Access policy guides industry development The National Development and Reform Commission released in October last year the “conditions for access to the calcium carbide industry (revised in 2007)†to require domestic calcium carbide enterprises to develop in a large-scale and group-oriented manner and to completely eliminate the blind investment and construction of low-level calcium carbide projects. The revised access conditions clearly stipulate that the total capacity of the new calcium carbide plant should not be less than 200,000 tons/year, the single furnace capacity should not be less than 50,000 tons/year, and the requirements for the production process should also be more stringent.
At the same time that the "Entry Requirements" was announced, the National Development and Reform Commission also announced the list of the first companies in the calcium carbide industry to eliminate backward production capacity. This move means that China is building a production capacity withdrawal mechanism that is in line with the actual conditions of the industry in eliminating backward production capacity, which is of great significance for the healthy and orderly development of the calcium carbide industry in China.
Differential pricing adjustment of industrial structure China's differential tariff policy has played a positive role in curbing the blind development of high-energy-consuming and high-pollution industries, promoting industrial restructuring, optimizing technological upgrading, and saving energy and reducing emissions. However, in the past three years, the progress of implementation of differential tariffs has been unbalanced. There are also problems such as delays in implementation, lack of in-depth knowledge of high-energy-consuming enterprises, and not all cancellations of electricity price concessions for some high-energy-consuming enterprises.
Since October 20 last year, the preferential electricity prices for the calcium carbide industry have been abolished nationwide, with far-reaching implications for the future development of China's calcium carbide industry. The cost of electricity accounts for nearly 70% of calcium carbide production costs. A small group of small calcium carbide companies with small scale, poor technology, and high pollutant emissions will find it difficult to establish a foothold in the fierce market competition due to rising electricity prices. In the future, China's calcium carbide industry will gradually get rid of the difficulties of low-level, small-scale repeated development and embark on a high-level, large-scale scientific development.
Grading Charges Regulates Calcium Carbide Logistics Calcium carbide products are dangerous chemicals in China. In the course of their production, storage, and transportation, if they are not standardized, they can easily cause serious accidents. In October 2005, the Ministry of Communications issued the "Circular on Printing and Distributing Toll Routes on Guidelines for Toll-by-weight Measures" to regulate and guide the work on the toll-by-weight basis.
With weight-based tolling work being carried out nationwide, how to promote logistics in the new situation has become an issue that cannot be avoided by calcium carbide companies. Today, the main calcium-producing areas in Inner Mongolia, Shanxi, Shaanxi, and Ningxia, etc., have all begun to implement a toll-by-weight standard on highways in China. Under the new transportation conditions, calcium carbide manufacturers need to adjust the product transportation strategy in a timely manner.
Fuel Shortage Compresses Corporate Profits In the fourth quarter of last year, Ningxia, Shanxi, Shaanxi, Inner Mongolia, and other regions all experienced varying degrees of fuel shortages, which led to a significant increase in the cost of calcium carbide products; at the same time, the price of calcium carbide as a raw material for calcium carbide was also due to transportation. The problem was raised dramatically. For a time, the profits of calcium carbide manufacturers have rapidly shrunk under the dual pressure of production costs and transportation costs.
In mid-December of last year, with the joint efforts of the state and two major state-owned oil companies, the domestic refined oil market returned to normal. However, at this time, calcium carbide products have gradually entered the off-season period of consumption, and manufacturers have to lower the transaction price of products under the mild conditions of downstream demand. The profits of enterprises are further compressed.
Excessive production capacity affects the industry trend. Calcium carbide belongs to basic industrial products and its added value is relatively low. Since 2003, the development of China's PVC industry began to increase. The calcium carbide industry experienced a period of expansion from 2003 to 2004 and a period of shock from 2005 to 2006. The overcapacity situation has been curbed to some extent. However, relying too heavily on the PVC market has made the development of the calcium carbide industry a lot of restrictions, and the issue of overcapacity is still severe.
At the same time, more and more calcium carbide PVC companies began to plan to build their own calcium carbide production equipment. Although the development of domestic calcium carbide process PVC will be accelerated in the future, the market reserved for calcium carbide companies will be relatively reduced, which is undoubtedly a challenge to the development of the industry.
