Electrolytic Production Of Aluminum Research Articles

Aluminum exposure levels in workers at electrolytic production

Introduction. Occupational exposure to aluminum has been established to lead to accumulation of metal in tissues and create a risk of functional impairment in the central nervous system. The aim of the work was to assess the levels of external and internal aluminum exposure in workers at the electrolytic production of aluminum under modern occupation conditions. Materials and methods. Two hundred fifty measurements of the average shift aluminum oxide concentration were analyzed at various stages of the technological process. The urine aluminum concentration urine was determined by the atomic absorption method. Results. The aluminum oxide concentration in the housings with the unbaked anode technology varied from 0.59 to 17.95 mg/m3. The MPC was exceeded at the electrolyzer workplace in 10% of measurements, the anode maker — in 40%, and the crane operator – in 50%. In housings with a baked anode, the aluminum oxide concentration in all measurements did not exceed the MPC. The highest aluminum emission was observed in occupational groups associated with unbaked anodes. A trend model was constructed for the dependence of urine aluminum concentration on the aluminum dioxide level in the air, which has the form of an exponential curve. The bend in the curve begins with an air aluminum dioxide content of about 4.2 mg/m3. Limitations. The study is limited by the number of examined workers who underwent periodic medical examination. Conclusion. The results of biomonitoring showed the elimination of aluminum with urine to reflect the level of exposure to the toxicant. The equation of the dependence of the urine aluminum concentration on the air aluminum dioxide level was calculated.

Anode process on gold in KF–AlF<sub>3</sub>–Al<sub>2</sub>O<sub>3</sub> melt

In the conditions of resource saving and carbon footprint reduction, the development of oxygen–releasing anodes for technologies of production of important metals and alloys by electrolysis of molten salts seems to be an urgent task. To determine the degree of “inertness” of a particular anode material, data on the kinetics and mechanism of the anode process on a material not subject to oxidation are required. In this connection, the anodic process on gold in the KF–AlF3–Al2O3 melt for electrolytic aluminum production was investigated by cyclic and square–wave voltammetry methods. The influence of temperature (715 and 775 оC) of the melt, the content of Al2O3 in it (from 0.1 to saturation), as well as the polarization rate (0.05–1 V/s) on the kinetics and some features of the mechanism of the investigated process was determined. An assumption is made that oxygen release on gold without dissolution of the substrate takes place in the region of overvoltages from 0 to 0.8 V. It is shown that the process includes the stages of electrochemical adsorption and desorption of the intermediate product, the first of which is limited by the diffusion of electroactive anions to the anode.

Unidirectional self-actuation transport behavior of metallic aluminum nanodroplets on SiO2/Fe surfaces

To address the issue of adhesion between liquid aluminum and the inner wall of the vacuum ladle during aluminum electrolysis production, molecular dynamics simulations are used to study the self-actuation behavior of aluminum droplets on the refractory materials SiO2 or Fe. Aluminum droplets are separated from the SiO2 surface by their self-actuation behavior in order to solve the issue of aluminum liquid adhesion to the inner wall. Furthermore, the impact of temperature, size, and wedge angle on the self-actuation behavior of droplets is investigated. The results show that droplet self-actuation is not possible when the droplet temperature is below 900 K. However, when the droplet temperature exceeds 900 K, the speed of droplet motion increases with the temperature rise. Within the radius range of 25 Å–32.5 Å, smaller droplet sizes are more advantageous for the self-actuation behavior of the droplets. The displacement of a droplet on a wedge-shaped wetting gradient substrate is significantly greater than on a rectangular wetting gradient. Additionally, the initial velocity of the droplet's motion increases with the wedge angle. However, a larger wedge angle leads to a decrease in the final displacement of the droplet. The results of the study will offer a new method to address the issue of adhesion between liquid aluminum and the inner wall of the vacuum ladle.

