CN1760381A

CN1760381A - Technique for producing ammonium paratungstate from raw material of tungsten through iron exchange method of alkali breakdown

Info

Publication number: CN1760381A
Application number: CNA2004100468338A
Authority: CN
Inventors: 赵中伟; 李洪桂
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2004-10-13
Filing date: 2004-10-13
Publication date: 2006-04-19
Anticipated expiration: 2024-10-13
Also published as: CN1300350C

Abstract

A process for preparing ammonium paratungstate from tungsten ore by alkali decomposing-ironic exchange method includes such steps as adding tungsten ore in NaOH solution, alkali decomposing, ionic exchange, concentrating the exchanging liquid to educe out NaCl, and alkali decomposing of the alkaline mother liquid contain AsO4 ions, SiO3 ions, PO4 ions and WO4 ions while adding Ca(OH)2 for solidifying them. Its advantages are no drainage of sewage and high effect to recover NaOH, NaCl and WO3.

Description

Process for producing ammonium paratungstate by tungsten mineral raw material alkali decomposition-ion exchange method

The invention relates to the field of tungsten metallurgy, in particular to a process flow for producing Ammonium Paratungstate (APT) by a tungsten mineral raw material alkali decomposition-ion exchange method.

Background artthe existing processes for producing Ammonium Paratungstate (APT) by alkali decomposition-ion exchange of tungsten mineral raw materials are open (see fig. 1), and mainly comprise alkali decomposition of tungsten mineral raw materials and ion exchange of decomposed liquid to produce ammonium paratungstate. The ion exchange liquid in the production process is directly discharged as industrial wastewater, and the ion exchange liquid contains arsenic1 to 3mg/l, NaOH about 5 to 10g/l, WO₃About 0.05-0.01 g/l NaCl and about 8-10 g/l NaCl, which causes environmental pollution and valuable elements such as NaOH and WO₃According to incomplete statistics, the loss of NaOH caused by the loss reaches 2-3 ten thousand tons every year in China, and WO is₃Up to over 100 tons.

The invention provides a process for producing APT (alkaline decomposition tungsten mineral raw material) by ion exchange, which is free of waste water discharge, and aims to solve the problems that in the process of producing APT by a tungsten mineral raw material alkaline decomposition-ion exchange method, the direct discharge of an after-exchange liquid pollutes the environment and wastes useful resources.

The principle of the invention will be described first and then the process flow will be described.

The core of the invention is to return the post-hybridization solution to alkali decomposition, but two key problems should be solved for realizing the return of the post-hybridization solution:

1. in the decomposition process, harmful impurities As and SiO in the recycled NaOH-containing post-treatment liquid can be removed₂And P is solidified to enter the alkali decomposition slag, so that the continuous enrichment of As, Si and P in the leaching solution is avoided, and the quality of the final product is influenced. During the alkali decomposition, when CaWO exists in the system₄When present, CaWO₄Decomposed by NaOH to produce Ca (OH)₂And Ca (OH)₂Arsenic and silicon in the solution can be solidified, namely:

practice proves that when the calcium content in the raw material exceeds about 5 percent, PO in the solution₄ ^3-、AsO₄ ^3-、SiO₃ ^2-The curing rate can reach 85-95%.

2. And (3) separating NaOH from NaCl in the circulating mother liquor. The solubility of NaCl in concentrated NaOH solutions is very low, for example at 30 ℃ when the NaOH concentration is 408.9g/l and 564.4g/l, respectively, and the solubility of NaCl is 66.8g/l and 25.4g/l, respectively. Therefore, after the mixed solution containing NaOH and NaCl is concentrated to a certain degree, most NaCl is separated out and separated from NaOH, and the NaCl-removed NaOH solution can be returned to alkali for decomposition without bringing adverse effect on the ion exchange process of the subsequent process.

The present invention is thus realized in accordance with the principles setforth above.

