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# What is the calculation method for the main technical and economic indicators of electric furnace ferroalloy smelting

Posted by: steel world 2023-10-13 Comments Off on What is the calculation method for the main technical and economic indicators of electric furnace ferroalloy smelting

1、 Quality Policy for Electric Furnace Ferroalloy Products
The quality of electric furnace ferroalloy products is a policy that reflects the level of electric furnace ferroalloy products and smelting skills. All products that comply with national standards, ministerial standards, manufacturer standards, and user agreement standards are qualified products.
Qualified and scrap iron alloy products with standard components are accounted for according to the standard quantity.
（1） Qualification rate of electric furnace ferroalloy (referring to the one-time qualification rate)
The qualification rate of electric furnace ferroalloy refers to the percentage of the qualified quantity of the product in the total inspection quantity during the stated period. The calculation formula is:
Qualified rate of ferroalloy products (%)=Qualified quantity of ferroalloy inspection (ton) × 100%
Total amount of ferroalloy submitted for inspection (ton)
Regarding the production of multiple types of manufacturers, it is also necessary to check the overall qualified rate of the factory. The calculation formula is:
Inductive qualification rate of electric furnace ferroalloy (%)=sum of qualified inspection quantities of ferroalloy by type (ton) × 100%
Sum of total inspection amount for different types of ferroalloys (ton)
Accounting clarification:
(l) The product qualification rate should be calculated by type and furnace; The unit of neutron and parent term in the formula is standard tons.
(2) Under normal circumstances, participate in product quality audits immediately after the product is released from the furnace.
(3) Stop and start the furnace:
1) The first batch of products produced by newly opened electric furnaces that have been shut down for more than 36 hours due to major or medium repairs, as well as periodic furnace shutdowns or external reasons, but have resumed production, will not participate in the quality policy audit (except for elite electric furnaces).
The products from the two furnaces of tungsten iron head will not participate in quality inspection.
2) For newly opened or pre shut down furnace cleaning, any waste generated after participating in furnace cleaning will not be counted as furnace number and will not be subject to waste inspection. However, the electricity and materials consumed during the furnace cleaning process should not be deducted and should be included in the consumption policy accounting.
3) Plan maintenance: All waste products that result in continuous power outages of electric furnaces with a voltage of 5000 kVA or above for less than 48 hours due to external reasons from the manufacturer, and shutdowns of electric furnaces with a voltage of 5000 kVA or below for less than 36 hours, will be subject to quality audits.
(4) Product conversion:
1) The furnace material of the former product is useful or at least harmless for the latter product, and the transitional product that occurs only needs to meet the quality standards to be considered qualified. For waste products that do not comply with any brand rules, participate in product quality accounting after conversion.
2) The conversion of different element products (such as silicon chromium conversion to silicon iron conversion) that are harmful to the previous product can be calculated according to the rules of new furnace opening.
3) In principle, the time boundary for converting to refining should be distinguished by the time of material change or the time of iron blockage in the top furnace after material change. If the first batch of products produced meets the quality standards of the products before conversion, the operation time of the products before conversion should be stopped until the time when the first batch of iron is blocked after conversion; If the first batch of products after conversion does not meet the quality standards or the quality standards of the latter product, then the conversion time and power consumption are different based on the material conversion time.
(5) The products produced by the furnace or equipment issues, regardless of whether they are qualified or not, regardless of the quantity, will be recorded with the furnace number and included in the quality policy accounting.
(6) Regardless of equipment conditions, process conditions, and raw material quality, the economic policy of product skills should be accounted for as long as production is required. Products produced during the trial production period of new products (up to 3 months) and the trial production period of new electric furnaces (up to 6 months) may not participate
Check the quality policy and other policies.
