DE2219251C3 - Process for the production of vanadium pentoxide - Google Patents

Description

V ₂ O, - 13% Fe ₁ O ₄ - 783% TiO ₂ = 13.0% AI ₂ Oj - 4.0% SiO ₂ - 2.8%

jo

15th

Vanadium-containing slags or vanadium-containing ores (e.g. magnetites) are preferably used as raw materials for the production of vanadium pentoxide. For the extraction of vanadium were acid and alkaline working method developed The preferred procedure, especially in the recovery from ores that pyrogenalkalische digestion with alkali salts at 800-1300 ⁰ C disadvantage h € \ this method is the simultaneous Aufsckhiß present in the starting material SiOrVerbindunge · · To water-soluble alkali silicates. During the aqueous extraction of the roasted product, these go into solution together with the soluble alkali vanadates to a considerable extent.

To produce a low-alkali vanadium pentoxide, the vanadium is precipitated from these solutions in the form of ammonium compounds in a neutral to slightly alkaline pH range. The silica in solution falls almost completely with and contaminate the v ~> ammonium vanadate or vanadium pentoxide obtained therefrom by decomposition, whose value is thus greatly reduced For example obtained when pyrogen-alkaline digestion of a Titanmagnetiis having the following analysis:> o

above 900 ⁰ C a sintering, the silica-rich during the extraction with water with a Vanadatlaugen SiOrGehalt of about 2 g / l provides. The ammonium vanadate precipitated therefrom has the following analysis: m>

V = 413%
Na ₂ O - 0.7%
SiO ₂ = 2.8%

This purity does not meet the current requirements for many areas of application. The SiO ₂ and Na ₂ O content are of good V ₂ Ov quality. below 0.5%.

The aim of the invention is to remove the silica from vanadium-containing liquors before the aminonium vanadate precipitation. This is achieved by the fact that in the aqueous extraction of the pyrogenic alkaline sinter dissolved silica converts to insoluble alkali, especially sodium aluminum silicate and this through z. B. Separation by filtration.

Surprisingly, it was found that practically complete separation of the silica from vanadate liquors via sodium aluminum silicate compounds even at room temperature and in neutral to weakly alkaline pH range can be carried out. All water-soluble reagents are suitable as precipitation reagents Aluminum compounds, especially alkali aluminates, aluminum sulfate, alums and aluminum chloride. For a practically complete SiOr deposition it is necessary to maintain the molar ratio Al: Si of at least 1: I expedient (Fig. 1).

The production of sodium aluminate is by adding aluminum hydroxide or oxide in the form of Bauxite or the pure compounds in the pyrogenic alkaline digestion of the vanadium ore or the Vanadium slag possible.

Application examples

The following examples show the dependence of the silica deposition on the reaction time Reaction temperature, the concentration of the precipitant and the pH of the lye to be decilified emerged.

Example I.
II each of a weakly alkaline sodium vanadium lye with

18 g / l V
1.28g / SiO ₂
pH 9.8

varying amounts of solid sodium aluminate were added and the ^{mixture was stirred at 70 °} C. for 15 minutes. After decanting, the clarified liquor was _{examined for SiO 2} and V. Table I shows the values found.

• aluminate MV 22nd 19th 251 V SiOj 4th V / SiOa Degree of precipitation 3
table 1 Al; g / l g / l module % N / A PH g / l Si

Original eye
Desiccated lye

0.67

1.1

1.54

2.2

3.3

4.4

In Example 2 1 1 of Na vanadate liquor was used with each

17 g / l V 0.44 g / l SiO ₂ pH 93

by means of sulfuric acid to pH 7.5. At room temperature varying amounts of a 10%.

Table 2

9.8 18th 1.28 14th 57 0.3: 1 9.9 18th 0.55 33 77 0.5: 1 9.9 18th 0.29 62 87 0.7: 1 9.9 18th 0.17 105 > 98 1; 1 9.9 18th <0.03 600 > 98 1.5: 1 9.9 18th <0.03 600 > 98
Löüiin? 2: 1 9.9
alkaline ι =; sai 18th
jerreaffiere <0.03
nd Alumi 600
niiimsnlfat

20th

added.

As a result, the pH of the lye to be decilified fell to 6.5. After a reaction time of 15 minutes the precipitate which precipitated out quickly was separated from the supernatant liquor by decanting.

Table 2 shows the silica removal results.

