Multi-gun top-blowing converting furnace slag type control method

Abstract

The invention discloses a multi-lance top-blown converting furnace slag type control method, which comprises the following steps of: quickly and accurately analyzing key data such as copper content, silicon content and calcium-iron ratio of top-blown converting furnace slag within 5 minutes by virtue of an on-site quick analysis means, and calculating the total oxygen amount of an oxygen lance, the quartz addition amount and the limestone addition amount adjustment value by virtue of a mathematical model; therefore, key data such as slag copper content, slag silicon content, calcium-iron ratio and the like are accurately regulated, the magnetic iron content in the slag is synchronously regulated, slag adhering on the side wall of the hearth is promoted, the hearth is protected, and the service life of the hearth is prolonged. According to the method, the furnace condition is rapidly and accurately grasped, the converting slag type is accurately regulated and controlled, safe, stable and production are achieved, meanwhile, directional regulation and control of magnetic iron in the converting slag are achieved, therefore, slag adhering of a hearth is promoted, the service life of the hearth is prolonged, the consumption of lime and oxygen is reduced as much as possible, and the cost reducing and efficiency improving potential of the multi-lance top converting copper technology is deeply excavated.

Description

Technical Field

[0001] This invention belongs to the field of metal smelting technology, specifically relating to a method for controlling the slag type in multi-lance top-blown smelting furnaces. Background Technology

[0002] The "side-blown smelting + top-blown smelting" technology, as a typical representative of technological innovation in molten pool smelting, has been successfully applied in many enterprises. The actual maximum annual output of cathode copper by a single system of this technology can exceed 450,000 tons, and the maximum annual cathode copper production capacity in China has exceeded 2.5 million tons. The "side-blown smelting + top-blown smelting" process has low investment costs, low requirements for raw materials, strong impurity removal capabilities, and high operating rates. Currently, the processing cost per ton of crude copper is only over 800 yuan. However, it still has problems such as high dependence of each system, which makes it easy to shut down, difficulty in furnace condition control, which easily leads to foamy slag, and high dependence on experience, which makes it difficult to automate.

[0003] The multi-lance top-blown smelting furnace is a crucial component of the "side-blown smelting + top-blown smelting" process. Multiple non-submerged oxygen lances are installed on the furnace top, with the oxygen lances blowing at a height of 100-400 mm above the melt surface. Continuous production can be achieved by replacing faulty oxygen lances online. Because copper matte flows into the multi-lance top-blown smelting furnace via a chute without accurate metering, the furnace exhibits large fluctuations in furnace conditions and is prone to foamy slag. Determining the oxidation endpoint of crude copper plays a decisive role in the furnace condition control of the multi-lance top-blown smelting furnace and is key to preventing foamy slag. Furthermore, controlling the oxidation endpoint of crude copper is essentially controlling the slag type in the smelting furnace.

[0004] The current methods for controlling the slag pattern in multi-lance top-blown smelting furnaces mainly include observing copper slag samples, observing changes in the slag-copper surface and slag-copper separation by sizing, analyzing slag samples taken from the slag nozzle and sizing, and observing data from boiler outlet sulfur dioxide concentration, residual oxygen concentration, and boiler steam volume. During production, adjustments are made to the furnace temperature, total oxygen injection into the oxygen lance, and the addition of limestone and quartz, etc., based on the real-time changes in these control measures. Currently, most enterprises use copper slag sampling as the primary basis for controlling the multi-lance top-blown smelting furnace. However, analyzing slag samples taken from the slag nozzle and sizing has a significant time lag, making it difficult to quickly and accurately control the slag pattern. Therefore, it is not used as the primary basis for furnace condition control, but rather for parameter feedback adjustments. Sizing relies entirely on experience, which is difficult to judge and lacks standardized judgment criteria. Summary of the Invention

[0005] To address the limitations of existing slag shape adjustment methods, this invention provides a slag shape control method for multi-gun top-blown blast furnaces, enabling rapid, precise, and directional control of blast furnace slag shape.

[0006] This invention is achieved through the following technical solution: A method for controlling the slag type in a multi-gun top-blown smelting furnace includes the following steps: S1: On-site sampling is conducted during the blowing process, with a sampling frequency of 0.25 to 6 hours / time. The blowing slag with uniform distribution on the measuring tape or slag mouth is selected as the sample. After cooling, it is crushed using a sample mill. The mass fraction of Cu, SiO2, Fe, CaO, etc. in the slag sample is analyzed. At the same time, the sample data is automatically corrected by using the standard curve calibrated by the standard sample. S2: Based on the corrected data, the adjustment values ​​of the total oxygen content of the oxygen lance, the amount of quartz added, and the amount of limestone added are calculated according to the mathematical model. Finally, the copper content in the blowing furnace slag is controlled at 15-30 wt%, the silicon content at 0-3.5 wt%, and the calcium-iron ratio at 0.2-0.4.

