Treatment method of raffinate from full wet molybdenum smelting

Abstract

The present invention relates to a method for treating a fully wet molybdenum smelting raffinate, wherein a first calcium agent is added to the fully wet molybdenum smelting raffinate, and the reaction is stirred at 40-50°C, and the first mixed slurry is obtained after the end point pH value of the reaction system is 1-1.5 by controlling the addition amount of the first calcium agent; the first mixed slurry is subjected to solid-liquid separation to obtain dihydrate gypsum and a first liquid phase; a second calcium agent is added to the first liquid phase, and the reaction is stirred, and the end point pH value of the reaction system is 7-8 by controlling the addition amount of the second calcium agent, and the second mixed slurry is obtained; the second mixed slurry is subjected to solid-liquid separation to obtain gypsum slag and a second liquid phase. The method of the present invention can produce two kinds of neutralized slags such as dihydrate gypsum and gypsum slag, wherein the dihydrate gypsum slag produced can be sold to generate economic value, and only a small amount of gypsum slag is produced for storage, and the environmental protection and economic benefits are good.

Description

Technical Field

[0001] The invention relates to a method for treating fully wet molybdenum smelting raffinate, and belongs to the field of nonferrous metallurgy. Background Art

[0002] Traditional molybdenum smelting adopts a fire-wet combined process. Molybdenum concentrate is roasted to produce molybdenum roasted sand. The roasting flue gas uses low-concentration SO 2 Flue gas acid production, or adding pyrite roasting flue gas acid production, molybdenum roasted sand through ammonia leaching - purification - acid precipitation crystallization and other processes to produce ammonium molybdate, this method has roasting flue gas SO 2 There are many problems such as low concentration, high acid production cost, high molybdenum content in ammonia leaching residue (Mo 5-8%), low molybdenum leaching rate, poor purification and impurity removal effect, unstable product quality, etc. In order to overcome the shortcomings of the above-mentioned traditional molybdenum smelting technology, the full wet molybdenum smelting technology has been increasingly promoted and applied, that is, the molybdenum concentrate is subjected to oxygen pressure-alkali leaching-extraction-acid precipitation crystallization and other processes to produce ammonium molybdate. This method overcomes the shortcomings of traditional molybdenum smelting and has obvious technical advantages. Its characteristics are that it does not require flue gas acid production, is environmentally friendly, has low molybdenum content in alkali leaching residue (Mo<1%), has high molybdenum leaching rate, and has good product quality of extraction and crystallization. Since the oxygen pressure process converts sulfur in the molybdenum concentrate into sulfuric acid, the extraction is carried out under acidic conditions, and the raffinate produced contains sulfuric acid and heavy metal impurities, so it needs to be neutralized and impurity-removed.

[0003] In various industrial production, lime treatment is often used to treat waste liquid containing sulfuric acid. However, byproducts of lime treatment, such as phosphogypsum, fluorgypsum, desulfurized gypsum, and mirabilite gypsum, need to be further treated before they can be sold on the market. For sulfur-containing flue gas or acid-containing wastewater, lime treatment is generally used. The sulfur-containing flue gas undergoes two steps of absorption and oxidation. The lime slurry reacts with the SO in the flue gas. 2 The reaction occurs and is absorbed and converted into calcium sulfite or calcium bisulfite, and then air is introduced to oxidize it into dihydrate gypsum. The lime method can be used to treat sulfur-containing flue gas to obtain dihydrate gypsum for sale as a product, while the lime method is used to treat acidic wastewater. The lime slurry and H 2 SO 4 The reaction turns into gypsum slag. Since the wastewater contains heavy metal impurities, the heavy metals are deposited in the gypsum slag during the neutralization process. It cannot be sold as a product and can only be stored. In this way, although the wastewater is treated, a large amount of solid waste with low utilization value is generated, which is bound to lead to new problems. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an environmentally friendly and economical method for treating molybdenum smelting raffinate by a full wet process.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A method for treating a raffinate from a fully wet molybdenum smelting process comprises the following steps:

