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Article

A Novel Effective Arsenic Removal Technique for High-Arsenic Copper Minerals: Two-Stage Filtration Technology Based on Fe-25Al Porous Material

by
Xiaowei Tang
1,2,* and
Yuehui He
2,*
1
Materials Science and Engineering, Changsha University of Science & Technology, Changsha 410114, China
2
State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
*
Authors to whom correspondence should be addressed.
Appl. Sci. 2025, 15(16), 8899; https://doi.org/10.3390/app15168899
Submission received: 9 July 2025 / Revised: 30 July 2025 / Accepted: 8 August 2025 / Published: 12 August 2025
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Abstract

Effective arsenic removal is a challenge when smelting high-arsenic copper minerals (HACMs, As > 3.0 wt%). Current arsenic-removal methods for HACM smelting cannot effectively remove arsenic and do not satisfy environmental requirements. This study argues that two-stage filtration based on Fe-25Al porous material and oxygen-controlled roasting is an effective technique for HACM arsenic removal (As = 11.8 wt%). The use of two-stage filtration facilitated double interception: particles larger than 10 μm were mechanically intercepted by the pore channels, and submicron particles (0.1–10 μm) were intercepted by the filter cake. Specifically, in the second stage, the flue gas underwent gradient rapid cooling, and the arsenic in the flue gas rapidly condensed, resulting in efficient arsenic removal. The purity of the condensed product, As2O3, was greater than 99%. Moreover, adding sand to the roasted mineral increased the specific surface area from 0.484 m2/g to 0.590 m2/g, reducing the “bottleneck effect” of pores; the addition of carbon further increased the surface area to 2.457 m2/g, inhibiting the formation of arsenate. When the mineral feed rate increased from 50 kg/h to 80 kg/h, the oxygen partial pressure decreased; this effectively inhibited the formation of iron arsenate, and the arsenic removal efficiency increased from 70.20% to 95.61%. The optimized process achieved ≥94% arsenic removal efficiency and ≥76% sulfur-fixation efficiency, with low energy cost. Material balance analysis showed that after arsenic removal, the Cu/Si to Fe/Si ratio of the copper mineral reached 1.5, which is appropriate for immediate subsequent smelting. This study provides a new technological strategy for HACM arsenic removal.

1. Introduction

There has been a notable decline in high-grade and beneficial copper reserves, impacting copper resources. Global reports indicate a decrease in the average grade of copper mineral from 1.6% in 1990 to approximately 1% at present [1,2,3]. As high-quality copper ore resources have diminished, high-arsenic copper minerals (HACMs) have been extensively applied in the copper metallurgical industry [4,5,6]. Generally, copper minerals with an arsenic content exceeding 3.0% are classified as HACMs and cannot directly enter the smelting system [7]. HACM smelting processes generate various harmful substances, among which arsenic is a common and significantly hazardous compound [8]. Arsenic is toxic to the human body, causing acute poisoning upon short-term exposure and potentially leading to cancer with prolonged contact [9,10]. This highly toxic and volatile element poses a triple hazard to metallurgical processes. Firstly, in the 1200–1300 °C smelting process, the arsenic volatilization rate can reach 60–80% and cause a decrease in the purity of metal products [11]; secondly, the volatile arsenic trioxide reacts with the furnace lining to form low-melting point compounds, resulting in a 30–40% reduction in equipment lifespan [12]; thirdly, the proportion of gas-phase arsenic in smelting flue gas reaches 45–65%, from which highly toxic arsenic trioxide diffuses through the atmosphere, causing arsenic enrichment in the surrounding soil at levels exceeding 40 mg/kg [13].
At present, traditional methods for arsenic removal in metal smelting mainly include wet and pyrometallurgical arsenic removal, which do not meet environmental policy standards [14,15,16,17,18,19,20]. Wet arsenic removal usually removes arsenic from smelting waste gas through chemical absorption, precipitation, and other methods. The most used chemical adsorbents include sodium hydroxide, ammonia water, NaClO oxidization, etc. [21,22,23,24,25]. However, the disadvantages of this method are its complex operation, low efficiency, accompanying frequent generation of large volumes of wastewater, high treatment costs, and high potential to corrode equipment [23]. The pyrometallurgical method converts arsenic into gas through high-temperature incineration and effectively recovers arsenic from factory flue gas produced after condensation [26,27,28,29]. However, pyrometallurgical arsenic removal involves high energy consumption and serious environmental pollution [30], especially when treating high-temperature flue gas, which is a challenging problem. This type of method usually produces a large quantity of harmful gases, such as sulfur dioxide, during the arsenic removal process, polluting the environment [31]. In addition, slurry electrolysis [32], magnetic biochar adsorbent [33], and surface complexation model [34,35] may innovatively be used in arsenic removal technology in the future, and ultrasonic may enhance arsenic-removal efficiency [36]. Developing an effective arsenic removal method characterized by high efficiency, streamlined integration, cost-effectiveness, and environmental sustainability remains imperative for advancing pollution control in the non-ferrous metallurgical sector.
Fe-25Al porous material demonstrates high temperature, oxidation, and sulfur resistance [37,38,39], making it particularly suitable for filtering flue gas in metal smelting [38,39]. To overcome the shortcomings of traditional arsenic-removal methods in metal smelting, this study proposes a novel arsenic removal strategy: two-stage filtration combined with controlled-oxygen roasting. Based on gradient-temperature control and Fe-25Al porous material filtration [40,41,42,43], the two-stage filtration process was designed and tested as follows: The first stage in the high-temperature section (500~600 °C) uses the Fe-25Al porous matrix slit effect to intercept arsenic-containing flue particles larger than 10 μm, while the second stage in the low-temperature section (200~300 °C) condenses gaseous As2O3 through quenching. This scheme simplifies the process, reduces energy consumption, and increases environmental friendliness through a synergistic mechanism of structural filtering and phase change capture. It is capable of recovering an As2O3 condensate with purity greater than 99% for arsenic resource regeneration. In addition, the conditions for the effective filtration of Fe-25Al porous materials were investigated, and the limiting conditions for subsequent mineral arsenic removal were clarified, providing an experimental and theoretical basis for the industrial application of Fe-25Al porous materials in mineral arsenic removal.