[0007] This invention enables rapid and accurate blowing slag testing results within 10 minutes through manual sampling, on-site sample grinding, or the use of a complete set of analytical equipment, without altering the existing main process, equipment, or furnace structure. Then, using a mathematical model, theoretical calculations are performed based on the test results to provide adjustment values ​​for the total oxygen content of the oxygen lance, the amount of quartz added, and the amount of limestone added, thereby achieving rapid, precise, and directional control of the blowing slag pattern. Simultaneously, it can continuously monitor magnetic iron to promote slag adhesion in the furnace and improve furnace life, thus ensuring the safe and stable operation of the furnace.

[0008] Preferably, the analytical method in step S1 is X-ray fluorescence spectrometry.

[0009] Preferably, the total oxygen content of the oxygen lance is adjusted according to the mass fraction of Cu in the slag sample.

[0010] Preferably, the amount of quartz added is adjusted according to the mass fraction of SiO2 in the slag sample.

[0011] Preferably, the amount of limestone added is adjusted according to the mass fraction ratio of Fe and CaO in the slag sample.

[0012] Preferably, during sample analysis, relevant calculations are performed using an Excel spreadsheet constructed with a mathematical calculation model, and the spreadsheet data is updated according to changes in various parameters.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention can quickly and accurately analyze data such as copper content, silicon content, and calcium-iron ratio in top-blown furnace slag. Then, it uses a mathematical model to calculate adjustment values ​​such as total oxygen content in the deaerator, quartz addition, and limestone addition. Through precise calculation, it can minimize the consumption of lime and oxygen, thereby achieving precise control of key data such as copper content, silicon content, and calcium-iron ratio in the slag, and ultimately achieving the goal of controlling the slag type.

[0014] 2. This invention can simultaneously adjust the content of magnetic iron in slag, promote slag adhesion on the furnace sidewall to protect the furnace and extend its lifespan, and achieve directional control of magnetic iron in slag while realizing safe and stable production, thereby reducing costs and increasing efficiency in multi-gun top-blown copper smelting process. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0016] The present invention will be further described below with reference to the embodiments. Unless otherwise specified, the technical means used in the embodiments are all conventional technical means in the art. Example 1

[0017] A method for controlling the slag type in a multi-gun top-blown smelting furnace includes the following steps: S1: On-site sampling is conducted during the blowing process, with a sampling frequency of 0.25h / time. The blowing slag with uniform distribution on the slag gauge or slag mouth is selected as the sample. After cooling, it is crushed using a sample mill. The mass fraction of Cu, SiO2, Fe, CaO, etc. in the slag sample is analyzed. At the same time, the sample data is automatically corrected by using the standard curve calibrated by the standard sample. S2: Adjust the total oxygen content of the oxygen lance based on the Cu content in the slag obtained from laboratory analysis. Calculation of oxygen consumption per unit volume in the top-blown smelting furnace: Assuming the copper matte contains 74.0 wt% copper, 3.0 wt% iron, and 20.5 wt% sulfur, with a matte production of 60 tons, and all iron is calculated as Fe₂O₃, then each ton of Fe requires 300 Nm³ of oxygen. If all sulfur is calculated as SO₂, then each ton of S requires 700 Nm³ of oxygen. The smelting slag contains 35.0 wt% iron and 26.0 wt% copper, then the slag production per ton of copper matte = 3% ÷ 35% = 0.086 tons, and the amount of copper to be oxidized is 26% × 0.086 t = 0.02236 tons. If all copper is calculated as Cu₂O, then each ton of Cu requires 87.5 Nm³ of oxygen. Therefore, the oxygen consumption per ton of copper matte is approximately 154.5 Nm³ = 3% × 300 + 20.5% × 700 + 0.02236 × 87.5 Nm³. Assuming an oxygen enrichment concentration of 30% and a residual oxygen level of 2% at the boiler outlet, the total air volume required per hour for blowing is 154.5 × 60 ÷ (30% - 2%) = 33107 Nm³. After increasing the oxygen consumption by 5 units, the total air volume required is 159.5 × 60 ÷ (30% - 2%) = 34178 Nm³. If the current slag contains 20.0 wt% copper, and other parameters remain unchanged, to increase the copper content to 26.0 wt% would require oxygen consumption of (26% - 20%) × 76 (slag line area) × 0.3 (slag layer thickness) × 5 (blown slag density) × 87.5 = 598.5 Nm³. The required oxygen consumption per unit area would be 598.5 Nm³ ÷ 60 ≈ 10 Nm³, and the total air volume would increase by 10 × 60 ÷ (30% - 2%) = 2142 Nm³. The above figures represent the increased air volume within 1 hour under unchanged conditions. If the slag needs to be blown over within 0.5 hours, both the oxygen consumption per unit area and the air volume should be doubled.