Multi-Objective Optimization of Cell Voltage Based on a Comprehensive Index Evaluation Model in the Aluminum Electrolysis Process

In the abnormal situation of an aluminum electrolysis cell, the setting of cell voltage is mainly based on manual experience. To obtain a smaller cell voltage and optimize the operating parameters, a multi-objective optimization method for cell voltage based on a comprehensive index evaluation model is proposed. Firstly, a comprehensive judgment model of the cell state based on the energy balance, material balance, and stability of the aluminum electrolysis process is established. Secondly, a fuzzy neural network (FNN) based on the autoregressive moving average (ARMA) model is designed to establish the cell-state prediction model in order to finish the real-time monitoring of the process. Thirdly, the optimization goal of the process is summarized as having been met when the difference between the average cell voltage and the target value reaches the minimum, and the condition of the cell is excellent. And then, the optimization setting model of cell voltage is established under the constraints of the production and operation requirements. Finally, a multi-objective antlion optimization algorithm (MOALO) is used to solve the above model and find a group of optimized values of the electrolysis cell, which is used to realize the optimization control of the cell state. By using actual production data, the above method is validated to be effective. Moreover, optimized operating parameters are used to verify the prediction model of cell voltage, and the cell state is just excellent. The method is also applied to realize the optimization control of the process. It is of guiding significance for stabilizing the electrolytic aluminum production and achieving energy saving and consumption reduction.

A method of evaluating cell state based on data augmentation and ViT16

In this paper, based on the model of data augmentation and Vision Transformer 16 (ViT16), a method of assessment for electrolysis cell state is presented to get the real-time information of the current cell state, so as to improve current efficiency of process. Firstly, in order to solve the issue of the small sample data and improve classification accuracy, the method of data augmentation is performed on the flame hole images by using convolutional block attention module to improve auxiliary classifier generativhyhee adversarial network. Secondly, the deep feature data of the flame hole images is extracted by the method of ViT16, and the genetic algorithm is applied to eliminate the redundant feature data to improve the accuracy. Thirdly, the support vector machines model is employed to classify the feature data, and the aluminum cells are classified into cold, hot, and normal. Finally, the actual data are applied to the experiments of the above method, the results of experiments show that this method is better than other methods, and the accuracy of classifying the cell state is as high as 98.677%. This is of great significance for the guidance of aluminum electrolysis production process.

Purification of graphite from spent carbon cathodes through the reduction of the mechanical entrainment of cryolite using polyaluminium chloride as a flocculant

Spent carbon cathodes (SCCs) generated during electrolytic aluminum production pose significant environmental hazards. To optimize resource utilization, flotation is used as an early process for the clean recovery of valuable graphite from waste cathodes. However, the mechanical entrainment in flotation restricts the further improvement of product purity, resulting in an increase in waste gas and wastewater discharge in the subsequent purification process. In this study, to increase the fixed carbon content of flotation products, flocculant was first applied to the flotation separation of SCCs, and polyaluminum chloride (PAC) was used to flocculate cryolite with high impurity content to reduce mechanical entrainment in the flotation process. Zeta potential measurements, particle size analysis, optical microscopy, and scanning electron microscopy confirmed the agglomeration of cryolite under the action of PAC. Additionally, the DLVO (Derjaguin, Landau, Verwey, and Overbeek) theory was used to estimate the interaction energy to further explain the mechanism underlying cryolite agglomeration. Interaction energy calculation revealed that the attraction energy between particles was dominant at the PAC concentration of 2000 mg/L. Flotation experiments indicated that under a constant pulp pH of 7.8, the absence of sodium silicate, and a stirring speed of 1200 rpm, mechanical entrainment decreased from 91.53 ± 1.53 g/L to 69.80 ± 1.90 g/L, and the carbon grade of the product increased from 83.07 ± 0.28% to 88.94 ± 0.30%. Overall, the proposed purification method provides a new approach for the efficient recovery of graphite in waste cathodes, which is of great significance for the sustainable development of graphite resources.

A dynamic graph structure identification method of spatio-temporal correlation in an aluminum electrolysis cell

The dynamic correlation analysis of cell-spatial information (distributed anode current signal, DACS) is of great significance in the regional-refined control of industrial aluminum electrolysis cell. Due to the strong-dynamic spatio-temporal correlation of DACS and the complex dynamic cell noise, the existing methods are difficult to effectively obtain the spatio-temporal correlation analysis results of aluminum electrolysis cell. To solve these problems, a dynamic graph structure identification method of spatio-temporal correlation (DGSI-StC) in an aluminum electrolysis cell is proposed. The identified dynamic graph structure is used to describe the dynamic correlation analysis results of cell-spatial information. Specifically, a novel strongly robust distance function Edit Distance on Real sequences with Adaptive threshold (At-EDR) is proposed to weaken the impact of complex dynamic cell noise on the dynamic correlation analysis of cell-spatial information. Under the guidance of aluminum electrolysis process mechanism knowledge, the matrix-representation of dynamic cell noise information obtained from production data is used as the adaptive threshold of At-EDR to construct the dynamic graph structure. Then, based on the single-layer classical graph convolutional network, a framework for optimizing the dynamic graph structure is designed to capture the strong-dynamic spatio-temporal correlation of DACS. The framework obtains the optimal dynamic graph structure by optimizing the hyper-parameters. Finally, the experimental results on the public datasets show that the robustness of At-EDR is superior to existing methods. Meanwhile the experimental results on multiple sets of industrial aluminum electrolysis production datasets show that DGSI-StC improves the classification accuracy by 2.82% compared with existing classification methods.