(7) Accounting for products beyond the production plan for product conversion: During the smelting process of electric furnaces (including elite electric furnaces), products outside the plan (such as medium chromium produced during the smelting of low-carbon ferrochrome or micro chromium products produced during the production) are stored according to the actual product type and brand, and the output value and output value are calculated. But they will not participate in the accounting of policies such as quality, electricity consumption, and raw material consumption. The electricity and raw materials consumed by these products are deducted from the total consumption.
Method for distinguishing accounting:
l) Elite products can be differentiated and calculated based on the electricity consumption in front of the furnace, smelting time, and raw material ratio recorded in the “Smelting Record Card”.
2) Other ferroalloy products, due to their continuous production characteristics, can only be differentiated and accounted for using the coefficient method.
Differentiate various costs and work hours by coefficient
For example, in a certain month, a certain electric furnace produced 120 tons of special ferrosilicon, bringing out 10 tons of 75% ferrosilicon, consuming a total of 1560000 kilowatt hours of electricity, 325 tons of ore, and 696 hours of practical operation time per month. The difference in accounting process is as follows:
Calculate coefficient:
75% ferrosilicon=10=0.0769
120 tons+10 tons
（2） Scheme brand compliance rate
The compliance rate of the scheme brand refers to the percentage of the practical output value of the scheme brand that matches the product output value of the scheme rule brand. It reflects the degree to which the ferroalloy smelting policy is targeted, as well as the operational level of smelting skills of ferroalloy workers. The calculation formula is:
Matching rate of scheme grade (%)=actual output value of matching scheme grade (ton) × 100%
Product output value of scheme rule brand (ton)
Accounting clarification:
(l) The scheme designation includes the chemical composition requirements of the scheme rules.
(2) The compatibility rate of scheme brand should be calculated by brand and filled in by category; The unit of neutron and parent term in the formula is standard tons.
(3) The practical output value (sub items) of the matching scheme brand are not offset between the brand and type, that is, when the practical output value of the matching scheme brand is less than the planned output value of the brand, it is calculated based on the practical quantity; When the practical output value of the matching scheme brand is greater than the scheme output value of that brand,
The excess part will not be counted. The policy value is not greater than 100%.
(4) The sub items and parent items for calculating the compliance rate of the overall factory’s summary plan brand are the sum of the sub items and parent items for the compliance rate of each type of plan brand. [next] 2、 Unit product electricity consumption and process energy consumption
Unit product electricity consumption (referred to as “unit electricity consumption”) refers to the electricity consumption required to produce 1 ton of qualified ferroalloy during the stated period. The calculation formula is:
Unit product electricity consumption (kWh/ton)=total product electricity consumption (kWh)
Qualified product output value (ton)
Electricity consumption per unit product smelting (kWh/ton)=total electricity consumption per product smelting (kWh)
Qualified product output value (ton)
Accounting explanation: The parent unit in the formula is standard tons.
The total electricity consumption of the product includes the electricity consumption during the smelting process and the electricity for drying, washing, power, lighting, etc. during the production of the product. The total electricity consumption of product smelting includes the electricity consumption and furnace washing electricity during the product smelting process.
The active energy meter of the electric furnace should be calibrated with a standard electricity meter on the external surface of the power laboratory within the regular date of each month, and adjusted based on the verified positive and negative error coefficients for the current month. The calculation formula is:
After verification, the total electricity consumption of smelting (kW · h)=the electricity consumption of the electric furnace × (1- (Errors at the beginning of the month and errors at the end of October)/2)
Accounting clarification:
(l) The newly opened oven power refers to the amount of electricity consumed from the beginning of the oven power transmission to the front of the top furnace iron block, which should be deducted from the total electricity consumption.
(2) Due to external reasons (such as power restrictions, material shortages, natural disasters, etc.), a continuous power outage of more than 48 hours for electric furnaces with a voltage of 5000 kVA or above, and a continuous power outage of more than 36 hours for electric furnaces with a voltage of less than 5000 kVA (excluding elite electric furnaces),
When calculating the electricity consumption of product smelting, it should be deducted. The baking furnace electricity consumed by electric furnaces with a continuous power outage of 5000 kVA and above for less than 48 hours, and electric furnaces with a continuous power outage of less than 5000 kVA for less than 36 hours, should not be deducted when calculating the electricity consumption of product smelting.
