METHOD FOR INHIBITING MANGANOUS DITHIONATE BYPRODUCT OBTAINED BY DESULFURIZATION OF PYROLUSITE PULP
TECHNICAL FIELD The present disclosure relates to a method for inhibiting manganous dithionate byproduct obtained by desulfurization of pyrolusite pulp, belonging to the fields of chemistry and metallurgy.
BACKGROUND Sulfur dioxide is an atmospheric pollutant which has the most influence and widest harm to human's environment. In China, a large amount of SO 2 is emitted from coal combustion every year, which causes serious environmental pollution. At present, a variety of dry and wet flue gas desulfurization technologies have been researched and applied at home and abroad, which plays a great role in reducing SO 2 emission. However, the existing desulfurization methods have the problems that initial investment is large, operation cost is high, desulfurization byproduct is low in price, waste residue is little in application value and easily causes secondary pollution, and economic benefits are not obvious. The liquid catalytic oxidation flue gas desulfurization technology can overcome the shortcomings of the traditional desulfurization methods, and has a great application prospect. China is rich in pyrolusite resources, but most of them are low in grade (Mn content is 20%~30%). Desulfurization of flue gas is conducted by utilizing reaction characteristics of pyrolusite and SO2 while realizing comprehensive utilization of lean ores. The absorption of S02 by using pyrolusite pulp can not only control atmospheric pollution, but also by-produce manganese sulfate solution having an industrial value, and thus is a good method for desulfurization and resource utilization. However, in the process of flue gas desulfurization in pyrolusite pulp, the generation of MnS20 is accompanied, which affects the purity of MnSO4 solution and has a negative effect on subsequent manganese electrolysis. Therefore, it is of great economic value to improve the technology of flue gas desulfurization in pyrolusite pulp to obtain pure MnSO4 solution. W02004033738Al discloses a method for inhibiting the generation of desulfurization byproduct MnS20O of pyrolusite by controlling the potential, acidity, reaction temperature and reaction time of leaching solution. However, this method has not been industrialized due to the limitation of leaching temperature and pH, the ratio of iron ions to ferrous ions, the introduction time of SO 2 and other conditions; CN101619388A discloses a method for inhibiting the generation of manganous dithionate in the process of leaching pyrolusite with sulfur dioxide gas, which mainly uses a potential difference between added activated carbon and original iron substances in pyrolusite to form innumerable micro primary batteries in the solution, thereby inhibiting the generation of manganous dithionate. Although this method is low in cost and simple in operation, it will no longer be effective to some pyrolusite pulp containing no iron substances or little iron substances; CN 104645815A discloses a circular separation method of manganous dithionate in desulfurization solution, but this method is cumbersome in operation and low in cost.
SUMMARY When desulfurization is conducted with pyrolusite pulp and manganese sulfate solution is prepared, a manganous dithionate byproduct is generated. The object of the present disclosure is to provide a method for inhibiting a manganous dithionate byproduct obtained by desulfurization of pyrolusite pulp, specifically comprising the steps: smashing pyrolusite powder, evenly mixing pyrolusite with water in a mass ratio of water to pyrolusite being (2-10):1, introducing a gas containing S02, adding ammonium persulfate into pyrolusite pulp in a proportion that 50-100 g of ammonium persulfate is added in each 1 m3 of pyrolusite pulp after introduction of the gas is completed, sufficiently mixing (1030 min), subsequently reacting ammonium persulfate with manganous dithionate to generate ammonium permanganate and ammonium sulfate, heating to remove ammonium permanganate, filtering to remove manganese dioxide generated from ammonium permanganate, thereby obtaining a high-quality electrolytic manganese raw material manganese sulfate solution. Preferably, the granularity of the pyrolusite is not less than 150 meshes. Preferably, the temperature of pyrolusite pulp is controlled at 110°C-120°C in the process of heating. The heating manner of the present disclosure is a conventional manner, which conducts heating by heating pyrolusite with high-temperature flue gas from a smelting plant and a power station, steam heating, fire coal, fuel gas heating, electric heating and other manners. The present disclosure has the beneficial effects: (1) Ammonium persulfate is used as an oxidant to oxidize manganous dithionate into ammonium permanganate and ammonium sulfate. Ammonium permanganate is decomposed at high temperature and produces manganese dioxide. Then, a high-purity manganese sulfate solution is obtained through separation. The method of the present disclosure has high manganous dithionate removal rate, which is close to 100%; while removing manganous dithionate, the produced ammonium sulfate can inhibit the precipitation of hydrogen during manganese electrolysis and improve the precipitation amount of manganese. (2) The method of the present disclosure is simple and continuous in operation, easy to realize industrialization, low in cost, and high in product purity. If the pyrolusite contains iron substances, the oxidation of ammonium persulfate will be strengthened, which is more conducive to the removal of manganous dithionate.
