temperature reached 5°C, and with ice cooling until the temperature reached 5°C. The uranium precipitate produced was very permeable and could be purified in a short period of time. [About the 4th step] In the step of refining the uranium precipitate obtained in the 3rd step, the precipitate is dissolved in hydrochloric acid and then neutralized with sodium hydroxide to a pH of 6 to 7, thereby reducing the contamination of molybdenum, etc. uranium can be recovered as U ₃ O ₈ (OH) ₂ . At this time, aqueous ammonia or calcium hydroxide may be used as the alkaline agent instead of sodium hydroxide. PH when producing uranium precipitation at each PH
FIG. 6 shows the relationship between the concentration and the residual concentration in the liquid. [About the 5th step] Calcium hydroxide is added to the liquid from which uranium was removed in the 3rd step to adjust the pH to 9 to 10, and molybdenum and vanadium are precipitated as hydroxides. The relationship between the PH and the residual concentration in the liquid when forming molybdenum and vanadium precipitates at each PH is shown in the seventh section.
As shown in the figure. [About the 6th step] The molybdenum and vanadium precipitates obtained in the 5th step are dissolved using sulfuric acid. At this time, in the fifth step, since calcium is present in the precipitate due to the use of calcium hydroxide, gypsum is precipitated and over-separated. The concentration of sulfuric acid added for dissolution is the concentration of free sulfuric acid suitable for the action of the sulfurizing agent in the 8th step below.
50g/or more. [Regarding the seventh step] In the fifth step, calcium hydroxide is added to precipitate molybdenum and vanadium as hydroxides, sulfuric acid is added to the separated liquid, and calcium ions in the liquid are recovered as gypsum. The liquid from which the gypsum is removed becomes a hydrochloric acid solution, which can be repeated in the first step as a leachate. [About the 8th step] The free sulfuric acid concentration of the liquid obtained in the 6th step is 50
g/ or more. Figure 8 shows the relationship between free sulfuric acid concentration and molybdenum sulfide production rate. Temperature must be 40℃ or higher, preferably 60-80℃
After heating to ℃, hydrogen sulfide gas is introduced to separately separate molybdenum in the liquid as molybdenum sulfide. At temperatures below 40°C, the amount of molybdenum sulfide produced is small, and higher temperatures are more advantageous in terms of transient properties. FIG. 9 shows the relationship between the reaction temperature and the production rate of molybdenum sulfide. In a strong sulfuric acid solution, molybdenum
It exists as MoO ₂ SO ₄ and is thought to react with hydrogen sulfide as shown in the following equation to produce molybdenum sulfide. MoO ₂ SO ₄ +3H ₂ S→MoS ₂ +H ₂ SO ₄ +2H ₂ O+S
Since a small amount of hydrogen sulfide exhibits a blue color and does not form a precipitate, by supplying a sufficient amount of 3 equivalents or more as shown in the above reaction formula, a dry black precipitate is gradually formed. Furthermore, vanadium ions in the leachate exist as VO ⁺ ₂ in a strongly acidic region, and are colorless, but may be yellow to orange as polyacids, and are reduced by hydrogen sulfide to become VO 2+ and V ³⁺ . At this time, if the vanadium concentration is high because hydrogen sulfide is consumed, hydrogen sulfide gas is used to recover molybdenum as molybdenum sulfide, taking into account the amount of dissolved molybdenum and vanadium and the solubility of hydrogen sulfide gas in the liquid at the reaction temperature. Quantity is required. Naturally, in this case, it is better for the reaction vessel to be highly airtight, and if the reaction is carried out under pressure, molybdenum sulfide can be quantitatively precipitated and the recovery rate can be further improved. Note that instead of hydrogen sulfide gas, hydrogen sulfide water, sodium hydrogen sulfide, sodium sulfide, or other elemental sulfur, sulfide, etc. that react with free acid to generate hydrogen sulfide can be used. The molybdenum sulfide obtained in this step can be purified and recovered as molybdenum trioxide. [About the 9th step] The liquid from which molybdenum was separated in the 8th step is in a reduced state, and when this liquid is neutralized with an alkaline agent such as sodium hydroxide, calcium hydroxide, calcium carbonate, etc., vanadium and residual molybdenum are reduced from pH 5 to 6. begins to precipitate, and most of the molybdenum precipitates at pH 9-10. Figure 10 shows the relationship between the pH and the concentration remaining in the solution when precipitating hydroxides during neutralization of vanadium and molybdenum in a reduced state. At this time, some molybdenum is mixed in, so it is necessary to purify it, but the recovered vanadium hydroxide can be made into a product by calcining it as vanadium pentoxide. As described above, the present invention is an extremely useful method that allows molybdenum, uranium, and vanadium to be separately recovered and manufactured into products more efficiently than coexisting molybdenum, uranium, and vanadium. Example Molybdenum, uranium, and vanadium having the composition shown in Table 1 were separated and recovered.