The method comprises adding NaOH into tungsten raw material to decompose tungsten into Na₂WO₄The form enters into coarse Na₂WO₄Solution, while small part of arsenic, silicon and phosphorus in the raw material also enter the solution, and crude Na₂WO₄Ion exchange of the solution to obtain pure (NH)₄)₂WO₄Solution and post-hybridization solution, pure (NH)₄)₂WO₄The solution is sent to the preparation of Ammonium Paratungstate (APT), and the solution after the exchange contains NaOH, NaCl and WO₄ ^2-And AsO₄ ^3-、PO₄ ^3-、SiO₃ ^2-Concentrating the mixed solution until the concentration of NaOH is 400-; containing AsO₄ ^3-、PO₄ ^3-、SiO₃ ^2-The alkali mother liquor is returned to alkali decomposition, and P, As and Si are separated by Ca (OH) in the alkali decomposition process₂The solidification enters the slag, enrichment cannot occur, and the whole process realizes closed circulation of water.

The tungsten mineral raw material comprises scheelite concentrate containing more than or equal to 5 percent of Ca, wolframite and scheelite bulk concentrate containing more than or equal to 5 percent of Ca, and refractory tungsten middling with grade more than or equal to 15 percent.

When the content of calcium in the treated tungsten raw material is less than 5 percent, Ca (OH) can be added₂Or white tungsten concentrate to make Ca more than or equal to 5 percent.

Compared with the traditional alkali decomposition-ion exchange process, the invention has the advantages of good ① environmental benefit, no discharge of waste water containing harmful substances of arsenic, silicon and phosphorus, good ② economic benefit,valuable substances NaOH, NaCl and WO₃The ③ process is simple and easy to implement.

Drawings

FIG. 1: a classic process for producing APT by tungsten mineral raw material alkali decomposition-ion exchange;

FIG. 2: the invention relates to a principle process for producing APT.

Detailed Description

Example 1 referring to the post-crosslinking liquid components in the case of treating scheelite middlings having a high impurity content by an alkali decomposition-ion exchange method in China (generally, the relative content of NaCl/NaOH is 1.5 to 1, As/NaOH is 0.0005 to 0.001, Si/NaOH is 0.005 to 0.01, P/NaOH is 0.005 to 0.01, and WO/NaOH is 0.005 to 0.01)₃0.005/NaOH), an artificial post-mix solution was prepared with NaCl/NaOH 1, As/NaOH 0.0008, Si/NaOH 0.008, P/NaOH 0.001, WO₃The post-industrial liquor was concentrated to NaOH461g/l and NaCl was precipitated with NaOH 0.005 and the final alkaline mother liquor contained 34.8g/l NaCl, 0.35g/l As and 3.65g/l Si (considering PO)₄ ^3-Is a useful additive during alkaline decomposition, so the behavior of phosphorus during concentration was not examined).

92% NaOH, 90.5% silicon, 87.5% arsenic, 92% phosphorus, 75% WO in the post-crosslinking solution₃The solution was retained in the alkali mother liquor, and 90% NaCl was precipitated.

Example 2 20L of post-exchange liquor was collected from a tungsten metallurgical plant in China, wherein the relative components were NaCl/NaOH 1.41, As/NaOH 0.001, Si/NaOH 0.009, P/NaOH 0.007, and WO₃Concentrating and crystallizing 0.0035/NaOH to separate NaOH and NaCl to obtain solid NaCl and alkali mother liquor containing 484g/l NaOH, 50.1g/l NaCl, 3.64g/l Si, 0.36g/l As, and WO₃1.38g/l, 90% of total NaOH, 89% of total silicon, 85.3% of total arsenic and total WO₃76.8% of the amount goes to the caustic mother liquor.