DETAILED DESCRIPTION The present disclosure will be further described in detail in combination with examples. However, the protective scope of the present disclosure is not limited to the described contents. Example 1 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 2:1. The industrial waste gas containing SO2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 50 g of ammonium persulfate was added in each 1 m 3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110°C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.2%, and the purity of MnSO 4 solution was 99.5%. Example 2 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 5:1. The industrial waste gas containing SO2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 50 g of ammonium persulfate was added in each 1 m 3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110°C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.8%, and the purity of MnSO4 solution was 99.6%. Example 3 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 10:1. The industrial waste gas containing SO 2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 50 g of ammonium persulfate was added in each 1 m 3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110 °C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.6%, and the purity of MnSO4 solution was 99.7%. Example 4 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 2:1. The industrial waste gas containing SO2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 80 g of ammonium persulfate is added in each 1 m 3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110°C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.8%, and the purity of MnSO4 solution was 99.4%. Example 5 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 2:1. The industrial waste gas containing SO 2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 100 g of ammonium persulfate is added in each 1 m 3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110°C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.9%, and the purity of MnSO4 solution was 99%. Example 6 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 5:1. The industrial waste gas containing SO2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 80 g of ammonium persulfate is added in each 1 m 3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110°C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.6%, and the purity of MnSO4 solution was 99.5%. Example 7 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 5:1. The industrial waste gas containing SO 2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 100 g of ammonium persulfate is added in each 1I m3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110°C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.9%, and the purity of MnSO4 solution was 98.6%. Example 8 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 10:1. The industrial waste gas containing S02 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 80 g of ammonium persulfate is added in each 1I m3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 115°C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.9%, and the purity of MnSO4 solution was 99.6%. Example 9 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 10:1. The industrial waste gas containing SO 2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 100 g of ammonium persulfate is added in each 1 m 3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110 °C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.9%, and the purity of MnSO4 solution was 99.2%. Example 10
The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 10:1. The industrial waste gas containing SO 2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 100 g of ammonium persulfate is added in each 1 m3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 115°C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.9%, and the purity of MnSO 4 solution was 98.9%. Example 11 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 10:1. The industrial waste gas containing SO 2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 100 g of ammonium persulfate is added in each 1 m3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 120 °C, high-temperature reaction was conducted for 10 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.8%, and the purity of MnSO 4 solution was 99.1%. Example 12 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 10:1. The industrial waste gas containing SO 2 was introduced. After stirring reaction, ammonium persulfate was added in a proportion that 100 g of ammonium persulfate is added in each 1 m3 of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110°C, high-temperature reaction was conducted for 20 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.7%, and the purity of MnSO4 solution was 99%. Example 13 The pyrolusite powder was smashed to a particle size of no less than 150 meshes. Water and manganese ore pulp were prepared into pyrolusite pulp in a mass ratio of 10:1. The industrial waste gas containing SO 2 was introduced. After stirring reaction, ammonium 3 persulfate was added in a proportion that 100 g of ammonium persulfate is added in each 1 m of pyrolusite pulp. The above mixture was heated via afterheat of waste gas so that the temperature was maintained to be 110 °C, high-temperature reaction was conducted for 30 min, manganese dioxide was separated out, and naturally cooling was conducted, so as to finally obtain manganese sulfate solution. In this example, the removal rate of manganous dithionate was 99.8%, and the purity of MnSO4 solution was 99.6%.