Preparation of aluminum fluoride from carbon residue in aluminum electrolysis cell by roasting-leaching method

The carbon residue is a hazardous waste generated by the aluminum electrolysis production process, which contains a large amount of electrolyte fluoride salts. In order to recover the electrolyte components in carbon residue, this paper proposes a new method of using carbon residue to prepare aluminum fluoride by converting Na5Al3F14 and Na3AlF6 in carbon residue into aluminum fluoride to realize the recycling of fluoride in carbon residue. In the initial step, optimal parameters for carbon removal during roasting have been determined, including an oxygen flow rate of 7 g/min, a roasting temperature of 670 °C, and a roasting time of 80 min. The roasted clinker is obtained, and the removal rate of carbon reaches 99.95 % while the loss rate of fluorine is 0.48 %. In the second step, the mix anhydrous Al2(SO4)3 with roasted clinker for roasting. The optimal roasting temperature of 670 °C, the time of 10 min, and the mass ratio of anhydrous Al2(SO4)3 to roasted clinker of 5:5 could convert fluoride to AlF3 products, with a conversion rate of 99.76 % and a loss rate of fluorine of 1.05 %. Finally, by removing sulfate impurities through water leaching for 15 min at 35 °C and with a liquid-solid ratio of 6 ml/g, the loss rate of fluorine is 3.98 %. This process yields AlF3 with a purity of 94.30 %. The recovery rate of fluorine in the whole process is 94.56 %, which successfully achieves the recycling of fluorine in the carbon residue to obtain AlF3 products.

Mechanism for leaching of fluoride ions from carbon dross generated in high-temperature and low-lithium aluminum electrolytic systems

Carbon dross, a hazardous solid waste generated during aluminum electrolysis, contains large amounts of soluble fluoride ions for the main components of the electrolyte (such as Na3AlF6 and NaF). Response surface methodology (RSM) was used to investigate the mechanism for fluoride ion leaching from carbon dross via water leaching, acid leaching and alkali leaching, and the kinetic and thermodynamic principles of the leaching process were revealed. The RSM predicted the optimum conditions of water leaching, alkali leaching and acid leaching, and the conditions are as follows: temperature, 50 °C; shaking speed, 213 r·min-1; particle size, 0.075 mm; shaking speed, 194 r·min-1; liquid-solid ratio, 12.6 mg·L-1; sodium hydroxide concentration, 1.53 mol·L-1; liquid-solid ratio, 25.0 mg·L-1; sulfuric acid concentration, 2.00 mol·L-1; and temperature, 60 °C，and actual results which were almost consistent with the predicted results were gained. The fluoride ions in the alkaline and acid leaching solutions were mainly the dissociation products of fluorides such as Na3AlF6, Na5Al3F14 and CaF2, as indicated by thermodynamics calculations. In particular, the fluoride compounds dissolved in alkali solution were Na3AlF6, Na5Al3F14, AlF3, ZrF4, K3AlF6, while the acid solution could dissolve only Na3AlF6 and CaF2. The leaching kinetics experiments showed that the leaching rate fit the unreacted shrinking core model [1–2/3α-(1-α)2/3 =kt] and that the leaching process was controlled by internal diffusion. This study provides theoretical guidance for the removal of soluble fluoride ions from carbon dross and will also assist in the separation of electrolytes from carbon dross. Environmental ImplicationCarbon dross, a hazardous waste generated during the aluminum electrolysis production process, contains a large amount of soluble fluoride. Improper storage will lead the fluoride ions pollution in soil, surface water or groundwater under the direct contact between carbon dross and rainfall, snow or surface runoff. The influence of wind will cause carbon dross dust to pollute further areas. With the human body long-term contact with fluoride ion contaminated soil or water, human health will be seriously harmed.

