Titanium dioxide is a kind of white inorganic pigment. It has the characteristics of innocuity, excellent opacity, whiteness and brightness. It is widely used in paints, plastics, paper making, printing inks, chemical fiber, rubber and cosmetics industries. At present, the production process of rutile titanium dioxide is composed of two parts: the production of titanium white powder base material and the post processing. Post processing can overcome some inherent defects in titanium dioxide powder, prevent direct contact between titanium dioxide and light, air and water, and improve glossiness, whiteness and weatherability. At present, the domestic post-processing technology is still relatively backward, how to improve the post-processing technology has always been the key research topic of the titanium dioxide production enterprises.

1.国内钛白粉后处理工艺现状

The status of post-treatment technology of 1. domestic titanium dioxide powder

国内钛白粉后处理工艺流程为：

The post treatment process of titanium dioxide in China is as follows:

1. 1 研磨

1.1 grinding

研磨又称为研磨分散，该工序是将加入分散剂分散后的TiO2浆料进行机械研磨，目的是使团聚在一块的TiO2颗粒分离成单个粒子。

Grinding is also known as grinding and dispersing. The process is mechanical grinding with dispersing agent dispersed TiO2 slurry, so that the agglomeration of TiO2 particles into a single particle can be separated.

1. 2 分级

1.2 classification

此工序的目的是将研磨后浆料中剩余的大颗粒物料分离出来，使粒径集中，粒径分布变窄，满足包膜要求。

The purpose of this process is to separate the large particle material remaining in the grout after grinding, so that the particle size is concentrated and the particle size distribution narrowed, so as to meet the requirements of the coating.

1. 3 包膜

1.3 envelope

包膜就是通过化学反应在粒子表面包覆一层薄膜状的物质，又称为表面处理。包膜质量的好坏直接影响着产品的使用性能。

A coating is a coating of a thin film on the surface of a particle by chemical reaction, also known as surface treatment. The quality of the coating directly affects the performance of the product.

1. 4 洗涤

1.4 washing

洗涤是用水洗的方式将表面处理后的钛白粉上的盐类物质除去，避免影响产品的应用性能。

Washing is to remove the salt material from the titanium white powder treated by water washing, so as to avoid the application performance of the product.

1. 5 干燥

1.5 drying

经洗涤、过滤后，钛白含有大量的水分，需对其进行干燥处理。传统生产工艺中，常用的有带式干燥、喷雾干燥和旋转闪蒸干燥。

After washing and filtering, the titanium dioxide contains a lot of water and needs to be dried. In the traditional production process, it is often used as belt drying, spray drying and rotary flash drying.

1. 6 粉碎

1.6 comminution

收集下来的钛白粉大都是粒子聚集物，需要粉碎后才能使粒度达到标准要求，从而获得尽可能高的不透明度及遮盖性能。

Most of the collected titanium dioxide particles are particle aggregates, which need to be crushed to meet the standard requirements, so as to get the highest opacity and covering performance.

2 后处理工艺的改进

Improvement of 2 post treatment process

2. 1 分级工艺的改进

Improvement of 2.1 classification process

国外普遍选用水力旋流器对研磨后的浆料进行分级，使包膜前物料达到单一粒子状态，满足包膜要求。该设备的分级效率高，准确性好。近几年国内钛白粉厂也开始使用该设备进行分级。

The hydrocyclone is widely used in foreign countries to classify the grinded slurry, so that the materials before the coating can reach the single particle state and meet the requirements of the coating. The classification efficiency of the equipment is high and the accuracy is good. In recent years, the domestic titanium dioxide factory has also started to use this equipment for classification.

2. 2 包膜工艺的改进

Improvement of 2.2 coating process

包膜是钛白粉后处理的关键工序，对于包膜罐的选型适宜采用大型包膜罐，这样利于包膜产品质量的稳定。国外包膜工序与国内最大的不同是其包膜为全自动控制完成，整个包膜的过程采用先进的 DCS 系统进行操作，减少了产品质量不稳定，节省了包膜时间，提高了生产效率。同时国外对于包膜剂的杂质含量控制比国内高很多，这也是国外钛白粉质量优于国内的一个关键因素。

The coating is the key process for the post treatment of titanium dioxide, and the large coating tank is suitable for the selection of the coating tank, which is conducive to the stability of the quality of the coated products. The biggest difference between foreign coating process and domestic is that the coating is completed by automatic control. The whole coating process is operated by advanced DCS system, which reduces product quality instability, saves coating time and improves production efficiency. At the same time, the control of the impurity content of the coating agent abroad is much higher than that in the country, which is also a key factor in the quality of the foreign titanium white powder superior to the domestic.