[0007] S1. Provide full wet molybdenum smelting raffinate;

[0008] Among them, the raffinate of the fully wet molybdenum smelting process contains [MoO 2 (SO 4 ) 2 ] 2- , H 2 SO 4 and impurity ions, wherein the impurity ions include Cu 2+ , Fe 3+ 、Zn 2+ 、Al 3+ 、As 3+ One or more of the following;

[0009] S2, adding a first calcium agent to the full wet molybdenum smelting raffinate, stirring and reacting at 40-50° C., and controlling the amount of the first calcium agent added so that the endpoint pH value of the reaction system is 1.1-1.6, to obtain a first mixed slurry;

[0010] Wherein, the first calcium agent includes CaO, CaCO 3 , Ca(OH) 2 One or more of the following;

[0011] S3, performing solid-liquid separation on the first mixed slurry to obtain dihydrate gypsum and a first liquid phase;

[0012] S4, adding a second calcium agent to the first liquid phase, stirring for reaction, and controlling the amount of the second calcium agent added so that the end point pH value of the reaction system is 7-8, thereby obtaining a second mixed slurry;

[0013] Wherein, the second calcium agent includes CaO, CaCO 3 , Ca(OH) 2 One or more of the following;

[0014] S5. Perform solid-liquid separation on the second mixed slurry to obtain gypsum slag and a second liquid phase.

[0015] Thus, by first adding the first calcium agent to the raffinate and controlling the reaction temperature and the pH value at the reaction end point, the acid in the raffinate can be partially consumed and the sulfate radical can be converted into dihydrate gypsum. At the same time, by controlling the pH to be acidic, Cu 2+ , Fe 3+ 、Zn 2+ 、Al 3+The metal ions are precipitated to obtain high-purity dihydrate gypsum, making it possible to sell dihydrate gypsum directly as a product, thereby improving economic benefits; then, a second calcium agent is added to the first liquid phase after separating the dihydrate gypsum, and the end point pH value is controlled to be 7-8, which can consume the remaining acid and convert sulfate into gypsum slag CaSO 4 At this time, heavy metal ions will also precipitate with gypsum slag, so that the concentration of heavy metal ions in the liquid phase is reduced. Since a large amount of sulfate ions are produced in the form of dihydrate gypsum that can be sold, and only a small amount of sulfate ions are produced in the form of gypsum slag, the amount of waste slag finally obtained by the present invention can actually be greatly reduced, the storage pressure of waste slag is effectively reduced, and the economic benefits can be effectively improved.

[0016] Further, in S1, H 2 SO 4 The concentration is 25-35 g / L, further 28-32 g / L.

[0017] Furthermore, the average particle size of the first calcium agent is 280-350 mesh; the average particle size of the second calcium agent is 280-350 mesh.

[0018] Furthermore, in S2, the end point pH value is 1.2-1.5.

[0019] Further, in S2, the reaction is stirred at 42-48°C.

[0020] Furthermore, in S2, the reaction time is 1-1.5 h; in S4, the reaction time is 1-1.5 h.

[0021] Furthermore, in S3, the first mixed slurry is firstly thickened to obtain a section of neutralized residue and a section of supernatant; the section of neutralized residue is then centrifugally filtered to obtain dihydrate gypsum and a first filtrate; the first filtrate and the section of supernatant are combined as a first liquid phase.

[0022] Furthermore, in S5, the second mixed slurry is firstly thickened to obtain the second-stage neutralization residue and the second-stage supernatant; the second-stage neutralization residue is then subjected to filter pressing to obtain gypsum residue and the second filtrate; the second filtrate and the second-stage supernatant are combined as the second liquid phase.

[0023] Furthermore, the second liquid phase is returned to the oxygen pressure leaching process of the fully wet molybdenum smelting.

[0024] Furthermore, in the fully wet molybdenum smelting raffinate, based on the concentration of Mo, [MoO 2 (SO 4 ) 2 ] 2- The concentration of Cu is 0.01-0.3g / L; 2+The concentration of Fe is 1-5g / L; 3+ The concentration of Zn is 1-5g / L; 2+ The concentration is 0.1-1g / L; Al 3+ The concentration of As is 0.1-1g / L; 3+ The concentration of H 2 SO 4 The concentration is 25-35g / L.