2. Materials and Methods

2.1. Arsenic-Bearing Copper Mineral

The arsenic-bearing copper mineral used in this study was provided by the CHINALCO (Aluminum Corporation of China Ltd., Beijing, China) [39]. The chemical compositions of this copper mineral are shown in Table 1, and its arsenic content is 11.8 wt%, classifying it as an HACM.
The mineralogical composition of the arsenic-bearing copper mineral mainly included chalcopyrite, chalcopyrite, pyrite, and arsenopyrite (Table 2). Among them, chalcopyrite, chalcopyrite, and arsenopyrite (arsenopyrite) are the main sources of arsenic [19].

2.2. Fe-25Al Porous Material Preparation

Fe-25Al porous material was synthesized as described in previous reports [38]. Briefly, Fe and Al raw material powders were weighed according to the process ratio and loaded into a V-shaped mixer. The material powders were mixed for 24 h to ensure complete and even mixing. Ordinary film pressing was used to press the metal mixture, at 110 MPa, and the sample was pressed into a block shape measuring 40 mm × 10 mm × 3 mm. The Fe and Al mixture was vacuum sintered. First, the mixture was heated to and maintained at 120 °C for 0.5 h to fully remove the moisture; then, the gas in the mixture was completely adsorbed. Secondly, the temperature was raised to 600 °C at a rate of 5 °C/min and maintained for 1 h to allow the reaction between Fe and Al to fully proceed. Then, the temperature was raised to 1200 °C at a rate of 5 °C/min and kept for 2 h to ensure uniform diffusion of the sample components; thus, Fe-25Al porous material with good structure and properties was produced. Finally, the Fe-25Al porous material was slowly cooled to room temperature. The open porosity, average pore size, and gas permeability of the Fe-25Al porous material were determined to be 42.0%, 18.3 μm, and 260/m3h−1kPa−1m−2, respectively.

2.3. Thermogravimetric Differential Thermal Analysis

Thermogravimetric differential thermal analysis (WATERS Co., Ltd., Milford, CT, USA) combined with X-ray diffraction (PA Nalytical Co., Ltd., Almelo, The Netherlands) was used to analyze the roasting behavior of the arsenic-bearing copper mineral in an air atmosphere, clarify its phase-transition rules at different temperature stages, and infer its reaction mechanism [44]. During arsenic-removal experiments with roasting, the sample was first subjected to TG-DTA analysis in an air atmosphere. Here, due to the high sulfur content of the arsenic-bearing copper mineral, direct detection of TG-DTA was not possible, and it was necessary to add nine times the mass of Al2O3 for dilution.

