Non-polluting vanadium ore dressing test

The vanadium ore existing in the adsorption and dispersion state of a vanadium ore system in Shaanxi is not suitable for enrichment by mechanical beneficiation . Among the similar ores in the region, there are roughly two types of vanadium extraction methods. One is the traditional sodium roasting and vanadium extraction process. The process technology is mature and simple to operate. The investment in construction and production is relatively low, but due to the use of industrial salt. As a sodiuming agent, a large amount of toxic gases such as chlorine and hydrogen chloride are generated during roasting, causing serious damage to the surrounding environment. Second, the acid leaching-extraction vanadium extraction process can reduce environmental pollution, but the production cost and investment in the plant have been invested. Big, causing production companies to be overwhelmed. This study shows that the use of ultra-fine grinding-free additive roasting-assisted leaching vanadium extraction process can achieve better test indicators without causing environmental pollution. In the current situation of ultra-fine grinding technology becoming more and more perfect and the cost is decreasing. The new technology has shown new prospects for the development and utilization of this type of ore.

First, the nature of the ore

Shale ore types of ore mixed with charcoal siliceous rocks, ore containing V ₂ O ₅ 1.60%, mainly metal ore minerals brown iron pyrite, anatase vanadium iron, vanadium, iron and the like. The main non-metallic minerals as quartz, and carbonaceous shale, as well as small amounts of apatite and carbonate minerals. The occurrence of vanadium is complicated. Except for distribution in vanadium iron or vanadium iron anatase, electron probe analysis shows that vanadium is widely dispersed in quartz and limonite, which account for a large proportion of ore. The results of multi-element analysis of raw ore are shown in Table 1.

Table 1 Multi-element analysis results of raw ore  

Second, the vanadium extraction process

(1) Experimental assumptions

The low-valent vanadium in the ore can be oxidized to V ₂ O ₅ by calcination. If it can form a soluble salt with the K and Na elements contained in the ore itself, an additional leaching agent which is beneficial to the dissolution of the salt can be added in the leaching operation. The vanadium in the ore is effectively transformed, and then the vanadium containing V ₂ O _{5 is} obtained by the second stage vanadium precipitation operation.

(2) The influence of main factors on the roasting rate of roasting

1. Influence of grinding fineness on roasting leaching rate:

The effect of grinding fineness on roasting leaching rate is shown in Table 2.

Table 2 Effect of grinding fineness on roasting leaching rate

The test results show that the finer the grinding fineness, the higher the roasting rate.

2. Effect of calcination temperature on conversion rate

The effect of calcination temperature on the conversion rate is shown in Table 3.

Table 3 Effect of calcination temperature on conversion rate   

The test results show that the conversion rate is very low at 750 °C. When the temperature rises to 800 °C, the conversion rate rises sharply to 76.88%, and it tends to be stable after 800 °C.

3. Effect of roasting time on conversion rate

The effect of baking time on the conversion rate is shown in Table 4.

Table 4 Effect of roasting time on conversion rate   

The test results show that the conversion rate increases with the increase of roasting time, but tends to be stable after more than 2 hours.

(III) Comparison of new process and sodium leaching roasting rate

The similarities and differences between the new roasting and leaching operations and the sodium roasting method are shown in Table 5.

Table 5 Similarities and differences between sodiumation process and new process

(4) Other operations

After the ore grinding and roasting, the mixture is heated and stirred for leaching, and the leaching solution is subjected to the second stage vanadium precipitation. The comprehensive closed-circuit test can obtain the total recovery rate of vanadium extraction of 72.26%, and the refined vanadium grade is over 98%.

Third, the results of the discussion

Compared with the sodium roasting method, the new process is similar to the test index. The main difference in the roasting and leaching section is sodiumation roasting and sodium sulphide sodium chloride. The new process uses ultrafine grinding, and the leaching section performs assisted leaching. The main advantage is that it is non-polluting.

The data indicates that the firing mechanism is:

Mechanism of roasting sodiumation:

2NaCl+O ₂ +H ₂ O(g)+V ₂ O ₃ =2NaVO ₃ +HCl↑

4NaCl+3O ₂ +2V ₂ O ₃ =4NaVO ₃ +2Cl ₂ ↑

Among them, hydrogen chloride and chlorine release the polluted environment.

What happens when the new process is calcined is only the oxidation reaction of low-valent vanadium.

V ₂ O ₃ + O ₂ = V ₂ O ₅

2V ₂ O ₄ + O ₂ = 2V ₂ O ₅

Therefore, it does not cause air pollution.

In terms of production cost, the cost of sodium chloride required for sodium roasting can partially or even offset the cost of ultrafine grinding in the new process. With the further development of ultrafine grinding technology, the grinding cost is possible. Further decrease.

Fourth, the conclusion

(1) In this test, the ultra-fine grinding-free additive roasting-assisted leaching vanadium extraction process can achieve more than 75% vanadium roasting conversion rate, and the comprehensive closed-circuit test can obtain 72.26% total vanadium recovery rate. The refined vanadium grade is achieved. More than 98% of the test indicators.

(2) The new process is a non-polluting process, and the production cost is close to that of sodium roasting, and with the continuous development of ultra-fine grinding technology, it is possible to further reduce it.