Since vanadium in stone coal mainly occurs in clay minerals, it is easily converted into a soluble state by oxidative roasting. In the late 1980s, most of the stone coal vanadium plants in China used the following process.
The traditional process of extracting vanadium from stone coal
The main technical index of the process is (%): the conversion rate of flat kiln roasting is less than 53, the recovery rate of water immersion is 88-93, the recovery rate of hydrolyzed thick V 2 O 5 is 92-96, the recovery rate of refining is 90-93, total smelting The recovery rate is lower than 45.
The low conversion rate of sodium salt roasting is one of the main drawbacks of the conventional process. There are many factors affecting the conversion rate, such as calcination temperature, time, type of additive, ratio of ingredients, calcination atmosphere, particle size of the ingredients, and the like. The table below lists the best roasting conditions and conversion rates for some stone coal vanadium plants. It can be seen that most of the roasting additives use salt, and the use of mirabilite or salt plus Glauber's salt can also achieve better results.
The advantages of the traditional process are: the process is simple, the process conditions are not harsh, the equipment is simple, the investment is small, and the infrastructure is relatively fast. However, in addition to the low recovery rate, a large amount of flue gas containing hydrogen chloride, chlorine gas and sulfur dioxide discharged from the flat kiln roasting and the waste liquid after the crude V 2 O 2 precipitation are serious sources of pollution. The low comprehensive utilization rate of the flat kiln's large-scale resources cannot be ignored.
Table The best roasting conditions for vanadium extraction in some stone mines
Mining area | Additive type and ratio | Roasting time (h) | Calcination temperature (°C) | Calcination conversion rate (%) |
Zhejiang Zhuji Mine | Mine (with charcoal): NaCl = 100: 16 ~ 18 | >3.2 | 830 °C ± 20 (fluidization roasting) | 72.8~78 |
Hunan Yiyang Mine | Mine (decarbonization): NaCl = 100: 10 | 1 | 800 | 71.1~74.1 |
Sichuan Wushan Mine | Mine (decarbonization): NaCl = 100: 14 ~ 18 | 2 | 750-800 | 64~68 |
Sichuan Wuxi Mine | Mine (with carbon + decarbonization): NaCl = 100: 16 ~ 20 | 3 to 4 | 750-850 | 56.89~62.72 |
Hunan Yueyang Xinkaitang Mine | Mine (decarbonization): NaCl = 100: 10 | 1 | 750 or less | 71.7 |
Fangshankou Mine, Gansu | NaCl Na 2 SO 4 , NaCl + Na 2 SO 4 | 800～850 800～850 | 78.0～82 60～70 |
Interior Lights For Car,Dashboard Accessories,Car Dashboard Decoration,Car Interior Decoration Items
Ningbo Longyang Auto Products Co., Ltd. , https://www.longyang-manufacturer.com