2.4. Experimental Conditions

The experimental conditions were as follows: calcination temperature of 700 °C, time of 30 min, oxygen content of 4 vol%, and gas flow rate of 0.8 L/min. Under these conditions, the arsenic removal efficiency was significantly improved, and the residual arsenic content was reduced to 0.39 wt% [38,45].

2.5. Two-Stage Filtration with Gradient Temperature Control

The aim of two-stage filtration with gradient temperature control is to construct an arsenic separation system with a synergistic temperature structure [39,46]. The two-stage filtration system based on Fe-25Al porous material adopted a staged-phase change separation mechanism: the first stage was high-temperature filtration (600 ± 20 °C) to achieve gas–solid separation, and the second stage was low-temperature filtration (250 ± 10 °C) to complete the phase change capture of gaseous arsenic (as shown in Figure 1). The gas–solid separation efficiency of the system depended on the intrinsic pore structure of the porous matrix and the dynamically formed filter cake layer. To maintain the filtration flux, the system integrates a pulse blowback (frequency 2–3 times/min). The entire process consists of the following three subsystems.

2.5.1. First Filtration System

The first-filtration system separated arsenic and other particulate matter from flue gas at high temperatures. This system was responsible for the purification of high-temperature flue gas from metal smelting. When the smelting flue gas flowed through the Fe-25Al porous body, double interception occurred. Particles larger than 10 μm in the flue gas were mechanically intercepted by the pore channels, while a filter cake intercepted submicron particles between 0.1 and 10 μm (Figure 2). The core technology of the initial filtration step is the porous material. The Fe-25Al porous material is one of the best optimum alloy materials [47], with excellent high-temperature resistance and strong chemical stability [48]. It can effectively capture and collect mineral dust in flue gas from metal smelting. Meanwhile, arsenic is oxidized into arsenic oxide during filtration at high temperature. Optimizing the first filtration system can improve the separation efficiency of flue gas and reduce secondary pollution.

2.5.2. Secondary Filtration System

After the first filtration, the main residual components in the flue gas were arsenic and other gases such as SO2 (g). Therefore, it was necessary to extract arsenic from the flue gas through secondary filtration. Despite undergoing rapid gradient cooling at this stage, the arsenic in the flue gas was rapidly condensed. The gaseous arsenic underwent three stages: supersaturation condensation, particle growth, and deep capture [48]. A rapid transition from As4O6 (g) to As2O3 (S) occurred [47]. To achieve efficient arsenic removal in the second filtration step, it was necessary to control the temperature, flue gas flow rate, and porosity of the filtration membrane (Figure 3). The final condensed product, As2O3 (s), had over 99% purity. The dual goals of efficient arsenic removal and resource utilization were achieved using a secondary filtration system [48].

2.5.3. Blowback Regeneration System

During the first and second filtration processes, arsenic and particulate matter gradually accumulated on the surface of the filtration materials in each system, leading to a decrease in filtration efficiency. To counteract this, a blowback regeneration system was designed to decrease the accumulation of arsenic and particulate matter by periodically blowing high-pressure nitrogen gas into the filter material to remove dust and arsenic particles on the filter surface, thereby restoring its permeability (Figure 4). In the blowback regeneration system, there are two filtration stages. The first filtration stage filtrated more dust and had a higher blowback frequency; and the second filtration stage had a lower blowback frequency. Implementing this, the blowback regeneration system can extent the service life of the filter, and reduce operating costs. In industrial practice, this blowback system can not only improve filtration efficiency but also significantly reduce the frequency of equipment replacement.

2.6. Process Flow and Equipment Structure

The pilot test was conducted in a rotary furnace, and the schematic diagram of the complete equipment is shown in Figure 5 and Equipment Structure Diagram is shown in Figure 6. Copper concentrate is loaded into a rotary furnace driven by an electric motor. The rotary furnace has a certain inclination angle, and, during the rotation process, minerals gradually flow from the inlet to the outlet. After heating and decomposition, arsenic containing dust and arsenic-free copper concentrate are generated. The equipment, as a whole, is in a negative pressure state drawn by the filter, and the flue gas flows to the filter for high-temperature gas–solid separation. Under high temperature conditions, gaseous arsenic oxide enters the pipeline for cooling and condenses before entering the bag arsenic collection system. The heat generated during the decomposition process is provided by the combustion diesel flue gas in the combustion chamber, which heats the outer wall of the rotary furnace to increase the temperature. The roasting equipment is provided by Tianyuan (Tianyuan Machinery Equipment Technology Co., Ltd., Guangzhou, China) and the FeAl porous membrane in the filter is provided by Yitai (Yitai Technology Co., Ltd., Chengdu, China).