[Table] Chemical precipitation in Table 1 using 500ml of 6N hydrochloric acid solution
50g was leached for 1 hour at room temperature. The composition and leaching rate of the leachate are shown in Table 2.

[Table] The composition of 0.5 g of the obtained residue is shown in Table 3.

[Table] Next, calcium hydroxide was added to the leachate obtained in Table 2 to adjust the pH to 1.5, then hydrogen peroxide was added until the liquid turned yellow, and while heating to 70°C or higher, The mixture was stirred for 1 hour and left to cool overnight. After cooling,
The precipitate was separated, washed and dried, and the composition is shown in Table 4. The amount of precipitate deposited was 2.0 g.

[Table] The precipitation rate of uranium from the leachate is 97% as shown in the lower part of Table 4, but due to the high Mo concentration in the leachate, some Mo has co-precipitated, and the precipitation rate is It was 2% in the liquid. Further, the uranium precipitate shown in Table 4 was dissolved in hydrochloric acid, hydrogen peroxide was added (+600 mV or more), and the solution was neutralized with sodium hydroxide and recovered as a uranate containing less molybdenum. Next, Table 5 shows the liquid composition of 825 ml of the liquid from which the uranium precipitate was separated.

[Table] Calcium hydroxide was added to 825 ml of the liquid in Table 5 above to adjust the pH to 10, and the composition of the 60.6 g of precipitate after separating the formed precipitate is shown in Table 6.
The composition of ml is shown in Table 7.

[Table] As shown in Table 6, Mo: 93% and V: 98% or more were recovered.

[Table] Sulfuric acid was added to the solution obtained in Table 7 to precipitate gypsum, and when separated, the gypsum contained almost no Mo, U, and V, and pure white gypsum was recovered. The composition of 800 ml of the liquid at that time is shown in Table 8. In addition, the liquid shown in Table 8 can be repeated as a leaching liquid.

[Table] Next, Table 9 shows the composition of a solution 1.15 obtained by dissolving 60 g of Mo and V hydroxides shown in Table 6 in sulfuric acid and washing the gypsum produced at that time.

[Table] After heating the solution 1.15 in Table 9 to 80°C, hydrogen sulfide gas was passed through it at a flow rate of 1.0/min for 60 minutes, the hydrogen sulfide gas was stopped, and stirring was continued until it was allowed to cool. Table 10 shows the composition of the dried product after removing the molybdenum sulfide produced. The molybdenum sulfide production rate from Table 9 was 89%.

[Table] Table 11 shows the composition of liquid 1.3, excluding molybdenum sulfide.

[Table] When the Mo removal solution shown in Table 11 was neutralized with sodium hydroxide and adjusted to pH 10, the resulting precipitate was separated, and 2.8 g of the precipitate contained 17.7% vanadium. The composition of the liquid at this time is shown in Table 12.

[Table] Finally, this liquid is sent to the wastewater treatment process. As described above, molybdenum, uranium, and vanadium can each be recovered and concentrated as precipitates, and each metal can be recovered from these precipitates.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between hydrochloric acid concentration and uranium precipitate formation rate, Figure 2 is a graph showing the behavior of Mo, U, and V at each pH during uranium precipitation formation.
The figure is a graph showing the relationship between heating temperature and uranium precipitation.
Figure 4 is a graph of the relationship between heating time and the formation of Mo, U, and V precipitates. Figure 5 is a graph of the relationship between residual U concentration at each temperature when uranium precipitates are formed. Figure 6 is a graph of the relationship between heating time and the formation of uranium precipitates. Figure 7 is a graph showing the relationship between the PH and the concentration of residual U in the liquid.
A graph of the relationship between PH and the residual concentration in the liquid. Figure 8 is a graph of the relationship between the free sulfuric acid concentration and the production rate of molybdenum sulfide when hydrogen sulfide gas is blown into the liquid to precipitate molybdenum sulfide. Figure 9 is the same. A graph of the relationship between the reaction temperature and the production rate of molybdenum sulfide when hydrogen sulfide gas is blown into the liquid to precipitate molybdenum sulfide. Figure 10 shows the precipitation of each hydroxide in the neutralization of vanadium and molybdenum in a reduced state. when letting
The relationship graph between PH and residual concentration in the liquid, FIG. 11, is a process diagram of the method of the present invention.

