1. Continuous casting billet production

The production of continuous casting billets refers to the production of qualified billets within a specified period of time (usually measured in months, seasons, and years). The calculation formula is:

Continuous casting billet output (t)=total production billet quantity - inspection scrap quantity - scrap quantity after rolling or returned by the user.

Continuous casting billets must be produced in accordance with national or ministerial standards, or in accordance with the standards and technical agreements specified in the supply contract.

2. Continuous casting ratio

Continuous casting ratio refers to the percentage of qualified production of continuous casting billets in total steel production. It is one of the important indicators of the level and efficiency of steelmaking production technology, and also reflects the development status of continuous casting production in enterprises or regions. The calculation formula is:

Continuous casting ratio (%)=qualified billet production/total billet production × 100% (1-2)

The total qualified steel production in the above equation is also the sum of qualified continuous casting billet production and qualified steel ingot production; It is calculated based on the qualified quantity in storage.

3. Qualification rate of continuous casting billet

The qualification rate of continuous casting billets refers to the percentage of qualified billets in the total inspection quantity of continuous casting billets. Also known as quality indicators (usually measured in months and years). The calculation formula is:

Total inspection quantity of continuous casting billet=qualified continuous casting billet production+inspection waste quantity+user or rolling waste quantity

(The amount of head and tail cutting of continuous casting billets, replacement of joints in the tundish, and the amount of remaining steel below 300mm in the tundish are not counted as scrap)

4. Yield of continuous casting billet

The yield rate of continuous casting billet refers to the percentage of qualified continuous casting billet production in the total amount of continuous casting molten steel. It accurately reflects the consumption of continuous casting production and the recovery of molten steel.

The total amount of molten steel in continuous casting=qualified continuous casting billet production+scrap quantity+total amount of replaced joints in the tundish+total amount of remaining steel in the tundish+total amount of steel in the ladle after pouring+total amount of remaining steel in the ladle+total amount of drainage loss steel+total amount of sticking steel in the tundish+total amount of cutting head and tail+total amount of oxidation loss steel in the casting process and flame cutting.

The yield of the billet is related to the size of the cross-section. If the cross-section of the billet is small, the yield is lower.

5. Billet yield

If the billet is produced by two fires, the product of the step by step yield can be used as the yield of the entire process.

6. Continuous casting machine operation rate

The operation rate of continuous casting machine refers to the percentage of actual operation time of the casting machine in the total calendar time (generally calculated by monthly, quarterly, and annual statistics). It reflects the start-up operation and production capacity of the continuous casting machine. The calculation formula is:

The actual operating time of the continuous casting machine=the time from the ladle pouring to the completion of cutting (shearing)+the time for the upper dummy bar+the time for waiting for normal pouring preparation (less than 10min)

Increasing the number of continuous casting furnaces, developing rapid replacement of tundish technology and continuous casting technology for different steel grades, shortening preparation time, improving equipment diagnosis technology, reducing continuous casting accidents, shortening troubleshooting time, and strengthening the supply of spare parts can all improve the operation rate of continuous casting machines.

7. Continuous casting machine reaches production rate

The production rate of a continuous casting machine refers to the percentage of the actual production rate of the continuous casting machine to the designed production rate of the continuous casting machine during a certain period of time (usually calculated annually). It reflects the level of equipment performance of this continuous casting machine.

8. Average number of continuous casting furnaces

The average number of continuous casting furnaces refers to the ratio of the number of furnaces for pouring molten steel to the number of times the continuous casting machine has started pouring. It reflects the continuous operation capability of the continuous casting machine. The calculation formula is:

9. Average continuous pouring time

The average continuous casting time refers to the ratio of the actual operating time of the continuous casting machine to the number of times the continuous casting machine is started. It also reflects the continuous operation of the continuous casting machine. The calculation formula is:

10. Casting machine leakage rate

The leakage rate of the casting machine refers to the percentage of steel flow that has leaked from the continuous casting machine during a certain period of time compared to the total flow of the casting machine during that period. The calculation formula is:

During the continuous casting production process, both steel overflow and steel leakage are malignant accidents. They not only damage the continuous casting machine, disrupt normal production order, affect output, but also reduce the operating rate, production rate, and continuous casting furnace number of the casting machine. Therefore, the leakage rate of the casting machine directly reflects the equipment, operation, process, and management level of the casting machine, and is one of the key indicators to measure the efficiency of the continuous casting machine.

11. Casting rate of continuous casting

The casting rate of continuous casting refers to the percentage of successful casting furnaces in the total number of casting furnaces. The calculation formula is:

The number of successful pouring furnaces: Generally, at least 2/3 of the molten steel in a furnace is poured into a billet, which can be considered as the successful pouring of the steel in that furnace.

12. Calculation of other indicators

In addition to the above technical and economic indicators, separate statistics can also be made on some important production, process, and equipment spare parts life parameters that restrict the normal pouring of continuous casting during the production process.

(1) Steel liquid sedation time. The waiting time for the molten steel from the time the ladle leaves the argon blowing or refining position to the start of pouring is the steel quenching time. During the production process, a suitable range of sedation time should be determined based on factors such as the length of the ladle operation route and the heat dissipation of the ladle.

(2) Temperature of molten steel on the continuous casting platform. After the steel ladle reaches the pouring platform, the temperature measured 5 minutes before pouring is the temperature of the continuous casting platform steel liquid. The statistical assessment of this indicator is conducive to maintaining stable pouring of continuous casting within a small temperature range. During production, appropriate temperature control ranges for molten steel should be developed based on factors such as the type of steel poured, the capacity of the ladle and tundish, the cross-section of the continuous casting billet, and the casting speed.

(3) The interval time between steel liquid supply. The interval time between the supply of molten steel can be expressed as the time interval between the completion of the previous ladle pouring, the closure of the water inlet, and the opening of the next ladle water inlet (or the time interval between the arrival of two molten steel packages at the continuous casting platform). It is related to factors such as smelting, refining cycle, and casting speed. It is best to control the interval time within 5 minutes to facilitate stable pulling speed.

(4) The average age of the tundish. The average age of the tundish is also the service life of the tundish. It refers to the ratio of the number of molten steel furnaces poured during a certain period of continuous casting to the number of tundishes used (which can be calculated in monthly, quarterly, and annual time units). The calculation formula is:

In production, the longest safe service life should be determined based on factors such as the nature, quality, capacity, and type of steel poured into the lining refractory material of the tundish,The maximum safe service life of the tundish should be determined based on factors such as the nature, quality, capacity, and steel grade of the refractory material inside the tundish, that is, the maximum allowable pouring time of the tundish. Generally, it is not allowed to exceed the specified number of times of use in normal production.

(5) The service life of the crystallizer. The service life of a crystallizer refers to the working time from the beginning of use to replacement, which is the time the crystallizer maintains its original design parameters. It can be represented by the number of heats poured or the total amount of molten steel during this period. The main reason for replacing the mold is that there is wear and deformation during the casting process, which changes the original design parameters and affects the quality of the casting billet.

In addition, the average service life of the crystallizer can also be calculated on a monthly, quarterly, and annual basis, expressed as the ratio of the amount of steel passing through the copper tube or plate of the crystallizer to the number of crystallizers used.