2.7. Preliminary Experiments

The main operating parameters of the preliminary test were designed as follows [38]: the raw material was copper concentrate; the additive was sand, and the ingredient ratio was 20%, which prevented any blockage caused by the high moisture content of the material. The feed rate was 180 kg/h; the total amount of feed was 550 kg; the temperature (TT05) was 590~700 °C; the stay time was 150 min (10 Hz); the kiln pressure was—600 pa; the diesel fuel consumption was 100 L; the power consumption was 260 Kw/h; and the roasting temperature was TT05, similar to the jacket temperature between the inner and outer cylinders at the tail end of the rotary kiln.

2.8. Optimized Experiments

Twelve sets of calcination experiments were designed and conducted, optimizing various parameters of calcination. The main operating parameters of the optimization experiment are shown in Table 3.

2.9. Continuous Operation Experiment

Under optimal operating and process parameters, continuous operation experiments were conducted to verify the effect of arsenic removal and sulfur fixation on the pilot equipment. The main operating parameters are shown in Table 4.

3. Results and Discussion

3.1. TG-DTA Analysis of Arsenic-Bearing Copper Mineral Roasting

TG-DTA combined with XRD was used to analyze the roasting behavior of the arsenic-bearing copper mineral. The results showed that Al2O3 did not react throughout the entire heating stage; thus, it had no impact on the TG-DTA analysis. When the experiment was heated from room temperature to 1000 °C, the DTA of the samples exhibited temperature peaks at 95.72 °C and 497.49 °C, the boiling points of water and sulfur, respectively. The TG analysis of the samples showed four stages of weight change throughout the heating process. The change distribution showed a weight decrease of 0.494% from room temperature to 390 °C, a weight decrease of 0.139% from 390 °C to 480 °C, a weight increase of 0.276% from 480 °C to 610 °C, and, finally, a weight decrease of 0.903% from 610 °C to 780 °C.

3.2. Preliminary Experiment Analysis

The samples used for the preliminary experiments were derived from roasted copper minerals after arsenic removal with controlled oxygen roasting. Roasting minerals were taken from the middle section of the roasting furnace discharge process, excluding copper minerals that were discharged from the furnace and final test condition. All samples underwent 80-mesh screening to remove sand and prevent it from affecting the test results. As shown in Table 5, under the initial test conditions, the arsenic content of the copper minerals after arsenic was removed decreased from 10.94% to 1.07%, and the sulfur content of the copper concentrate was 23.17%. The experimental results agreed with the expected target results, providing reliable technical support for subsequent parameter optimization experiments.

3.3. Optimization Experiment Analysis

After arsenic removal and sulfur fixation data were obtained in the preliminary experiments, further optimization experiments were conducted to explore the optimal operating and processing parameters suitable for the pilot equipment. To ensure the sulfur fixation, the residual arsenic in the roasted copper mineral was further reduced to achieve the best arsenic removal results. Sampling for the analyses of the optimization experiments should be derived from the middle section of the roasted copper minerals. The samples from the initial and final stages of production were excluded. All the samples underwent 80-mesh screening to remove sand and carbon black, and prevent them from affecting the test results. The results are shown in Table 6.
The optimized experiment was divided into three stages based on the experimental objectives. The first stage (1–2) involved adjusting the equipment temperature to above 700 °C in the early stage of the experiments. In this stage, reducing the feed rate was beneficial for arsenic removal. In the second stage (3–7), the feed rate was reduced to 50 kg/h, and the decrease in the feed rate increased the oxygen content in the roasting furnace, resulting in the information of non-volatile substance substances, such as iron arsenate. Other adjustments to the process were also ineffective. In the third stage (8–10), the first step increased the feed rate to 100 kg/h, and the second step gradually decreased the feed rate. When the feed rate was adjusted to 80 kg/h, the residual arsenic dropped to 0.48 wt%, meeting the national import standards. The experimental results indicate that the oxygen in the roasting process can be indirectly controlled by adjusting the feed rate.