[0025] Furthermore, the full wet molybdenum smelting raffinate also contains ReO 4 - , ReO 4 - (Converted to Re concentration) is 0.001-0.2 mg / L. Re refers to the element rhenium.

[0026] The present invention adopts a two-stage lime treatment method, taking calcium carbonate as a calcium agent as an example, the main reaction of S2 is as follows:

[0027] CaCO 3 +H 2 SO 4 →CaSO 4 0.5H 2 O+0.5H 2 O+CO 2 ↑ (1)

[0028] CaSO 4 0.5H 2 O+1.5H 2 O→CaSO 4 ·2H 2 O (2)

[0029] The second stage controls the end point pH to 7-8, generating gypsum slag. The main reactions in S4 are as follows:

[0030] CaCO 3 +H 2 SO 4 →CaSO 4 +H 2 O+CO 2 ↑ (3)

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) In the present invention, the pH endpoint in S2 is controlled under weakly acidic conditions, which creates favorable conditions for the formation of hemihydrate gypsum and allows heavy metal ions to remain in the liquid phase without entering the slag phase. The quality of the obtained dihydrate gypsum product is high, and the purity of the dihydrate gypsum is greater than 90%;

[0033] (2) The raffinate of the fully wet molybdenum smelting process itself has a certain amount of waste heat. The reaction temperature in S2 is controlled to be 40-50°C, and the hemihydrate gypsum is heated to dissolve in water to generate dihydrate gypsum. The heat of the raffinate of the fully wet molybdenum smelting process itself can be used to complete the transformation of the gypsum crystal form, which has high heat utilization efficiency and helps save energy consumption;

[0034] (3) The pH in S4 is controlled at 7-8, and the residual acid and most of the heavy metals in the raffinate are converted into gypsum slag, thereby reducing the amount of waste slag; the neutralized liquid is returned to the previous oxygen pressure leaching process for recycling;

[0035] (4) Compared with the conventional one-stage lime method for treating acidic wastewater which can only produce gypsum slag, the method of the present invention can produce two types of neutralized slag, namely dihydrate gypsum and gypsum slag. Among them, the dihydrate gypsum slag produced is larger and can be sold to generate economic value, while only a small amount of gypsum slag is produced, which can be stored and treated, and has good environmental and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention discloses a flow chart of a method for treating a molybdenum smelting raffinate by a full wet process. DETAILED DESCRIPTION

[0037] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0038] Example 1

[0039] A method for treating a raffinate from a fully wet molybdenum smelting process comprises the following steps:

[0040] S1. Provide full wet molybdenum smelting raffinate;

[0041] Among them, the raffinate of the fully wet molybdenum smelting process contains [MoO 2 (SO 4 ) 2 ] 2- , Cu 2+ , Fe 3+ 、Zn 2+ 、Al 3+ 、ReO 4 - 、As 3+ and H 2 SO 4 The concentrations of various ions are shown in Table 1.

[0042] Table 1 Main components of the raffinate from fully wet molybdenum smelting

[0043]

[0044] S2, to 10m 3 Adding a first calcium agent to the raffinate of the fully wet molybdenum smelting process, stirring and reacting at 40° C. for 1 hour, and controlling the amount of the first calcium agent added so that the end point pH value of the reaction system is 1.3, thereby obtaining a first mixed slurry;

[0045] Wherein, the first calcium agent is calcium carbonate powder (CaO content is 53%, average particle size is 320 mesh); the total addition amount of the first calcium agent is 245kg;

[0046] S3, the first mixed slurry is subjected to solid-liquid separation to obtain 468 kg of dihydrate gypsum (water content is 10%) and 9.95 kg of the first liquid phase. 3 ;

[0047] S4, adding a second calcium agent to the first liquid phase, stirring and reacting for 1 hour, and controlling the amount of the second calcium agent added so that the end point pH value of the reaction system is 7, thereby obtaining a second mixed slurry;

[0048] Wherein, the second calcium agent is calcium carbonate powder (CaO content is 53%, average particle size is 320 mesh), and the total addition amount is 62kg;

[0049] S5, the second mixed slurry is subjected to solid-liquid separation to obtain 104 kg of gypsum slag (water content is 20%) and 9.93 m of the second liquid phase 3 .