Reducing the environmental impact of aluminum production through the use of petroleum pitch

This study is aimed at developing a technology for obtaining petroleum pitch as a binder for anode mass used in the electrolytic production of aluminum from fuel oils of catalytic liquid-phase oxidative oil cracking. A review of published data on the existing methods for obtaining petroleum pitch and its properties is carried out in order to define research directions. A method for producing petroleum pitch by catalytic liquid-phase oxidative cracking of crude oil using heterogeneous metal complex catalysts is proposed. The process of petroleum pitch production is shown to undergo several stages, including homogenization of fuel oil and modifying additives; oxidative cracking of fuel oil during heating of homogenized fuel oil in a furnace; catalytic liquid-phase oxidative cracking of fuel oil with removal of distillates; rectification of light fractions; condensation of distillates; collection of light oil products; oxidation of bottom residues by air and steam; removal of oxidation distillates and petroleum pitch; and pitch pelletizing. According to the conducted comparison of the as-obtained petroleum pitch with the B-1 coal tar pitch produced by the Altai Koks JSC, the proposed material meets the technological requirements of the Krasnoyarsk Aluminum Plant of the RUSAL company. In terms of sulfur content, the proposed petroleum pitch is superior to coal tar pitch. The experiments conducted at an aluminum plant showed the petroleum pitch to contain no harmful polyaromatic hydrocarbons, in particular, carcinogenic benz(a)pyrene. Therefore, replacement of coal tar pitch with petroleum pitch could provide technological and environmental advantages for primary aluminum producers, as well as for enterprises producing various carbon materials.

Electrolytic production of aluminium as a case study for linking engineering and fundamental concepts in industrial electrochemistry

Electrolytic production of aluminium as a case study for linking engineering and fundamental concepts in industrial electrochemistry

Molecular Dynamics Simulation of the Effect of Zr, B, C, W, Ti, Hf, Nb, and Ta Elements on the K3AlF6-Na3AlF6-AlF3 Molten Salt System

The criticality of the physicochemical properties of the K3AlF6-Na3AlF6-AlF3 molten salt system to electrolytic aluminum production is a topic of great interest. In this study, molecular dynamics simulations were conducted to investigate the impact of Zr, B, C, W, Ti, Hf, Nb, and Ta on various properties including the radial distribution function, coordination number, viscosity, and conductivity of the 23.4K3AlF6-54.6Na3AlF6-22AlF3 molten salt electrolyte under conditions of 1173 K and standard atmospheric pressure. Significant and noteworthy discoveries were yielded by the simulations. A decrease in the coordination between Al-F and conductivity was brought about by the inclusion of B2-. Likewise, higher Zr4+ content resulted in a decrease in the coordination number between Al-F and viscosity. The impact of carbon was insignificant, while the presence of tungsten reduced the coordination number between Al-F. On the other hand, titanium, hafnium, niobium, and tantalum facilitated the decomposition of Al-F ligands, leading to an increased coordination between Al-F and the ions in the electrolyte. These findings provide valuable insights for future investigations on inert anodes containing Zr, B, Ti, Hf, Nb, and Ta. By understanding the effects of these elements on the physicochemical properties of the molten salt electrolyte, this work lays a solid foundation for further research in the field.

Mineralogy and Geochemical Characteristics of Matamba Kaolin Deposit-Njombe Region South-Western Tanzania: Implications for Industrial Applications