3.4. Continuous Operation Experiment Analysis

Based on data from parameter optimization experiments, continuous operation experiments were conducted to verify the arsenic removal and sulfur fixation effects using pilot equipment. The equipment was used in continuous feeding operations under optimal operating and processing parameters. The motor frequency was 10 Hz, and the roasted copper concentrate was sampled at different time points and analyzed after arsenic removal. The samples were derived from the roasted concentrate at the middle stage of the oxygen-controlled roasting furnace discharge process. The samples from the initial and final stages of removal from the furnace were excluded. All the samples underwent 80-mesh screening to remove sand and carbon black to avoid any impact on the detection results. The results are shown in Table 7. The parameters for the arsenic removal and sulfur fixation of the continuous operation experiment achieved the purpose of continuous operation testing.

3.5. Arsenic Removal Effect of Fe-25Al Porous Material on HACM Smelting

The sampling and analysis conducted on various components in the parameter optimization experiment are depicted in Figure 7. Figure 7A illustrates the dust sampling locations during the filtration process of Fe-25Al material, encompassing samples collected from the discharge outlet, pipeline, filter residue outlet, and outlet of filtered gas. Figure 7B presents the XRD analysis results of the primary components of HACM before and after calcination, revealing that Cu3AsS3 has vanished and transformed into CuFeS2 within the HACM post-calcination. Figure 7C displays the dust collected from both the pipeline and filter residue outlet. The results indicate a similarity in material structure between the two locations; however, the diffraction peak intensity of As2O3 is more pronounced at the filter residue outlet. This is attributed to the lower temperature at the filter residue outlet compared to the pipeline, leading to enhanced condensation of As2O3 at the former. Lastly, Figure 7D showcases the dust after filtration. Upon comparison with the standard card for As2O3, it is evident that the condensed powder consists of high-purity As2O3, with an arsenic oxide content reaching 99.17 wt%, making it suitable for direct use in subsequent arsenic metal smelting processes.

3.6. Roasted Mineral Balance and Energy Consumption Analysis

The continuous operation experiment results and detection data were extracted, and the material balance of the copper concentrate after arsenic removal is shown in Figure 8. After arsenic removal, the copper content significantly increased to 28.00 wt%, the arsenic residue decreased to 0.80 wt%, and the sulfur content remained at a high level of 22.00 wt%, which is beneficial for subsequent smelting and meets the design expectations. In the continuous operation experiment, sand was added at 15%, and the Cu/Si and Fe/Si amounts of the arsenic-removed mineral powder were about 1.5, which meets the requirements for subsequent smelting.
In addition, the energy consumption of the continuous operation experiments was analyzed, with the results shown in Table 8. Energy consumption data for continuous operation are relatively stable. In the case of a small volume, the fluctuations in the mineral amount did not have a significant impact on energy consumption. The energy consumption cost for processing approximately 500 kg is about CNY 500 (≈70 × 5 + 210 × 0.8).

3.7. Equipment and Running Costs

The estimated project investment is 30.655 million CNY, mainly including equipment investment and simple factory buildings, excluding site costs, three connections and one leveling, and civil engineering projects such as public facilities, as shown in Table 9 below.
If the cost of raw ore procurement is not considered, the total annual operating cost of this project is 40.1481 million yuan, with a unit operating cost of 401.48 CNY per ton and a total cost of 511.78 CNY per ton., as shown in Table 10 below.
The gas consumption was estimated based on the energy balance calculation results and the actual production of similar projects in Xinjiang. The electricity bill was calculated based on the installed power, of which the electricity required for the As2O3 reaction accounted for about 30%. According to market transaction prices, the arsenic residue in copper concentrate was reduced from over 10 wt% to below 1 wt%, resulting in an increase in copper concentrate value with approximately 1000–1200 yuan/ton. The gross profit margin of this project, if being calculated at 70%, was approximately 25%, with no revenue from arsenic containing products. In the above cost analysis, the processing fee for metal arsenic was about 15 million yuan/year. If the yield of refined arsenic was calculated at 10%, the unit processing fee was about 1500 yuan/ton, which was about 50% of the processing fee for this type of chemical industry in Chenzhou. The reason is that an intermittent furnace is used, and the energy consumption for heating and cooling each furnace is very high. Only small-scale experimental production was conducted, and the relevant data statistics were insufficient.
The performances of Fe-25Al two-stage filtration combined with controlled oxygen roasting, traditional wet arsenic removal, and traditional pyrometallurgical arsenic removal were summarized, and the results are shown in Table 11.

