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Russian Membrane filter press application in titanium dioxide production
In the production of titanium dioxide sulfate, the primary and secondary washing equipment are mainly vacuum leaf filters. In recent years, with the commissioning of multiple sets of titanium dioxide devices imported from China, membrane filter press technology has begun to replace traditional vacuum leaf filters for water washing processes. This article will introduce the application of membrane filter press in the production of titanium dioxide.
Introduction of the titanium dioxide industry
The current industrial production needs to pay attention to the organic integration of economic and environmental benefits. The titanium dioxide production process has serious environmental pollution, and more waste gas, waste acid, wastewater, and waste residue will be generated during the process.
The scientific name of titanium dioxide is titanium dioxide. Its brightness, whiteness, and opacity are very strong. It is a white inorganic pigment with excellent performance. The main indicators of titanium dioxide are dispersibility, particle size, oil absorption, and whiteness. Generally, it rarely reacts with other chemical elements at room temperature and is an inert substance that is not active.
Application of Traditional Vacuum Leaf Filter in Titanium Dioxide Production
The vacuum is mainly used as the driving force in the titanium dioxide production device, so the vacuum leaf filter is used as the first and second washing equipment.
When washing with metatitanic acid (hydrated titanium dioxide), the leaves in the vacuum leaf filter are first hoisted into the slurry tank by a crane. After the vacuum is turned on, under the action of negative pressure, the filtrate in the slurry passes through the filter cloth and is pumped to the automatic pouring tank through the liquid collection pipe in the leaves, while the metatitanic acid particles are trapped on the filter cloth to form a filter cake. When sucking the slices, the slurry should be continuously added to keep the leaves submerged in the slurry. When the filter cake reaches a certain thickness, the leaves should be lifted while maintaining a vacuum, drained a little, and put into the washing pool. Continuously add clean water, keep the leaves fully immersed, and wash them continuously until they are qualified.
Compared with other filtering equipment, the vacuum leaf filter system has the advantages of simple structure, low cost, large production capacity, etc., and has the functions of filtering and washing, so it has been widely used in the titanium dioxide industry at home and abroad. However, the main disadvantages of the vacuum leaf filter are large water consumption, high labor intensity, intermittent production, difficulty in realizing self-control operation, the equipment occupying a large area, and high one-time investment costs.
In order to improve the environmental protection level of the water washing process, a membrane filter press with higher technical content should be introduced to meet the needs of the treatment work.
Application of Membrane Filter Press in Titanium Dioxide Production
The composition of the membrane filter press includes a membrane plate and a chamber filter plate. During the working process, the slurry will be subjected to the action of the feed pump, and the slurry will be input into the filter chamber. The filter cloth in the filter chamber will filter out the solids in the slurry and then continue to pass air into the membrane chamber to squeeze the solids in the filter chamber to achieve the purpose of controlling the moisture content.
This equipment can change the thrust and direction during the filtration and washing process, meet the requirements of increasing the external force, improve the solid-liquid separation rate in the filtration, and ensure the washing rate. It can reduce the water consumption in the washing process. It can also control power consumption through flexible adjustment so that the water washing has higher efficiency. Moreover, the membrane filter press is also easier to maintain and has high stability during the working process. The hydrated titanium dioxide layer will not be directly exposed on the filter cloth’s surface; it can also avoid pressure loss due to accidents and ensure production reliability.
Using a membrane filter press can reduce the utilization of water resources and the discharge of wastewater, reducing water consumption and the burden of wastewater treatment, which has extremely high environmental benefits. In addition, the diaphragm filter press saves electricity, so it will also have very high economic benefits in the production process, which can bring extremely high comprehensive benefits to the enterprise.
Precautions for membrane filter press used in titanium dioxide washing process
The effect of hydrolyzed material on the membrane filter press washed once
After the hydrolysis of metatitanic acid, the particle size and particle size distribution of hydrated titanium dioxide are the key factors affecting the progress and quality of water washing. They are also one of the important reasons for the success of a membrane filter press in one water washing. In general, the optimum particle size and particle size distribution most suitable for the water-washing process can be achieved by stopping steam heating and stirring at an appropriate time during hydrolysis.
The effect of feeding on the water-washed membrane filter press
The metatitanic acid slurry enters the membrane chamber of the membrane filter press through the pump, and the material forms a filter cake of a certain thickness in the chamber. If the filter cake is too thin, it is easy to cause a short circuit when washing with water; if the filter cake is too thick, it will make washing difficult, and the washing time will be prolonged. In general, a feed pump with a large flow rate and low head should be selected.
Effect of washing temperature and acidity on water washing membrane filter press
Since metatitanic acid water washing is mainly to wash away free acid and iron-based metal sulfates, temperature and acidity directly affect the solubility of iron salts and other metal ion sulfates in water and the pH when they are hydrolyzed to form hydroxide precipitates, so controlling the temperature and acidity of the membrane filter press washing water is one of the main measures to speed up the washing speed and improve the washing quality. It is more appropriate to control the water temperature at 50-60 °C and the pH at 1-2.
Conclusion
Through the above analysis, it is completely feasible to use a membrane filter press for primary and secondary washing instead of a traditional vacuum leaf filter, and it can be gradually popularized and applied in China’s titanium dioxide industry.