(3) The baking electricity consumed by the refined electric furnace after lining replacement and the continuous power outage caused by external reasons for more than 24 hours shall be deducted when calculating the electricity consumption of product smelting. The calculation formula is:
Oven power (kW · h)=Plan uniform power × (Two furnace uniform smelting time – monthly uniform furnace smelting time)
(4) The energy consumption per unit process of electric furnace ferroalloy is calculated by referring to the calculation formula for energy consumption per unit process of steelmaking.
3、 Primary raw material consumption per unit product
Unit product raw material consumption (referred to as material consumption) refers to the uniform consumption of a certain amount of raw materials per unit product, indicated by the total amount (dry weight) and equivalent amount of raw materials. It is the basis for formulating raw material plans and reviewing the implementation of consumption quotas. Its accounting formula
For:
Unit product raw material consumption (kg/ton)=actual raw material consumption (dry weight) kg
Qualified product output value (ton)
Equivalent amount of raw material consumption per unit product (dry grams/ton)=actual raw material consumption (equivalent amount) kg
Qualified product output value (ton)
Accounting clarification:
(l) The practical consumption of raw materials refers to the number of furnace inputs. Excluding inventory, transit, on-site, and processing losses.
(2) The calculation of unit consumption is limited to products that have been officially put into production. The unit consumption policy is not calculated for new products, scientific research products, and products that have been tested and produced during the trial production stage.
(3) When calculating the consumption of raw materials, it is necessary to list the primary raw materials (including semi-finished products used), including their furnace grade, moisture content, and place of origin.
(4) Calculate the dry weight of the furnace material after removing moisture.
(5) All raw materials consumed during the furnace cleaning process will not be deducted.
(6) The raw material consumption per unit product calculated based on the converted amount is:
1) Chromium ore is converted to 45% based on its Cr2O3 content;
2) Manganese ore (containing rich manganese slag): smelting manganese silicon alloy and high carbon manganese iron is converted into 32% manganese content; Smelting medium and low carbon ferromanganese is equivalent to 38% manganese content.
(7) The parent unit in the formula is standard tons. [next] 4、 Recovery rate of primary element smelting
The recovery rate of primary element smelting refers to the degree of use of a certain primary element in the smelting process of a product. It is a policy that reflects the degree of metal recovery during the smelting process. The calculation formula is:
Recovery rate of primary element smelting (%)=qualified product containing primary element component (ton) × 100%
The primary element content of the incoming material (ton)
Accounting clarification:
(1) For products produced in several steps of the process, the total recovery rate should be equal to the product of the recovery rates in each step.
(2) The waste alloy or alloy powder purchased by the manufacturer (including cross furnace) should be listed for accounting unit consumption and included in the calculation of alloy element recovery rate.
(3) Regarding composite iron alloys, such as manganese silicon, silicon chromium, etc., only the primary element between them is selected for accounting. The principle for distinguishing between primary and secondary elements is:
1) Proportion in product composition:
2) The degree of nobility of elements.
(4) The calculation formula for the recovery rate of carbon manganese and medium manganese using the flux free method should include the primary element content in the slag, while the parent term remains unchanged × The utilization rate of primary elements in slag.
5、 Labor output rate of workers
The labor output rate of workers refers to the uniform quantity of ferroalloys produced by each worker and apprentice during the reporting period. It indicates the production ability of workers at a certain time. The calculation formula is:
Labor output rate of workers (tons/person)=qualified product output value (tons)
Average number of workers and apprentices (person)
Accounting explanation: This formula is applicable to independent ferroalloy factories. Regarding non independent ferroalloy workshops (or electric furnaces), it should be noted that the product output value is consistent with the scale of workers producing the product; The unit of the neutron term in the equation is standard tons.