Kaolin is a commercial clay material composed of hydrated aluminosilicate mineral kaolinite and used in various industrial applications such as ceramics, paper, paints, refractories, fiberglass, plastics, cosmetics and pharmaceuticals. It is formed as a result of strong chemical weathering of crystalline and feldspar-rich rocks or hydrothermal alteration of granitic rocks at relatively low temperature and pressure conditions. The kaolin deposit of Matamba originated from the weathering of leucogabbro rock during the development of the African land surface. In view of highlighted properties, the mineralogy and chemical characteristics of the Matamba kaolin deposit were investigated to determine its industrial applications. As part of the study approach, forty-six (46) samples were collected and analyzed for major oxides using X-ray fluorescence (XRF) and mineralogical composition using X-ray diffraction (XRD). The XRD results indicated that the Matamba kaolin is dominantly composed of kaolinite (10.1–100%) with other phases such as albite (1.2–56.8%), oligoclase (10.1–54.3%), quartz (1.2–33.9%), goethite (1.0–9.4%) and muscovite (1.1–29.5%). The dominant major oxides are SiO2 (39.78–67.96 wt.%), Al2O3 (14.60–38.07 wt.%) and subordinate amounts of Fe2O3 (0.93–6.37 wt.%), MgO (1.42–4.74 wt.%), Na2O (0.10–1.09 wt.%), K2O (0.14–2.01 wt.%), CaO (0.08–0.99 wt.%), TiO2 (0.07–1.66 wt.%), P2O5 (0.36–1.77 wt.%) and LOI (1.91–13.97 wt.%). These major oxides correlate with the mineralogical composition supporting kaolinite dominance. Consequently, compared with some industrial specifications, these results indicate that Matamba kaolin deposit may be useful for ceramic products, refractories such as fireclay crucibles and electrolytic production of aluminium and its alloys. However, it should be beneficiated and upgraded to improve some technical properties to qualify for other industrial applications.

ИССЛЕДОВАНИЕ МИНЕРАЛИЗУЮЩЕГО ЭФФЕКТА КРИОЛИТА И ЕГО ВЛИЯНИЯ НА ПРОЦЕССЫ КЛИНКЕРООБРАЗОВАНИЯ

The article discusses the possibility of using cryolite Na3AlF6, the main fluorine-containing compound of a man-made product of electrolytic aluminum production, as a mineralizing additive when burning clinker. A comparative assessment of the effectiveness of cryolite Na3AlF6, as a mineralizer, and calcium fluoride CaF2, a substance that has the most effective mineralizing effect, is provided. The influence of mineralizer additives on the processes of dissociation of calcium carbonate, assimilation of free calcium oxide with the formation of silicates, aluminates and calcium ferrites, liquid-phase sintering and clinker formation with the synthesis of basic clinker minerals is considered. The physical and chemical processes that occur when heating raw material mixtures without additives and with the addition of mineralizers – CaF2 and Na3AlF6 – to a clinker sintering temperature of 1450ºC are examined in detail. The dynamics of changes in the qualitative phase composition of firing products at various temperatures, ranging from 700ºC to the clinker sintering temperature of 1450ºC, as well as a quantitative characteristic of the intensity of formation of the main clinker minerals are presented. It has been determined that cryolite has a mineralizing effect and can be used as a mineralizer when burning clinker. The effectiveness of cryolite is comparable to the effectiveness of calcium fluoride, and the burning temperature of clinker can be reduced to 1400ºC

Effect of Nanopillars on the Wetting State and Adhesion Characteristics of Molten Aluminum Droplets.

To solve the adhesion problem between molten aluminum and vacuum ladle liner during the electrolytic aluminum production process, the wetting state and adhesion properties of molten aluminum droplets on substrate surfaces with different nanopillars are investigated based on molecular dynamics. The results show that the adhesion strength of molten aluminum droplets in different wetting states has the pattern Young state > Wenzel state > Cassie state. Effects of increasing nanopillar height or interval are poles apart in the wetting state and adhesion characteristics of aluminum molten droplets. The critical height and critical interval of the nanopillar where the wetting state transition occurs are obtained. The increase of the nanopillar width can induce the wetting state transition from the Cassie state to the Wenzel state. In addition, the phantom wall method is applied to study the variation of the separation force. It is found that a peak in the separation force curve occurs when the molten droplet separates from the bottom of the nanopillar interval or the top of the nanopillar. The separation force curves of the droplets in the Young state and the Cassie state have single peaks, while the droplets in the Wenzel state have double peaks.

A Risk Characterization Model and Visualization System in Aluminum Production

Electrolytic aluminum operation accidents have caused great losses to countries and people. Therefore, taking two typical accidents of explosion and leakage in electrolytic aluminum production as the research object, the form of accident risk characterization was explored and a risk characterization visualization system was designed. Based on the methods of risk assessment and characterization, the likelihood and consequence of accidents were studied. The influencing factors of likelihood and a type of Euclidean distance formula were used to characterize the likelihood. The consequence portion was characterized by two components, with one being the failure degree determined by the accident and the other being the exposure degree of people and equipment. The intensity of event was used to characterize the failure degree and the spatial search model was used to characterize the exposure degree. Finally, the visual system of electrolytic aluminum operation accidents was established based on the risk characterization model.