[0050] In S3, the first mixed slurry is firstly thickened to obtain a section of neutralized residue and a section of supernatant; the section of neutralized residue is then centrifugally filtered to obtain dihydrate gypsum and a first filtrate; the first filtrate and the section of supernatant are combined as a first liquid phase.

[0051] In S5, the second mixed slurry is firstly thickened to obtain the second-stage neutralization slag and the second-stage supernatant; the second-stage neutralization slag is then subjected to filter pressing to obtain gypsum slag and the second filtrate; the second filtrate and the second-stage supernatant are combined as the second liquid phase and returned to the oxygen pressure leaching process of the fully wet molybdenum smelting.

[0052] After testing, the calcium sulfate content (on a dry basis) in the obtained dihydrate gypsum was 93%, meeting the requirements of GB / T 37785-2019 for secondary calcium sulfate dihydrate.

[0053] Example 2

[0054] A method for treating a raffinate from a fully wet molybdenum smelting process comprises the following steps:

[0055] S1. Provide full wet molybdenum smelting raffinate;

[0056] Among them, the raffinate of the fully wet molybdenum smelting process contains [MoO2 (SO 4 ) 2 ] 2- , Cu 2+ , Fe 3+ 、Zn 2+ 、Al 3+ 、ReO 4 - 、As 3+ and H 2 SO 4 The concentrations of various ions are shown in Table 2.

[0057] Table 2 Main components of the raffinate from fully wet molybdenum smelting

[0058]

[0059] S2, to 10m 3 Adding a first calcium agent to the raffinate of the fully wet molybdenum smelting process, stirring and reacting at 50° C. for 1.2 hours, and controlling the amount of the first calcium agent added so that the end point pH value of the reaction system is 1.5, thereby obtaining a first mixed slurry;

[0060] Wherein, the first calcium agent is calcium carbonate powder (CaO content is 53%, average particle size is 320 mesh); the total addition amount of the first calcium agent is 306 kg;

[0061] S3, the first mixed slurry is subjected to solid-liquid separation to obtain 585 kg of dihydrate gypsum (water content is 10%) and 9.94 m of the first liquid phase. 3 ;

[0062] S4, adding a second calcium agent to the first liquid phase, stirring and reacting for 1.2 hours, and controlling the amount of the second calcium agent added so that the end point pH value of the reaction system is 8, thereby obtaining a second mixed slurry;

[0063] Wherein, the second calcium agent is calcium carbonate powder (CaO content is 53%, average particle size is 320 mesh), and the total addition amount is 64kg;

[0064] S5, the second mixed slurry is subjected to solid-liquid separation to obtain 106 kg of gypsum slag (water content is 20%) and 9.92 m of the second liquid phase 3 .

[0065] In S3, the first mixed slurry is firstly thickened to obtain a section of neutralized residue and a section of supernatant; the section of neutralized residue is then centrifugally filtered to obtain dihydrate gypsum and a first filtrate; the first filtrate and the section of supernatant are combined as a first liquid phase.

[0066] In S5, the second mixed slurry is firstly thickened to obtain the second-stage neutralization slag and the second-stage supernatant; the second-stage neutralization slag is then subjected to filter pressing to obtain gypsum slag and the second filtrate; the second filtrate and the second-stage supernatant are combined as the second liquid phase and returned to the oxygen pressure leaching process of the fully wet molybdenum smelting.

[0067] After testing, the calcium sulfate content (on a dry basis) in the obtained dihydrate gypsum was 92%, meeting the requirements of GB / T 37785-2019 for secondary calcium sulfate dihydrate.