6、 Calendar usage coefficient of electric furnace
The calendar utilization coefficient of the electric furnace refers to the qualified ferroalloy output value per unit transformer additional capacity (megavolt ampere) of the electric furnace during the calendar time period, which is uniform and daily. It reflects the degree of use and operational level of electric furnaces, as well as the management level of manufacturers. The calculation formula is:
Calendar usage coefficient of electric furnace (ton/MVA · day)=qualified product quantity (ton)
Transformer Additional Capacity (MVA) × Calendar days (days)
Accounting clarification:
(1) The calendar usage coefficient of electric furnaces should be calculated by type and electric furnace, and the unit of sub items in the formula is standard tons.
(2) The capacity of the transformer should be calculated based on the additional quantity of the nameplate; The capacity of the transformed transformer is calculated based on the measured practical capacity.
7、 Uniform daily production value
The uniform daily output value reflects the production capacity of the electric furnace that is evenly delivered every day during the stated period. The calculation formula is:
Uniform daily production value (tons/day)=Qualified product production value (tons)
Number of practical homework days (days)
Accounting clarification: The number of practical homework days should be consistent with the guidelines for homework rates; The unit of the neutron term in the equation is standard tons.
8、 Calendar operation rate of electric furnace
The calendar operation rate of electric furnaces refers to the percentage of practical operation hours of electric furnaces in calendar hours. It is a policy that reflects the degree of use of electric furnaces at all times. The calculation formula is:
Calendar operation rate of electric furnace (%)=practical operation time (hours) × 100%
Calendar time (hours)
Accounting clarification:
(l) Practical homework time refers to the calculation from the time of power supply to the electric furnace, which should include necessary auxiliary time (such as voltage change, electrode discharge, and power outage time for refined electric furnace tapping).
(2) The sub and parent items for calculating the calendar operation rate of electric furnaces summarized by the entire factory are the sum of the sub and parent items for each electric furnace operation rate. [next] 9、 Life expectancy of elite electric furnace lining
The lifespan of the elite electric furnace lining refers to the number of furnaces for smelting ferroalloys with each replacement of the lining. It reflects the degree of use of refractory materials in the furnace lining, the quality of refractory materials and furnace construction, operation, and the protection of the furnace lining. The calculation formula is:
Elite electric furnace lining life (furnace)=total number of ironing furnaces (furnace)
Times of replacing furnace lining (times)
Accounting clarification:
1) From the time the furnace lining is put into use to the time when a new lining is replaced, it is considered as one furnace service. During this period, the number of furnaces for smelting ferroalloys is called the “furnace life”.
(2) The elite electric furnace lining, regardless of the degree of repair, only needs to be replaced and repaired, and is calculated as a replacement once.
10、 Uniform power of electric furnace
The uniform power of an electric furnace (i.e., the ability to work uniformly) refers to the useful power output by the transformer during practical operation of the furnace. Compared with the additional capacity of the transformer, it can accurately reflect the degree of utilization of the electric furnace during the operation time. The calculation formula is:
Uniform power (kW)=total smelting power consumption (kW · h)
Practical homework hours
Accounting clarification:
(1) The total electricity consumption for smelting should include electricity for baking and washing.
(2) The practical homework time should be shared with the sub item for calculating the calendar homework rate of the electric furnace.
11、 Electric furnace ferroalloy slag iron ratio
The slag to iron ratio is a policy for investigating the size of slag. Choosing a reasonable slag type is a key skill in ferroalloy smelting operations.
The slag iron ratio refers to the ratio of actual slag production to actual iron production. The amount of slag generated per ton of iron produced. The calculation formula is:
Slag iron ratio (ton/ton)=total slag amount (ton)
Total iron production (ton)
Accounting Explanation: The total amount of iron produced includes scrap, and is calculated based on the actual quantity.

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