Temperature prediction of aluminum reduction cell based on integration of dual attention LSTM for non-stationary sub-sequence and ARMA for stationary sub-sequences

In aluminum electrolysis process, cell temperature is an important index to reflect the current efficiency of electrolytic cell. Maintaining cell temperature in an appropriate range can improve current efficiency and economic benefits. Because aluminum electrolysis process is in a complex environment with high temperature, strong corrosivity, multivariable coupling and nonlinearity, cell temperature measuring instrument and equipment have the shortcomings of short service life and high cost. Therefore, this paper develops a cell temperature prediction model based on the integration of dual attention long short-term memory (DA-LSTM) and autoregressive moving average (ARMA). Firstly, the cell temperature series is decomposed into non-stationary sub-sequence and stationary sub-sequences by wavelet transform. The DA-LSTM is proposed to approximate non-stationary sub-sequence, which introduces a two-stage attention mechanism including feature attention mechanism and temporal attention mechanism. ARMA is employed to predict the stationary sub-sequences. Then, the integration model for the cell temperature prediction is reconstructed through multiple linear regression of DA-LSTM and ARMA. The integration model can overcome the problems that the prediction accuracy of a single model is low and the hysteresis phenomenon due to the mixed multi-information of aluminum electrolysis time series data. Experiments in a real-world aluminum electrolysis production process are conducted to demonstrate the effectiveness of the proposed model.

Modern Compositions of Cast Iron Used for Pouring Anodes of Aluminum Electrolyzers

The purpose of this work is to review modern foreign experience to investigate cast iron used in the installation of anodes for aluminum electrolysis production at JSC «Kazakhstan Aluminium Smelter». In the course of the study, the chemical composition of cast iron was analyzed and the selection of experimental cast iron compositions was carried out. The research revealed that one of the causes of the problem of incomplete removal of cast iron from steel nipples of anode holders after the dismantling of cinders and high voltage drop in the contact nipple – anode is the chemical composition of cast iron. The requirements for cast iron for casting anodes have been determined. It is established that to achieve positive results it is recommended to use cast iron of stable composition with low crystallization shrinkage and low phosphorus content; increased fluidity

Material innovation and performance optimization of multi-solid waste-based composite grouting materials for semi-flexible pavements

With the increasing power generation capacity of circulating fluidized bed boilers and electrolytic aluminum production worldwide, the emissions of fluidized bed coal combustion fly ash (FBCF) and bayer red mud (BRM) have increased dramatically, resulting in extremely severe environmental issues as it is difficult to utilize these as resources. To address this issue, this study uses industrial solid wastes such as BRM, FBCF, and silica fume as mineral admixtures to develop a green and low-carbon early strength multi-solid waste composite grouting material (ESMSWCGM) for semi-flexible pavements (SFPs). According to the findings of this study, 18 % of the cement in the ESMSWCGM could be replaced with the three solid waste mineral admixtures. With the optimal ratio, the developed ESMSWCGM exhibits initial and 20-min flow-cone fluidities of 12 s and 14 s, respectively, and initial and final setting times of 66 min and 69 min, respectively. The compressive strengths at 3 h, 1 d, 7 d, and 28 d are 17.05 MPa, 22.95 MPa, 29.55 MPa, and 30.72 MPa, respectively, and the dry shrinkage rate at 28 d is 0.12 %. The performance of the SFP material obtained through grouting is excellent. When the grouting saturation is 95 %, the SFP has a dynamic stability of 28911, a rutting depth of 1.19 mm, and a splitting strength of 1.91 MPa.

Recovery of carbon and cryolite from spent carbon anode slag of electrolytic aluminum by flotation based on the evaluation of selectivity index.

One of the main electrolytic aluminum production costs is the consumption of carbon anodes, and carbon anode slag is a common hazardous waste in the aluminum industry. In this work, electrolytic aluminum carbon anode slag was separated by flotation. Using the selectivity index (SI) as an indicator, the influencing factors of the carbon slag flotation process were optimized, and the separation performance of carbon and cryolite in the carbon anode slag was investigated. The raw carbon anode slag was ground for 40 min to achieve dissociation of the cryolite from the carbon, the optimized SI value was then used to determine the optimal flotation test conditions. The test results showed that the SI value under the optimal grinding flotation was approximately four times larger than the value of direct flotation. This indicated that carbon anode slag had a better flotation selectivity under the grinding flotation, which significantly improved the flotation performance.