4. Conclusions

We conducted optimization experiments on two-stage filtration based on Fe-25Al porous material connected with oxygen-controlled roasting for arsenic-bearing copper minerals, pilot experiments, and an evaluation of the filtration effect of Fe-25Al material. We obtained the following findings: (1) In two-stage filtration processes, the smelting flue gas flows through the Fe-25Al porous body and undergoes double interception, where particles larger than 10 μ m are mechanically intercepted by the pore channels, and submicron particles (0.1–10 μ m) are intercepted by the filter cake at the first filtration. In the secondary filtration stage, the flue gas undergoes rapid gradient cooling, and the arsenic in the flue gas is quickly condensed. The gaseous arsenic undergoes supersaturation condensation, particle growth, and deep capture, and is efficiently removed. The purity of the condensed product As2O3 (s) is greater than 99%. (2) Adding sand (SiO2) and carbon black (C) to the roasted mineral significantly improves the pore structure of the roasted mineral and increases the specific surface area from 0.484 m2/g to 0.590 m2/g, reducing the “bottleneck effect” from pores. The addition of carbon black further increases the specific surface area to 2.457 m2/g and indirectly reduces local oxygen partial pressure through carbon–oxygen reactions, inhibiting the formation of arsenate. Adding 10 wt% carbon black can reduce the residual arsenic to 0.48 wt%. (3) The oxygen content in the roasting furnace can be indirectly controlled by adjusting the mineral feed rate. When the feed rate is increased from 50 kg/h to 80 kg/h, the oxygen partial pressure decreases, which effectively inhibits iron arsenate formation, and the efficiency of arsenic removal increases from 70.20% to 95.61%. Under optimized conditions (80 kg/h feed rate, 700~740 °C roasting, and 10 wt% carbon black), the residual arsenic in the roasted mineral was steadily reduced to 0.48 wt%, and the sulfur retention rate reached 70.22%, fully meeting the requirements for arsenic removal and sulfur fixation. (4) The optimized process can stably achieve an arsenic removal efficiency ≥ 94% and a sulfur-fixation efficiency ≥ 76%, and the energy cost is controllable (500 kg of material costs is about CNY 500). The material balance analysis showed that the Cu/Si to Fe/Si ratio of the roasted copper mineral reaches 1.5, indicating that it can be directly used for subsequent smelting. (5) The Fe-25Al porous material can efficiently capture As4O6 (with a condensed powder arsenic content of 99.17 wt%), but its filtration efficiency for As4S4 is relatively low. In this study, we propose a combination strategy of oxygen and temperature control (by maintaining a gas–solid separation temperature of ≥550 °C) with an oxygen partial pressure of ≥2.026 kPa to optimize the transformation of arsenic forms, resolving the issue of As2O3 blockage through the blowback frequency. This provides a new technological strategy for the purification of arsenic-containing gases at high temperatures.

Author Contributions

All authors contributed to the study conception and design. The material preparation, data collection, and analysis were performed by X.T., Y.H. supervised the project. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data is contained within the article.

Acknowledgments

We appreciate the contribution of the various members in Yuehui He’s Laboratory of the Powder Metallurgy Research Institute and the State Key Laboratory of Powder Metallurgy, Central South University.

Conflicts of Interest

The authors declare no conflicts of interest.