[0018] S3: Adjust the amount of quartz added during blowing based on the SiO2 content in the slag obtained from the chemical analysis. The target slag silicon content is 2.0 wt%, the current slag silicon content is 1.0 wt%, the original slag layer thickness is 400 mm, and the copper matte contains 0.1 wt% silicon. The remaining calculation conditions are the same as before. The slag production per ton of copper matte blowing = 3% ÷ 35% = 0.086 t, the original slag amount = 76 × 0.4 × 5 = 152 t, then the amount of quartz to be added per hour = (152 + 0.086 × 60) × 0.02 - 152 × 0.01 - 60 × 0.1% = 1.56 t.

[0019] S4: Adjust the amount of limestone added during blowing based on the Fe and CaO content in the slag obtained from laboratory analysis. First, determine the theoretical amount of limestone added = copper matte production × iron content in copper matte × target calcium-iron ratio (calcium-iron ratio is the ratio of CaO to Fe mass fraction) ÷ 56 × 100 × 1.1 (t / h). Second, make a feedback adjustment based on the Fe and CaO content in the slag: limestone addition amount = target calcium-iron ratio ÷ current calcium-iron ratio × current limestone addition amount (t / h). For example, if the current calcium-iron ratio is 0.25, the target is 0.30, and the current limestone addition amount is 1.2 t / h, then the limestone addition amount = 0.3 ÷ 0.25 × 1.2 = 1.44 t / h ≈ 1.5 t / h. Example 2

[0020] This embodiment is a further improvement based on Embodiment 1, as detailed below: During the blowing process, on-site sampling is conducted every 6 hours. Simultaneously, an Excel spreadsheet is created for calculation, and the spreadsheet is updated based on changes in the test data. Rapid analysis of the elemental content of the blowing slag is completed within 5 to 10 minutes. Then, within 1 to 2 minutes, the adjustment values ​​for the total oxygen content of the oxygen lance, the amount of limestone added, and the amount of quartz added are calculated and adjustment instructions are issued, achieving rapid, accurate, and directional control of the blowing slag type.

[0021] The magnetic iron content is analyzed rapidly every 2 hours. The copper, calcium-iron ratio and silicon content of the blowing slag are adjusted according to the magnetic iron content in the slag. The magnetic iron content is controlled at 30-50%. This ensures that the slag is fully coated in the furnace while maintaining good slag fluidity and ensuring that there are no abnormalities in the slag discharge and slag-copper separation process.

[0022] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A method for controlling slag type in a multi-gun top-blown smelting furnace, characterized in that, Includes the following steps: S1: On-site sampling is conducted during the blowing process, with a sampling frequency of 0.25-6 hours / time. The blowing slag with uniform distribution on the slag gauge or slag opening is selected as the sample. After cooling, it is crushed using a sample mill. The mass fraction of Cu, SiO2, Fe, CaO, etc. in the slag sample is analyzed. At the same time, the sample data is automatically corrected using the standard curve calibrated by the standard sample. S2: Based on the corrected data, the adjustment values ​​of the total oxygen content of the oxygen lance, the amount of quartz added, and the amount of limestone added are calculated according to the mathematical model. Finally, the copper content in the blowing furnace slag is controlled at 15-30 wt%, the silicon content at 0-3.5 wt%, and the calcium-iron ratio at 0.2-0.

4.

2. The method for controlling slag shape in a multi-gun top-blown smelting furnace according to claim 1, characterized in that: The analytical method in step S1 is X-ray fluorescence spectrometry.

3. The method for controlling slag shape in a multi-gun top-blown smelting furnace according to claim 1, characterized in that: The total oxygen content of the oxygen lance is adjusted according to the mass fraction of Cu in the slag sample.

4. The method for controlling slag shape in a multi-gun top-blown smelting furnace according to claim 1, characterized in that: The amount of quartz added is adjusted according to the mass fraction of SiO2 in the slag sample.

5. The method for controlling slag shape in a multi-gun top-blown smelting furnace according to claim 1, characterized in that: The amount of limestone added is adjusted according to the mass fraction ratio of Fe and CaO in the slag sample.

6. The method for controlling slag shape in a multi-gun top-blown smelting furnace according to claim 1, characterized in that: During sample analysis, relevant calculations are performed using an Excel spreadsheet constructed with a mathematical calculation model, and the spreadsheet data is updated based on changes in various parameters.

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