EXAMPLE 3W-containing tungsten mineral feedstockO₃61.5%, Ca 6.05%, As 0.45%, Si 6.82%, 500g by weight, alkali decomposition was carried out at 160 ℃, the amount of alkali was 2.5 times of the theoretical amount, wherein 1.5 times the circulating alkali mother liquor of example 2, 1.0 times the amount of newly added solid alkali (corresponding to the theoretical amount of consumption of the reaction), after the reaction, filtration was carried out, the decomposition mother liquor was subjected to a conventional anion exchange treatment to obtain an exchanged liquor, the composition of the exchanged liquor (in terms of the ratio to NaOH) was NaCl/NaOH 1.05, As/NaOH 0.0006, Si/NaOH 0.009, and P/NaOH 0.005, indicating that after one cycle of the mother liquor, the content of arsenic, silicon, and phosphorus (in terms of the ratio to NaOH) was substantially unchanged, and that not only arsenic and phosphorus were not increased, but also decreased, indicating that arsenic, silicon, phosphorus, solidified, and phosphorus in the raw materials, entered the slag.

Example 4 wolframite concentrate containing WO₃65.3%, As 0.1%, Ca 1%, Si 4.2%, 500g, Ca 13.5%, WO₃65.1% of scheelite concentrate to total calcium content of 5.7%, WO₃A65.23% mixed ore was decomposed at 160 ℃ with an alkali amount of 2.3 times the theoretical amount (wherein 1.3 times the circulating alkali mother liquor of example 1 and 1.0 times the added fresh alkali), APT was prepared from the decomposed mother liquor by ion exchange, and the post-exchange liquor components were As/NaOH 0.0007, Si/NaOH 0.008 and NaCl/NaOH 1.12, so that the relative contents of As/NaOH and Si/NaOH were not increased and only NaCl was increased, but referring to examples 1 and 2, it was found that the NaCl/NaOH relative content did not significantly affect the effect of concentration crystallization within the range of 1/1 to 1.4/1.

Example 5 Black tungsten concentrate 500g, example 4, lime Ca (OH) was added₂50g of the thus-obtained post-crosslinking solution containing 6.05% Ca was subjected to alkali decomposition and ion exchange As described in example 4 to obtain a post-crosslinking solution containing 0.00065% As/NaOH, 0.007% Si/NaOH and 1.12% NaCl/NaOH, and the components of the post-crosslinking solution and the components of the added mother liquor were substantially balanced, thereby maintaining the stability of the whole system.

Example 6 hard-dressing wolframite and scheelite mixed middling ore containing WO₃15.2％，Ca 17.4％，As 1.35％，SiO₂35.4%, when the amount of base used was 4.5 times the theoretical amount (2.8 times the circulating base mother liquor as described in example 1, 1.7 times the amount of additional fresh base),the alkali decomposition is carried out at 160 ℃, the components of the post-crosslinking liquid obtained by the ion exchange of the alkali mother liquor are 0.0005 of As/NaOH, 0.008 of Si/NaOH and 0.51/1 of NaCl/NaOH, and the relative content of impurities in the post-crosslinking liquid does not exceed the content of the circulating alkali mother liquor.

Claims

1. A process for preparing ammonium paratungstate from tungsten ore by alkali decomposition-ion exchange method includes adding NaOH to tungsten raw material for alkali decomposition to make the tungsten be Na₂WO₄The form enters into coarse Na₂WO₄Solution, crude Na₂WO₄Ion exchange of the solution to obtain pure (NH)₄)₂WO₄Solution and post-hybridization solution, pure (NH)₄)₂WO₄The solution is sent to prepare ammonium paratungstate, and is characterized in that: adding NaOH, NaCl and WO₄ ^2-And AsO₄ ^3-、PO₄ ^3-、SiO₃ ^2-Concentrating the mixed solution until the concentration of NaOH is 400-₃ ^4-、PO₄ ^3-、SiO₃ ^2-The alkali mother liquor is returned to alkali decomposition.

2. The method of claim 1, wherein: the tungsten mineral raw material to be processed is white tungsten concentrate containing more than or equal to 5 percent of Ca, mixed concentrate containing more than or equal to 5 percent of black tungsten and white tungsten, and refractory tungsten middling with grade more than or equal to 15 percent.

3. The method of claim 1, wherein: when the content of calcium in the tungsten raw material is less than 5 percent, Ca (OH) is added₂Or white tungsten concentrate to make Ca more than or equal to 5 percent.