Looking ahead, the market conditions faced by the calcium carbide industry will become more severe, but high-level, large-scale is undoubtedly the future direction of development. At present, although China's calcium carbide industry has achieved certain achievements, the exploration of the development path of the calcium carbide industry with Chinese characteristics still needs to continue.
Tungsten carbide roller has characteristics of good wear resistance, high temperature red hardness, thermal fatigue resistance and thermal conductivity and high strength , have been widely used in high-speed wire rod, bar, rebar, seamless steel tubes, etc. Domestic production of tungsten carbide roller materials mostly WC- Co, WC- Co- Ni- Cr two series, and the content of Co, Co- Ni - Cr is in the range of 6wt% ~ 30wt%. From the use of perspective, tungsten carbide rollers has good mechanical properties, its flexural strength up to 2200 MPa or more, shock toughness up (4 ~ 6) × 10^6 J/ m^2, Rockwell hardness (HRA) is up to 78 to 90, widely in the high-speed wire rod rolling process, which is much higher than single-slot chilled cast steel or high speed steel rolls.Tungsten carbide is made of Tungsten Carbide Powder and binder phase (such as drilling, nickel, etc.), and then pressing and sintering, regardless of the conditions under cold rolled or hot rolled has excellent wear resistance, tungsten carbide rollers has been widely used in pre-finishing mill and finishing of high-speed wire rod currently. On the performance of tungsten carbide roller in hot-rolling wire rod , the material must meet the following requirements:
1. Sufficient anti-fracture strength;
2. Good abrasion resistance;
3. The smooth surface finish;
4. Excellent corrosion resistance, thermal fatigue, thermal cracking performance.
Tungsten carbide roller rings can working in bad conditions , small profile rolling (especially rebar rolling) process conditions is harsher than the high-speed wire rod, and therefore corresponds to the profile rolling ,tungsten carbide rollers recommend using high binder phase carbide.
Tungsten carbide roller material design
Pre-finishing all vehicles roller should ensure its high toughness, strength, rigidity and thermal conductivity, followed before considering its wear resistance. When designing each vehicles roller, pre-finishing materials should choose carbide grades of Co, Co- Ni- Cr binder content is high (greater than or equal to 25wt%) , requiring an average WC grain size of coarse (5μm ~ 6μm), to obtain a higher shock toughness, proper strength and hardness. For the finishing of the roller movements, particularly the last two rollers of the finish rolling, which suffered load is small, and high relative velocity of the material to be pressed (80 m / min ~ 120 m / min). In this case, the wear resistance of the roller to be the most important requirements, and must ensure the strength , timpact toughness and hardness of a reasonable match, so the binder of Co / Ni content ratio and the average grain WC control of particle size and other factors must have greater control in front of different pre-finishing rolling roll.
Tungsten carbide roller category
According to the structure of tungsten carbide rollers, it can be divided into solid tungsten carbide roller and composite tungsten carbide roller. Solid tungsten carbide rollers have been widely used in pre-finishing and finishing stands high speed wire rod mill (including fixed reducing the rack, pinch roller rack). Composite tungsten carbide roller is made of cemented carbide and other materials, and it can be divided into tungsten carbide composite roll rings and solid tungsten carbide Composite Roller. Tungsten carbide composite roll rings mounted on the roller shaft; solid tungsten carbide composite roller will be directly cast in the roll axis to form a whole, a large load is applied to the rolling mill.
Tungsten carbide roller production process control
Tungsten carbide rollers produced by powder metallurgy method, the key to its process control is the chemical composition of the material and the mixture was prepared, pressed molding, sintering and deep processing and other preparation process parameters.
1. Preparation of starting material (WC focus quality): As the WC raw material and quality control of the use of different levels of quality may fluctuate, resulting in adverse effects on microstructure.
2. Preparation of the mixture: Mixture preparation is the key to the production process of the roller, the roller of failure modes - trachoma, mainly generated by this procedure.
3. Pressing: roller pressing is an important process of the roller mill.
4. Sintering: roller sintering is to determine the final quality of the roller production processes, use of advanced low-pressure sintering technology, HIP sintering technology can greatly improve the performance of roller.
5. Deep processing: deep processing rollers have a greater impact on the quality and accuracy of the roller surface.
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