Al2 {SO4) j- Molver- Solution ratio

IO% Al: Si (cm ') pH

g / l

S1O2
g / l

V / S1O2
module

Degree of precipitation

Original eye
Silicified alkalis

50

20th

100

10

4: 1

1.6: 1

8: 1

0.8: 1

0.4: 1 6.8
7.0
6.5
73

17th

16.2

16.7

15.4

17th

17th

0.44

0.03
0.03
0.03
0.04
0.09

600
600
600
400
200

95 95 95 90 80

In Example 3, 1 l of a lye was used with each

20 g / l V 1.7 g / l SiO ₂ pH 10.5

heated to 70 ^° C. and stirred in 3 g of solid sodium aluminate corresponding to the molar ratio Al: Si = 1: 1. The reaction time was varied between 3 and 30 minutes. After the precipitate had been separated off by centrifugation, SiO ₂ and V were determined in the clear liquor.

The results are shown in FIG. It is E.g. it can be seen that the desilification is completed after about minutes.

Table 3

In Example 4, various aluminum salts were tested as precipitants. A lye was used

17.4 g / l V
1.13 g / l SiO ₂
pH 9.9

The amount of precipitant was set to a molar ratio of Al: Si = 1.2: 1. The reaction ^{temperature chosen was 90 °} C. and the reaction time 15 minutes. After the reaction had taken place, the pH was adjusted to 7 _{with concentrated H 2 SO *, the mixture was centrifuged and SiO 2} and V were determined.

The results are compared in table 3:

Addition V
g / l

SiO?
g / l

V / S1O2
module

Degree of old case%

Original eye
Silicified alkalis 17.4

1.13

-15

NaAIO ₂ AIi (SQi) J AICh potassium alum

17.1 0, \ A 430 963 16.7 0.06 28Q 95 16.7 0.06 280 95 16.8 0.06 280 * 5

In example 5, the silica removal was carried out in technical b5. 5 tons of titanium magnetite were used as the starting material Practiced standard. This experiment shows at the same time according to the analysis on page I of the present

one of the ways the desilification according to the description. The ore was made on a grain

Invention to carry out technically. <90μηι ball-milled and after mixing with t0%

finely ground sodium sulphate pelletized. The received Pellets were then roasted at about 1200 ° C.

The solid sintered spheres obtained were leached with water. In Fig.3 curve 1 is the solubility dependency of the silica - expressed as modulus = quotient of V and S1O2 - of the leaching temperature reproduced. It can be seen that the SiO solubility increases as the leaching temperature rises. These alkalis are not suitable for the production of pure ammonium vanadate. The application of the Invention is made in such a way that sodium aluminate powder is poured between the pellets during the leaching process. The incoming water takes the Precipitant particles with. so that when you extract the Sodium Vanadate and Sodium Silicate the latter themselves Immediately reacted with dissolved sodium aluminate to form insoluble N.iirmm; ilnmiumsilil <; ii. After leaching will neutralized, pressure filtered and thereby the solid sodium aluminum silicate severed. The clear liquor is

practically SiOj-free and can be used immediately for the deposition of the Vanadium can be used as ammonium vanadate (Fig. 3. Curve 2).

Table 4 shows the difference in quality of ammonium vanadate with and without desiccation remove.

With the proposed method it is now possible to use ores for vanadium extraction to make, the processing of which was previously uneconomical due to an increased SiOr content.

Table 4

Ammonium vanadate
from silica containing
Lye
from desiccated lye

41.5
42.5

SiOj

2.8
0.2

NaX)

0.7
0.3

1 sheet of drawings

Claims (4)

Patent claims: 1. Process for the production of vanadium pentoxide by pyrogenic alkaline digestion of ores containing silicic acid containing vanadium compounds or slags with alkali salts 800-1300 ° C aqueous extraction of the digested material and subsequent precipitation of the vanadium in the form of ammonium-vanadium compounds, and conversion of the same into the pentoxide, characterized in that the at Digestion of dissolved silica from the vanadium-containing lye before ammonium vanadate precipitation to insoluble alkali, especially sodium aluminum silicate, implemented and this by z. B. Filtration is separated. 2. The method according to claim 1, characterized in that that the precipitation of the silica in the ϊ neutral to weakly alkaline pH range is carried out, 3. Process according to Claims I and 2, characterized in that the precipitation reagents water-soluble aluminum compounds, especially alkali aluminates, aluminum sulfate, or alums Aluminum chloride is used. 4. Process according to claims 1-3, characterized in that the precipitation reagent, e.g. Alkali aluminate, by adding aluminum hydroxide. Aluminum oxide and / or bauxite in the case of pyrogenic alkaline Digestion of the ores or slags containing vanadium compounds are generated directly will.