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Applsci 15 08899 g001
Figure 1. Model diagram of two-stage filtration system.
Figure 1. Model diagram of two-stage filtration system.
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Figure 2. First-stage filtration model.
Figure 2. First-stage filtration model.
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Figure 3. Second-stage filtration model.
Figure 3. Second-stage filtration model.
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Figure 4. Pulse-jet cleaning regeneration unit.
Figure 4. Pulse-jet cleaning regeneration unit.
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Figure 5. Flowchart of two-stage filtration and roasting process.
Figure 5. Flowchart of two-stage filtration and roasting process.
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Figure 6. Equipment Structure Diagram of two-stage filtration and roasting process.
Figure 6. Equipment Structure Diagram of two-stage filtration and roasting process.
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Figure 7. Analysis on the filtrated products by Fe-25Al porous material. Output route of the products (A); XRD pattern of the raw mineral and products (B), concentrate (a) and roasted concentrate (b); XRD pattern of pipeline dust and filter residue (C), pipeline dust (c) and filter residue (d); XRD pattern of the condensation powder and standard card of As2O3 (D), condensation powder (e).
Figure 7. Analysis on the filtrated products by Fe-25Al porous material. Output route of the products (A); XRD pattern of the raw mineral and products (B), concentrate (a) and roasted concentrate (b); XRD pattern of pipeline dust and filter residue (C), pipeline dust (c) and filter residue (d); XRD pattern of the condensation powder and standard card of As2O3 (D), condensation powder (e).
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Figure 8. Material balance for arsenic removal from copper concentrate.
Figure 8. Material balance for arsenic removal from copper concentrate.
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Table 1. Chemical composition of arsenic-bearing copper mineral.
Table 1. Chemical composition of arsenic-bearing copper mineral.
ElementCuFeSAsBiSbZn
wt%23.223.434.811.80.220.891.27
Table 2. Mineralogical composition of arsenic-bearing copper concentrate.
Table 2. Mineralogical composition of arsenic-bearing copper concentrate.
MineralEnargite
(Cu3AsS4)		Tennantite
(Cu12As4S13)		Chalcopyrite
(CuFeS2)		Pyrite
(FeS2)		Arsenopyrite
(FeAsS)
wt%19.523.17.6427.415.6
Table 3. The main operating parameters of the optimization test.
Table 3. The main operating parameters of the optimization test.
NoSand (%)Charcoal (%)Feedrate (kg/h)Total Amount (kg)Temperature (℃)Time (min)Furnace Pressure (Pa)Air BlowNitrogen (MP)
1/100360660~71090−200Y/
2102200550690~740130−100N0.2
3102100330670~710150−200N0.2
4102100300700~740120−100N0.2
510350-750~7600−200Y0.25
610350-780~8000−100Y0.25
710350-760~8100−200Y0.25
810350-730~7600−100Y0.25
910350150700~750210−160Y0.2
10103100300700~740120−160Y0.2
11103120360700~740120−100Y0.2
1210380280700~740120−60Y0.2
Table 4. Continuous operation test of the main working condition parameters.
Table 4. Continuous operation test of the main working condition parameters.
NoSand (%)Charcoal (%)Feedrate (kg/h)Total Amount (kg)Temperature (°C)Furnace Pressure (Pa)
A103100300650~730−200
BA returned to the furnace100130700~730−100
C10390315700~730−200
DC returned to the furnace100170700~710−100
E10380320700~730−200
FE returned to the furnace80170660~700−100
G10390315730~760−200
HG returned to the furnace90135740~760−100
I10380200730~760−160
J15080200730~740−160
K5380260730~740−100
L5080200700~730−60
Table 5. Arsenic and sulfur content of raw copper minerals and arsenic removal minerals.
Table 5. Arsenic and sulfur content of raw copper minerals and arsenic removal minerals.
ElementsRaw Copper MineralArsenic Removal From Copper MineralArsenic Removal EfficiencySulfur Fixation Efficiency
As10.94%1.07%90.31%
S27.40%23.17% 84.56%
Table 6. Parameter optimization experiment test results.
Table 6. Parameter optimization experiment test results.
NoArsenic Content (wt%)Sulfur Content (wt%)Arsenic Removal Efficiency (%)Sulfur Fixation Efficiency (%)
10.9316.5512.2771.42
20.8321.7592.579.38
30.7816.7692.8761.68
40.7415.3993.2456.19
55.732.5747.629.38
64.142.0362.167.40
73.261.8170.206.61
82.971.4873.135.40
93.063.1672.0311.53
100.6024.7494.5190.29
110.6624.6293.9889.85
120.4819.2495.6170.22
Table 7. Continuous operation test results.
Table 7. Continuous operation test results.
NoArsenic Content (wt%)Sulfur Content (wt%)Arsenic Removal Efficiency (%)Sulfur Fixation Efficiency (%)
A1.6524.3984.9289.01
B0.8814.8291.9654.09