2. 3 洗涤工艺的改进

Improvement of 2.3 washing process

为了进行有效的洗涤和过滤，国外多采用隔膜压滤机进行洗涤压滤，国内近几年也逐渐开始使用该设备进行洗涤，但存在的问题是国内使用该设备压滤出来的滤饼固含量低，洗涤周期长，不利于后续干燥的开展。国外使用隔膜压滤机设备自动化程度高，洗涤水耗低，过滤操作时间比传统洗涤时间短，采用的滤板耐压性能好，滤饼含水量低，更节能环保。

In order to carry out effective washing and filtering, the use of foreign diaphragm filter press filter for washing, in recent years China has gradually started to use the equipment for washing, but the problem is that the domestic use of the device filter cake out of the solid content is low, the washing cycle is long, is not conducive to the subsequent drying out. The membrane filter press abroad has the advantages of high automation, low washing water consumption and short filtration operation time than traditional washing time. The filter board has good pressure resistance, low water content of filter cake and more energy saving and environmental protection.

2. 4 干燥工艺的改进

Improvement of 2.4 drying process

为了进行有效的洗涤和过滤，国外多采用隔膜压滤机进行洗涤压滤，国内近几年也逐渐开始使用该设备进行洗涤，但存在的问题是国内使用该设备压滤出来的滤饼固含量低，洗涤周期长，不利于后续干燥的开展。国外使用隔膜压滤机设备自动化程度高，洗涤水耗低，过滤操作时间比传统洗涤时间短，采用的滤板耐压性能好，滤饼含水量低，更节能环保。

In order to carry out effective washing and filtering, the use of foreign diaphragm filter press filter for washing, in recent years China has gradually started to use the equipment for washing, but the problem is that the domestic use of the device filter cake out of the solid content is low, the washing cycle is long, is not conducive to the subsequent drying out. The membrane filter press abroad has the advantages of high automation, low washing water consumption and short filtration operation time than traditional washing time. The filter board has good pressure resistance, low water content of filter cake and more energy saving and environmental protection.

2. 5 粉碎工艺的改进

Improvement of 2.5 comminution process

为了进行有效的洗涤和过滤，国外多采用隔膜压滤机进行洗涤压滤，国内近几年也逐渐开始使用该设备进行洗涤，但存在的问题是国内使用该设备压滤出来的滤饼固含量低，洗涤周期长，不利于后续干燥的开展。国外使用隔膜压滤机设备自动化程度高，洗涤水耗低，过滤操作时间比传统洗涤时间短，采用的滤板耐压性能好，滤饼含水量低，更节能环保。

In order to carry out effective washing and filtering, the use of foreign diaphragm filter press filter for washing, in recent years China has gradually started to use the equipment for washing, but the problem is that the domestic use of the device filter cake out of the solid content is low, the washing cycle is long, is not conducive to the subsequent drying out. The membrane filter press abroad has the advantages of high automation, low washing water consumption and short filtration operation time than traditional washing time. The filter board has good pressure resistance, low water content of filter cake and more energy saving and environmental protection.

3 后处理工艺发展方向

Development direction of 3 post treatment process

同国际先进技术相比，国内钛白粉生产还存在诸多不足，从钛白粉目前的研究现状来看，今后应加强以下几方面的研究:1) 深入研究包膜技术的工艺过程，包括对现有包膜剂进行改进;2) 加大对砂磨机、隔膜压滤机及闪蒸干燥机等设备的研发力度，开发出低能耗、高生产效率的大型钛白粉后处理设备;3)开发新的设备材质将是研究的关键。

Compared with the international advanced technology, domestic production of titanium dioxide has many problems, from the current research status of titanium dioxide, we should strengthen the study of the following aspects: 1) the process of in-depth study of coating technology, including the existing coating agent is improved; 2) to increase the research of sand mill, and diaphragm filter press flash dryer and other equipment, develop high production efficiency and low energy consumption, large titanium dioxide postprocessing equipment; 3) the development of new equipment is the key of the study will be.

4 结 语

4 Conclusion

后处理加工是钛白粉生产过程的主要组成部分，在提高钛白粉的使用性能方面发挥了重要的作用。随着全球白色颜料产业迅速发展，人们对高性能钛白粉的需求不断地推动着后处理工艺技术的创新和改进。可以预见的是，随着国产设备性能的不断提升及包膜配方的进一步优化，国产氯化法钛白粉将在更广阔的国际舞台上

Post-processing is the main component of the production process of titanium dioxide, which plays an important role in improving the performance of titanium dioxide. With the rapid development of the white pigment industry in the world, the demand for high performance titanium dioxide has continuously promoted the innovation and improvement of the post-processing technology. It can be predicted that with the further optimization and constantly improve the performance of the domestic equipment and coating formulation, domestic chlorination process titanium dioxide in a broader international arena