[0068] Comparative Example 1

[0069] A method for treating a raffinate from a fully wet molybdenum smelting process comprises the following steps:

[0070] S1. Provide full wet molybdenum smelting raffinate;

[0071] Among them, the composition of the raffinate from the full wet molybdenum smelting process is the same as that in Example 1.

[0072] S2, to 10m 3 The first calcium agent is added to the raffinate of the full wet molybdenum smelting process, and the reaction is stirred at 40° C. for 1 hour. The amount of the first calcium agent added is controlled so that the end point H of the reaction system is 2 SO 4 After the concentration of 1g / L is 15g / L, a first mixed slurry is obtained;

[0073] Wherein, the first calcium agent is calcium carbonate powder (CaO content is 53%, average particle size is 320 mesh); the total addition amount of the first calcium agent is 122kg;

[0074] S3, the first mixed slurry is subjected to solid-liquid separation to obtain 254 kg of hydrated gypsum (containing 10% water) and 9.97 m3 of the first liquid phase. 3 ;

[0075] S4, adding a second calcium agent to the first liquid phase, stirring and reacting for 1 hour, and controlling the amount of the second calcium agent added so that the end point pH value of the reaction system is 7, to obtain a second mixed slurry;

[0076] Wherein, the second calcium agent is calcium carbonate powder (CaO content is 53%, average particle size is 320 mesh), and the total addition amount is 186kg;

[0077] S5, the second mixed slurry is subjected to solid-liquid separation to obtain 312 kg of gypsum slag (water content is 20%) and 9.91 m of the second liquid phase 3 .

[0078] In S3, the first mixed slurry is firstly thickened to obtain a section of neutralized residue and a section of supernatant; the section of neutralized residue is then centrifugally filtered to obtain high-water gypsum residue and a first filtrate; the first filtrate and the section of supernatant are combined to form a first liquid phase.

[0079] In S5, the second mixed slurry is firstly thickened to obtain the second-stage neutralization slag and the second-stage supernatant; the second-stage neutralization slag is then subjected to filter pressing to obtain gypsum slag and the second filtrate; the second filtrate and the second-stage supernatant are combined as the second liquid phase and returned to the oxygen pressure leaching process of the fully wet molybdenum smelting.

[0080] It can be seen that S2 uses a stronger acid condition (end point H 2 SO 4 15g / L), will produce hydrated gypsum (CaSO 4 ·nH 2 O), and further needs to be heated and dehydrated by hydrothermal or autoclaving to be converted into dihydrate gypsum, which increases the energy consumption of the dehydration process.

[0081] The test showed that the calcium sulfate content (on a dry basis) in the obtained gypsum was 85%.

[0082] Comparative Example 2

[0083] A method for treating a raffinate from a fully wet molybdenum smelting process comprises the following steps:

[0084] S1. Provide full wet molybdenum smelting raffinate;

[0085] Among them, the composition of the raffinate from the full wet molybdenum smelting process is the same as that in Example 2.

[0086] S2, to 10m 3 The first calcium agent is added to the raffinate of the fully wet molybdenum smelting process, and the mixture is stirred and reacted at 50° C. for 1.2 hours, and the end point pH value of the reaction system is controlled to be 8 by controlling the amount of the first calcium agent added, thereby obtaining a first mixed slurry;

[0087] Wherein, the first calcium agent is calcium carbonate powder (CaO content is 53%, average particle size is 320 mesh); the total addition amount of the first calcium agent is 367kg;

[0088] S3, the first mixed slurry was concentrated and centrifuged to obtain 555kg of gypsum slag (containing 10% water), and the first liquid phase was produced. 3 Return to hydrometallurgical molybdenum smelting.

[0089] It can be seen that when S2 adopts alkaline conditions (end point pH 8), gypsum slag will be produced and dihydrate gypsum cannot be obtained. The gypsum slag contains heavy metals and can only be stored.

[0090] The results show that the calcium sulfate content (on a dry basis) in the obtained gypsum slag is 76%.

