Technical transformation case for U-steel in Nigeria

From 2006 to 2010, served as general manager in universal steel company in Lagos sate in Nigeria, responsible for the overall management of EAF, CCM and Rolling mill.  

Factory background

Founded in 1976, universal steel company has developed from a single steel rolling company to the largest steel company in West Africa. After 30 years of development, it has become a steel company with complete processes of EAF steelmaking, continuous casting and rolling mill, and has refractory plants and mechanical processing plants supporting steel mills. Due to its backward production in Africa, the equipment and equipment level of the production line was relatively backward, and the production technology was far behind the same type of iron and steel enterprises in Chinese mainland.

In view of this situation, through technological innovation and management innovation, a number of reforms have been carried out on the raw material management, raw material application, refractory application and process operation technology of the steel plant, which greatly reduced the production cost of the steel plant and created considerable benefits for the company.

Factory management reform and its effect

1.Logistics management of raw and auxiliaty materials

Through the inventory of refractories, graphite electrodes, spare parts and spare parts of the whole factory, we could make them synchronous and orderly, reduced the unnecessary purchasing funds to the maximum extent, and then made the logistics scientific and reasonable.

1.1.Refractory

In the past, the management of refractory was chaotic, and the synchronization of dozens of varieties of refractory in stock was very poor, that is, the actual use time of different types of refractory was very different. Through accurate calculation, the shortage type was added by purchase and supplement, so as to maximize the synchronous consumption and saved a lot of procurement funds for the company.

1.2.Graphite electrode

Through the inventory, the number of electrodes and electrode joints will be checked in the future procurement process to make up for deficiencies, accurately and synchronously matching, so as to make the electrode management. At the same time, the broken electrodes which can be reprocessed are collected in the mechanical processing plant, and the broken electrodes with recycling value are recycled in large quantities, which saves considerable electrode purchasing funds for the company.

In addition, the small segments worthless electrode blocks with no reprocessing on site were crushed intensively and used as carburizing agent in the EAF production process, which not only improved the on-site environmental hygiene, but also achieved the effect of waste recycling.

1.3.Spare parts

After the inventory of spare parts, the corresponding synchronous leak detection and replenishment were also done, which greatly reduced the waste of purchasing funds caused by the excess inventory of a certain type.

2.Technical transformation

2.1 Electric furnace area

① EAF Lining 

At that time, the EAF lining in the factory was the light burned magnesia bricks produced by the company's internal refractory factory. The service life of the lining was basically one week, and the furnace lining had to be replaced every week during the maintenance time. The service life of the refractory was short, the furnace repair times were many, the labor intensity of workers was high, and the cost of refractory was high, which seriously affected the operation time of EAF.

In view of this situation, it was suggested that the company introduced the mature technology of magnesia carbon brick lining from China. This technical transformation greatly improved the lining life, shortened the downturn time, and greatly reduced the refractory consumption for steelmaking.

② Refractory for ladle 

The factory has been using high alumina brick as ladle lining, which had short service life. Because it was easy to infiltrate with steel slag, it was difficult for workers to clean  slag, and labor intensity was high. It was suggested to use domestic mature magnesia carbon brick for masonry, which overcame the defects of high alumina brick and greatly reduced the production cost.

③ Deoxidizing material

The introduction of domestic silicon carbide and blue carbon powder as diffusion deoxidizer, the combination of diffusion deoxidation and precipitation deoxidation could accelerate the reduction efficiency of electric furnace and effectively shortened the smelting time.

④Slagging material

Local calcite is used as slag-making material and calcite is a crystal form of calcium carbonate. Due to the lack of lime resources in the local area, in order to better cooperate with the use of alkaline refractory materials, played its ideal service life and overcame the disadvantages of steel-making without making alkaline before, the implementation of this technology has excellent integration benefit from the perspective of prolonging the lining life and ladle life economic performance.

⑤ Material for tapping trough

In the past, the tapping trough has been rammed quartz sand with water glass . In the production process, the hot repair was frequent, the service life was short, the tapping flow is scattered and the temperature drop is large, which affected the production efficiency and production cost to a certain extent.

The domestic high aluminum material with integral casting technology was applied to the tapping trough, which overcame the above defects and significantly improved the production efficiency.

⑥ Ladle preheating

The technology of introducting natural Gas for preheating ladle, instead of the previous  preheating ladle with crude oil, improved the preheating efficiency, improved the  workers’labor intensity , and saved costs.

2.2.CCM area

① Lubricant for copper mould

Palm oil was used to replace rapeseed oil. Due to abundant palm oil resources in Africa, a large amount of rapeseed oil from China was saved.

② Nozzle of CCM

Before CCM in the casting process often occurred breaking-out phenomenon, after careful observation and research, Four nozzles in the corner under copper mould are added to solve the problem of breaking-out completely.

2.3.Rolling mill area

① Billet sizing

According to the different specifications of ribbed bars produced by rolling mill, the optimal length of billets was calculated respectively, and the centralized and classified production of billets in rolling mills was arranged, and the yield of billets with different sizes was increased by 4% compared with the previous ones.

② Fuel for preheating furnace

The introduction of preheating technology with natural Gas as the main preheating method, instead of the previous crude oil preheating method, crude oil preheating as a backup heating mode in case of natural gas failure. This technology has also produced good economic benefits.

Through the above series of technical transformation, the production efficiency of the factory was improved, the production cost of the factory was reduced from each link, and considerable economic benefits were created for the factory.

3.Comparison of other relevant technical indicators before and after technical service, see

Table-1

At that time, the power supply in Nigeria was very poor. There were 48 power-cut at the worst time in 24 hours, which was extremely random and had no anticipated planning. Therefore, it was extremely difficult to organize production here. However, the equipment equipped were extremely backward, the degree of automation was low, and the process was relatively backward. In view of this situation, the above series of technical improvement measures were taken to achieve the imported materials and spare parts at the same time, in this backward situation, we could maximize the production potential, optimized some links with cost reduction, and reduced the comprehensive production cost.