C1.4323.0686.9384.20
D0.6115.3894.4156.13
E0.9411.9791.4143.78
F0.8621.3692.1477.96
G1.2922.4988.2141.93
H0.5620.6894.8876.13
I0.4717.8695.7065.26
J0.8821.9491.9680.11
K1.2322.2288.7681.09
L1.0424.8490.4990.66
Table 8. Energy consumption of continuous operation experiments of copper mineral roasting.
Table 8. Energy consumption of continuous operation experiments of copper mineral roasting.
NoSand (%)Charcoal (%)Feedrate (kg/h)Total Amount (kg)Diesel Consumption (L)Electricity Consumption (kWh)
A10310030075190
BA returned to the furnace100130
C1039031560210
DC returned to the furnace100170
E1038032070210
FE returned to the furnace80170
G1039031560205
HG returned to the furnace90135
I1038020060215
J15080200
K538026075305
L5080200
Table 9. Investment estimation analysis of two-stage filtration-combined controlled-oxygen roasting.
Table 9. Investment estimation analysis of two-stage filtration-combined controlled-oxygen roasting.
No.ItemsCost (Million CNY)Notes
1Mixing and feeding/discharging device1.50
2Preheating furnace3.00
3Oxygen controlled roasting furnace5.60
4High temperature filter3.20
5Combustion and heating system1.80
6Reduction furnace2.00Alternative
7Condensation arsenic collection device1.80
8Tail gas purification device2.00
9Auxiliary equipment2.00Air compressor and nitrogen generator
10Electrical and Instrumentation System1.80
11Installation and debugging fees3.7015% of all equipment costs in the front
12Simple factory building2.25
Total project investment30.65
Table 10. Cost analysis of two-stage filtration-combined controlled-oxygen roasting per year.
Table 10. Cost analysis of two-stage filtration-combined controlled-oxygen roasting per year.
No.ItemsCost (Million CNY)Notes
1Gas 12.00Gas consumption 40 m3/t, price 3.0 CNY/m3
2Electricity6.22Total power 1800 kw, price 0.6 CNY/kw·h
3Water0.90Water fee, 6 CNY/t
4Texturizer3.0010 k tons per year, 300 CNY/ t
5Carbon9.5025 kg carbon per year, price 3.8 CNY/kg
6Pharmaceutical2.00Chemicals consumed per ton of material 20 CNY
7Labor6.0060 people, 100 k CNY/person/year
8Equipment maintenance fee0.86Calculated at 3.5% of the total equipment cost
9Management expense2.025% of the sum of 1–8 expenses
Annual total operating cost42.50
Unit operating cost per tons425.10Annual processing of 100 k tons
Depreciation and amortization per tons61.315-year comprehensive depreciation
Tax per tons42.006% of income
Total cost per tons528.41Processing cost of arsenic containing metal
Table 11. Performance comparison of traditional arsenic-removal methods with two-stage filtration.
Table 11. Performance comparison of traditional arsenic-removal methods with two-stage filtration.
ProcessPrincipleAdvantageDisadvantage
PyrometallurgicalUtilizing the volatile nature of arsenic to separate arsenic from metal compounds through roasting.Efficient, short process, and wide applicabilitySerious pollution of arsenic-bearing smoke and dust emissions
HydrometallurgicalUtilizing the different solubility characteristics of metals and arsenic to separate arsenic.Well arsenic removal effect, mild conditions, and low environmental riskHigh demands for pharmaceuticals and equipment, difficult treatment of waste liquids
BiologicalUsing arsenic-loving microorganisms, such as the genus Thiobacillus, to separate arsenic.Environmentally friendly, low-cost, suitable for low-grade mineralsLong cycle, poor adaptability of bacterial strains, and difficulty in industrialization
Two-stage filtrationUsing Fe-25Al porous material filtration based on pyrometallurgical method to separate arsenicEfficient, short process, wide applicability, environmentally friendlyProcess complex
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Tang, X.; He, Y. A Novel Effective Arsenic Removal Technique for High-Arsenic Copper Minerals: Two-Stage Filtration Technology Based on Fe-25Al Porous Material. Appl. Sci. 2025, 15, 8899. https://doi.org/10.3390/app15168899

AMA Style

Tang X, He Y. A Novel Effective Arsenic Removal Technique for High-Arsenic Copper Minerals: Two-Stage Filtration Technology Based on Fe-25Al Porous Material. Applied Sciences. 2025; 15(16):8899. https://doi.org/10.3390/app15168899

Chicago/Turabian Style

Tang, Xiaowei, and Yuehui He. 2025. "A Novel Effective Arsenic Removal Technique for High-Arsenic Copper Minerals: Two-Stage Filtration Technology Based on Fe-25Al Porous Material" Applied Sciences 15, no. 16: 8899. https://doi.org/10.3390/app15168899

APA Style

Tang, X., & He, Y. (2025). A Novel Effective Arsenic Removal Technique for High-Arsenic Copper Minerals: Two-Stage Filtration Technology Based on Fe-25Al Porous Material. Applied Sciences, 15(16), 8899. https://doi.org/10.3390/app15168899

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