[0091] Comparative Example 3

[0092] Comparative Example 1 was repeated, except that in S2, the amount of the first calcium agent added was 180 kg, so as to control the end point pH value of the reaction system to 0.9, and obtain a first mixed slurry.

[0093] The result is: solid-liquid separation was performed on the first mixed slurry to obtain 356 kg of hyperhydrated gypsum (containing 10% water). After testing, the calcium sulfate content (on a dry basis) in the obtained hyperhydrated gypsum was 87%.

[0094] Comparative Example 4

[0095] Comparative Example 1 was repeated, with the only difference being that in S2, the amount of the first calcium agent added was 260 kg, so as to control the endpoint pH value of the reaction system to be 2.0, and obtain a first mixed slurry.

[0096] The result is: the first mixed slurry is subjected to solid-liquid separation to obtain 505 kg of hyperhydrated gypsum (containing 10% water). After testing, the calcium sulfate content (on a dry basis) in the obtained hyperhydrated gypsum is 81%.

[0097] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A method for treating a raffinate from a fully wet molybdenum smelting process, characterized in that: The steps include: S1. Provide full wet molybdenum smelting raffinate; Among them, the raffinate of the fully wet molybdenum smelting process contains [MoO2(SO4)2] 2- , H2SO4 and impurity ions, wherein the impurity ions include Cu 2+ , Fe 3+ 、Zn 2+ 、Al 3+ 、As 3+ One or more of the following; the concentration of H2SO4 in the raffinate of the fully wet molybdenum smelting process is 25-35g / L; S2, adding a first calcium agent to the full wet molybdenum smelting raffinate, stirring and reacting at 40-50° C. for 1-1.5 hours, and controlling the amount of the first calcium agent added so that the endpoint pH value of the reaction system is 1.1-1.3, to obtain a first mixed slurry; Wherein, the first calcium agent is one or more of CaO, CaCO3, and Ca(OH)2; S3, performing solid-liquid separation on the first mixed slurry to obtain dihydrate gypsum and a first liquid phase; S4, adding a second calcium agent to the first liquid phase, stirring for reaction, and controlling the amount of the second calcium agent added so that the end point pH value of the reaction system is 7-8, thereby obtaining a second mixed slurry; Wherein, the second calcium agent includes one or more of CaO, CaCO3, and Ca(OH)2; S5. Perform solid-liquid separation on the second mixed slurry to obtain gypsum slag and a second liquid phase.

2. The processing method according to claim 1, characterized in that: The average particle size of the first calcium agent is 280-350 mesh; the average particle size of the second calcium agent is 280-350 mesh.

3. The processing method according to claim 1, characterized in that: In S2, the end point pH is 1.2-1.

3.

4. The processing method according to claim 1, characterized in that: In S2, the reaction was stirred at 42-48°C.

5. The processing method according to claim 1, characterized in that: In S4, the reaction time is 1-1.5 h.

6. The processing method according to claim 1, characterized in that: In S3, the first mixed slurry is firstly thickened to obtain a section of neutralized residue and a section of supernatant; the section of neutralized residue is then centrifugally filtered to obtain dihydrate gypsum and a first filtrate; the first filtrate and the section of supernatant are combined as a first liquid phase.

7. The processing method according to claim 1, characterized in that: In S5, the second mixed slurry is firstly thickened to obtain the second-stage neutralization residue and the second-stage supernatant; the second-stage neutralization residue is then subjected to filter pressing to obtain gypsum residue and the second filtrate; the second filtrate and the second-stage supernatant are combined to form the second liquid phase.

8. The processing method according to any one of claims 1 to 7, characterized in that: In the fully wet molybdenum smelting raffinate, according to the concentration of Mo, [MoO2(SO4)2] 2- The concentration of Cu is 0.01-0.3g / L; 2+ The concentration of Fe is 1-5g / L; 3+ The concentration of Zn is 1-5g / L; 2+ The concentration is 0.1-1g / L; Al 3+ The concentration of As is 0.1-1g / L; 3+ The concentration is 0.1-1mg / L.

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