Magnesium oxide desulfurizer: magnesium oxide content 85% - 90%; magnesium oxide activity 62-67%; calcium oxide ≤ 2%; silicon oxide ≤ 5% / 4.5%; burning loss ≤ 6% / 7%; fineness 200 mesh pass rate 90%;

Parameters of light burned powder

MgO %	SiO2 %	CaO %	Fe2O3 %	Al2O3 %	Loi %
80.40	8.02	2.80	0.74	0.16	7.88
85.78	4.85	2.34	0.58	0.12	6.33
90.57	2.77	2.80	0.54	0.17	3.15
92.41	1.90	1.79	0.44	0.12	3.34
93.19	1.88	2.29	0.56	0.19	1.89
94.59	1.27	1.58	0.52	0.17	1.89
95.41	1.29	1.40	0.34	0.07	1.49
96.32	1.24	1.27	0.36	0.10	0.71

Note: the size and parameters can be customized according to the customer's requirements

 

The role of MgO in flue gas desulfurization 

 

Magnesium oxide for desulfurization is mainly used for flue gas desulfurization of power plant boilers and heating boilers.

 

In some factories, such as power plants and heating boiler companies, the waste gas with sulfur dioxide produced by burning coal or other reasons must be desulfurized before discharge to meet the emission standards of environmental protection. At present, there are more than 20 kinds of mature flue gas desulfurization technologies applied in the desulfurization market, and all kinds of different desulfurization methods have their unique advantages. Therefore, when selecting desulfurization technology, it should be considered in combination with the local actual situation. Among them, magnesium oxide wet flue gas desulfurization technology is an economic and practical desulfurization method with good market prospects.

 

In the same case, other desulfurization laws such as calcium desulfurization process have low desulfurization efficiency and high cost.

 

1、 Reaction mechanism of magnesium oxide desulfurization

 

The desulfurization mechanism of magnesium oxide is similar to that of calcium oxide. It is the reaction of basic oxide and water to form hydroxide, then neutralization reaction with sulphurous acid solution formed by dissolving sulfur dioxide in water. Magnesium sulfite and magnesium sulfate produced by reaction of magnesium oxide are recycled after SO2 recovery or forced oxidation to form magnesium sulfate heptahydrate 。

 

The main chemical reactions in the desulfurization process are

 

MgO＋H2O=Mg(OH)2

 

Mg(OH)2＋SO2=MgSO3＋H2O

 

MgSO3＋H2O+SO2=Mg(HSO3)2

 

MgSO3＋1/2O2=MgSO4

 

The main reactions in the regeneration stage of MgO are

 

MgSO3→MgO＋SO2

 

MgSO4→MgO＋SO3

 

Mg(HSO3)2→MgO＋H2O＋2SO2

 

SO2＋1/2O2→SO3

 

SO3＋H2O→H2SO4

 

When the byproduct is forced to oxidize to MgSO4 · 7H2O for sale

 

MgSO3＋1/2O2→MgSO4

 

MgSO4＋7H2O→MgSO4·7H2O

 

 

2、 Advantages and characteristics of MgO desulfurization process

 

1. Mature technology. Magnesium oxide desulfurization technology is a kind of desulfurization technology with maturity next to calcium method. Magnesium oxide desulfurization technology has a lot of application achievements all over the world, among which more than 100 projects have been applied in Japan, 95% of power stations in Taiwan use magnesium oxide method, in addition, it has been applied in the United States, Germany and other places, and at present, it has been applied in some parts of China.

 

2. The source of raw materials is sufficient. The reserves of MgO in our country are very considerable. At present, the proven reserves of MgO are about 16 billion tons, accounting for about 80% of the world. Its resources are mainly distributed in Liaoning, Shandong, Sichuan, Hebei and other provinces, of which Liaoning accounts for 84.7% of the total amount, followed by Laizhou, Shandong, accounting for 10% of the total amount, and the others are mainly in Xingtai River, Hebei, Yandai, Hanyuan, Ganluo, Sichuan, Subei, biegai and other places. Therefore, magnesium oxide can be used as desulfurizer in power plant.

 

3. High desulfurization efficiency. Magnesium oxide is much more active than calcium based desulfurizer in chemical reaction, and the molecular weight of magnesium oxide is smaller than that of calcium carbonate and calcium oxide. Therefore, the desulfurization efficiency of MgO is higher than that of calcium method under the same conditions. In general, the desulfurization efficiency of MgO is over 95-98%, while that of limestone / gypsum is only about 90-95%.

 

4. Less investment cost. Due to the unique advantages of MgO as desulfurization itself, the structure design of the absorption tower, the size of circulating slurry, the overall scale of the system and the power of the equipment can be relatively small, so that the investment cost of the whole desulfurization system can be reduced by more than 20%.

 

5. Low operating cost. The main factors that determine the operation cost of desulfurization system are the consumption cost of desulfurizer and water, electricity and steam. The price of magnesium oxide is higher than that of calcium oxide, but the consumption of removing the same SO2 and magnesium oxide is 40% of that of calcium carbonate; in terms of power consumption such as water, electricity and steam, the liquid gas ratio is a very important factor, which is directly related to the desulfurization efficiency and operation cost of the whole system. For limestone gypsum system, the liquid gas ratio is generally more than 15L / m3, while the MgO is less than 5L / m3, so the MgO desulfurization process can save a lot of costs. At the same time, the sale of byproducts of MgO process can offset a large part of the cost.

 

6. Safe and effective operation. The major advantage of magnesium desulfurization over calcium desulfurization is that the system will not have the problem of equipment scaling and blocking, which can ensure the safe and effective operation of the whole desulfurization system. At the same time, the pH value of magnesium desulfurization is controlled between 6.0 and 6.5. Under this condition, the problem of equipment corrosion has also been solved to a certain extent. In general, the safety performance of magnesium desulfurization in practical engineering has a very strong guarantee.

 

7. The comprehensive benefit is high. Because the reaction products of magnesium desulfurization are magnesium sulfite and magnesium sulfate, the comprehensive utilization value is very high. On the one hand, we can carry out forced oxidation to generate magnesium sulfate completely, and then concentrate and purify to generate magnesium sulfate heptahydrate for sale, on the other hand, we can directly calcine to generate sulfur dioxide gas with high purity to produce sulfuric acid.

 

8. The by-products have a bright future. We know that sulfuric acid is called the "mother of chemical industry", and sulfur dioxide is the raw material for sulfuric acid production. China is a country with a relative lack of sulfur resources. The annual import of sulfur exceeds 5 million tons, equivalent to 7.5 million tons of sulfur dioxide. In addition, magnesium sulfate is widely used in many aspects, such as food, chemical industry, medicine, agriculture and so on. Magnesium desulfurization makes full use of existing resources and promotes the development of circular economy.

 

9. No secondary pollution. In the common wet desulfurization process, there is inevitably the problem of secondary pollution. For magnesium oxide desulfurization technology, the follow-up treatment is more perfect, SO2 is regenerated, and the problem of secondary pollution is solved.

 

 

Through the above analysis, magnesium oxide desulfurization is feasible in theory and fully verified in practical application, which is more suitable for the transformation of new and old boilers. It has a good market prospect in some areas, especially in areas rich in magnesium oxide. Because of the recycling of desulfurizer and the economic benefits of byproducts, and the disadvantages of large-scale wet process are avoided, magnesium oxide desulfurization technology will gradually be more widely used.