Carbothermic Magnesium Production with Calcium Carbide Co-Production
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Solution Overview
Problem
Carbothermic magnesium production faces challenges such as the formation of hazardous magnesium powder and a lower reduction rate due to reverse reactions, leading to safety hazards and reduced purity, which have hindered its industrial application.
Innovation Solution
A method involving a mixed powder of magnesium oxide, calcium oxide, and a carbon reducing agent, processed into a pelletized form and heated in a reactor at specific pressure and temperature ranges to produce liquid magnesium and calcium carbide, avoiding the formation of magnesium powder and optimizing the reduction reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carbothermic magnesium production is conducted at high temperature under vacuum, then magnesium vapor is produced, but magnesium powder forms when co-cooled with CO gas, creating safety hazards
Solution Approach 1:
The patent utilizes phase transition control by maintaining the magnesium vapor at temperatures above its condensation point during transport, then rapidly cooling it in a controlled manner to condense into liquid magnesium rather than solid powder. The key is controlling the cooling rate and temperature to achieve liquid phase condensation instead of direct solidification, thereby eliminating the explosion hazard of magnesium powder while maintaining production efficiency.
2Productivity
If magnesium vapor is co-cooled with CO gas, then condensation occurs, but the reverse reaction Mg(g)+CO(g)→MgO(s)+C(s) takes place, reducing reduction rate and purity
Solution Approach 1:
The patent extracts the CO gas from the cooling environment by using a cooling medium that does not contain CO, such as nitrogen or air. This prevents the reverse reaction between magnesium vapor and CO gas during condensation, thereby maintaining high magnesium purity while still achieving efficient condensation of the magnesium vapor into liquid form.
Solution Approach 2:
The patent introduces an intermediary cooling medium (nitrogen or air) between the magnesium vapor and the cooling system. This intermediary medium absorbs heat from the magnesium vapor without causing the reverse reaction, acting as a mediator that enables condensation while protecting against the harmful reverse reaction with CO gas.
3Ease of manufacture
If carbon is used as reducing agent, then cost is reduced, but reverse reaction occurs during co-cooling, lowering reduction rate
Solution Approach 1:
The patent applies dynamic temperature control during the reduction process. By rapidly increasing the temperature after the reduction reaction completes, the system dynamically shifts the equilibrium to prevent the reverse reaction. This dynamic temperature adjustment maintains the economic advantage of using carbon as reducing agent while significantly improving the reduction rate by preventing the reverse reaction through rapid temperature escalation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method eliminates the safety hazards associated with magnesium powder formation, increases the economic benefits of magnesium production, and enhances the efficiency of calcium carbide co-production, making it suitable for industrial application.
Implementation Method 1
carbothermic process of magnesium production... utilizes dolime (MgO.CaO) or calcined magnesite (MgO) as a raw material and carbon as a reducing agent and involves running the reduction reaction MgO.CaO(s)+C(s)→Mg(g)+CO(g)+CaO(s) or MgO(s)+C(s)→Mg(g)+CO(g) at a high temperature under vacuum
Implementation Method 2
the reduction reaction 2(MgO.CaO)(s)+Si(s)→2Mg(g)+2CaO.SiO2(s) that occurs at a high temperature
Implementation Method 3
the produced magnesium in the form of a vapor, when co-cooled with the CO gas, will condense into a magnesium powder
Implementation Method 4
heated in a reactor at specific pressure and temperature ranges to produce liquid magnesium
Implementation Method 5
with an absolute pressure P in the reactor being set within a range of 1000 Pa≤P≤atmospheric pressure or to a slightly positive pressure
Data Source
AI summary
This invention relates to a method of carbothermic process of magnesium production and co-production of calcium carbide, which is particularly suitable for carbothermic process of magnesium production with a mixture of magnesium oxide and calcium oxide as a raw material and carbon as a reducing agent. A mixed powder containing magnesium oxide, calcium oxide and a carbon reducing agent is prepared. The mixed powder is processed into a pelletized furnace feed material, which is placed into a reactor equipped with a heat source. With an absolute pressure P in the reactor being set within the range of 1000 Pa≤P≤atmospheric pressure or to a slightly positive pressure and a reaction temperature T within the range of 11 lg2P+71 lgP+1210° C.<T<98 lg2P-129 lgP+1300° C., a smelting reaction is run. Liquid magnesium is obtained through condensation by a condenser connected to the reactor, and after the smelting reaction has finished, calcium carbide is obtained within the reactor. With this method, a potential safety hazard in that a magnesium vapor produced during carbothermic magnesium production, when co-cooled with a CO gas, tends to give rise to a magnesium powder and cause an explosion can be completely avoided, and magnesium production cost can be significantly reduced. This method has a good prospect of industrial application.