Claims (1)

[Claims] 1. A first step in which a coexisting material containing molybdenum, uranium, and vanadium is leached using hydrochloric acid with a concentration of 4N or more and the leaching residue is separated, and an oxidizing agent is added to the liquid obtained in the first step. The second step consists of an additional oxidation step and a pH adjustment step by adding calcium hydroxide or calcium carbonate as an alkaline agent.The liquid obtained in the second step is heated for a certain period of time, stirred, and then cooled to form a precipitate. The third step is to separate the
After adding hydrochloric acid to the precipitate obtained in the step and dissolving it, add sodium hydroxide to adjust the pH to 6 to 7 and separate the generated precipitate.The fourth step is to add calcium hydroxide to the liquid obtained in the third step. Neutralize by adding
A fifth step of adjusting to ~10 and separating the generated precipitate,
The precipitate obtained in the fifth step has a free sulfuric acid concentration of 50 g/
A 6th step in which sulfuric acid is added to dissolve the solution and the precipitate precipitated at that time is separated; a 7th step in which sulfuric acid is added to the liquid obtained in the 5th step and the precipitate precipitated is separated; an eighth step of adding a sulfurizing agent to the liquid to be reacted and separating the generated precipitate;
Add the liquid obtained in the 8th step to neutralize it to pH 9-10.
A method for the fractional recovery of valuable metals for separately recovering molybdenum, uranium, and vanadium from the above-mentioned coexisting materials, the method comprising: a ninth step of separating the precipitate produced by adjusting the method. 2 The oxidizing agent used in the second step is one or two selected from compounds that generate hydrogen peroxide when in contact with water, such as hydrogen peroxide, chlorine, hypochlorite, chlorate, or oxylit. 2. A method for separating and recovering valuable metals according to claim 1, in which the amount of valuable metals is more than 100%. 3 The amount of oxidizing agent used in the second step is such that the molybdenum and panadium in the leachate are completely converted to Mo().
3. The method for separating and recovering valuable metals according to claim 1 or 2, wherein the pH value is adjusted to 1.0 to 1.5 by adding an alkali agent. 4. Claim 1, wherein the heating temperature in the third step is 70°C or higher, and the heating and stirring time is 30 to 60 minutes.
Separate recovery method for valuable metals as described in section. 5. The method for separating and recovering valuable metals according to claim 1 or 4, wherein the cooling method in the third step is cooling for at least 5 hours. 6. The method for separating and recovering valuable metals according to claim 1, wherein the liquid from the seventh step is repeated as a leachate in the first step. 7 The sulfurizing agent in the eighth step is one or more selected from hydrogen sulfide, sodium hydrogen sulfide, sodium sulfide, and elemental sulfur and sulfides that react with free acids to generate hydrogen sulfide. Range 1
Separate recovery method for valuable metals as described in section. 8. The method for separating and recovering valuable metals according to claim 1, wherein the alkaline agent used in the ninth step is at least one of sodium hydroxide, calcium hydroxide, and calcium carbonate. 9 The precipitate produced in the third step is uranium chloride or oxide, or a mixture of both, the precipitate produced and recovered in the fourth step is uranate, and the precipitate produced in the fifth step is molybdenum. It is vanadium hydroxide, the precipitate produced in the 6th and 7th steps is gypsum, and the liquid obtained in the 6th step is hydrochloric acid, which is repeated to the leaching step and the precipitate produced and recovered in the 8th step. The substance is molybdenum sulfide, and the precipitate produced and recovered in the ninth step is vanadium hydroxide.Claims 1, 2, 3, and 4
A method for separating and recovering valuable metals as described in Section 5, Section 5, Section 6, Section 7, or Section 8.