Automated roaster feed system

Abstract

The current invention is directed to an automated roaster feed system, comprising a rotary table feeder equipped with at least one height-adjustable scraper for split- ting an incoming material stream into two outgoing material streams, at least one pair of slinger belt feeders for receiving the outgoing material streams from the rotary table feeder, each equipped with vibration and temperature sensors, at least one feed gate valve associated with the slinger belt feeders, configured to automatically close when a corresponding slinger belt feeder fails or stops and at least one automatic lifting device for the at least one scraper, enabling the auto- matic lifting and closing of discharge openings by gate valves upon failure or stop- page of an slinger belt feeders. Further, the invention also belongs to a process using the automated roaster feed system.

Description

[0001] Automated roaster feed system

[0002] The current invention is directed to an automated roaster feed system, comprising a rotary table feeder equipped with at least one height-adjustable scraper for splitting an incoming material stream into two outgoing material streams, at least one pair of slinger belt feeders for receiving the outgoing material streams from the rotary table feeder, each equipped with vibration and temperature sensors, at least one feed gate valve associated with the slinger belt feeders, configured to automatically close when a corresponding slinger belt feeder fails or stops and at least one automatic lifting device for the at least one scraper, enabling the automatic lifting and closing of discharge openings by gate valves upon failure or stoppage of an slinger belt feeders. Further, the invention also belongs to a process using the automated roaster feed system.

[0003] Roasting is a critical process in the metallurgical industry, particularly in the extraction and processing of metal ores. It involves the heating of ore in the presence of air to bring about a thermal reaction, which typically transforms the ore into an oxide or another chemical form suitable for further processing. This process is vital for the production of various metals, including gold, copper, and zinc, among others. Over the years, several roasting technologies have been developed, with fluidized bed systems emerging as one of the most efficient and widely used methods. Historically, roasting was carried out in fixed-bed furnaces or rotary kilns. However, nowadays often fluidized bed systems are used.

[0004] The term roasting serves as a collective term for various chemical reactions. First, it covers all oxidation reactions since many ores contain sulfides that must be oxidized to convert them into oxides or other compounds that can be more easily reduced to metals. For example, pyrite (FeS2) is often roasted to produce iron oxide (Fe2O3) and sulfur dioxide (SO2), which can then be further processed.

[0005] August 7, 2024 O 1 P 382 Moreover, roasting also includes a reduction of volatile components, particularly impurities such as arsenic and antimony, which can otherwise complicate the refining process.

[0006] Another important aspect of a roasting process is the reparation for leaching. In the production of certain metals, roasting is used to prepare the ore for subsequent hydrometallurgical processes like leaching, where the metal is dissolved and extracted from the ore.

[0007] Finally, roasting can also induce the thermal decomposition of carbonates and other compounds, facilitating the liberation of metal oxides.

[0008] The feed system of roasters plays a crucial role in ensuring the efficient and consistent operation of the roasting process. In any metallurgical operation, the precise control of the material feed into the roaster is essential for achieving optimal thermal reactions and maintaining product quality. This is particularly true for fluidized bed roasters, where the uniformity of the material feed directly impacts the fluidization quality and overall efficiency of the roasting process.

[0009] A potential feeding device is an airtight slinger belt, which discharges material above the fluidized bed level and functions as a spreader across the entire reactor cross-section as described in EP 3 294 915 B1 . This device features a belt rotating at high speed, injecting particles at high velocity.

[0010] Alternatively, an airtight screw feeder could be used, which discharges material into or over the fluidized bed surface. The screw feeder includes standard components such as a screw shaft, casing, motor, and a gap / solids overflow arrangement between the end of the rotating screw shaft and the entrance to the fluidized bed. This design serves to protect the rotating screw shaft from high temperatures and facilitates reactions within the screw feeder.

[0011] August 7, 2024 O 1 P 382 Another airtight option is a rotating scraper located at the reactor dome top, below a feeding bin. The feed distribution within the fluidized bed cross-sectional area is achieved through feed pipes extending from the roaster roof to the fluidized bed cross-sectional area.

[0012] The common denominator of these variants is their inability to react to changes in the fed material or upstream devices. Consequently, clumped material can enter the process, which can have far-reaching consequences for the stability of the process, particularly in the case of a fluidized bed reactor. Furthermore, in the event of a component failure or malfunction, there is no means of replacement, necessitating the complete cessation of the process.

[0013] Therefore, the invention is directed to the aim of establishing a continuous material feed which is both reliably and homogeneous.

[0014] This aim is solved with a roaster feed system according to claim 1 which contains at least one rotary table feeder, at least two slinger belt feeders, at least one feed gate valve as well as a lifting device.

[0015] The rotary table feeder (RTF) is designed to regulate the flow of material into the roaster. It typically consists of a rotating table with height-adjustable scrapers that help in splitting the incoming material stream into multiple outgoing streams. This ensures a consistent and evenly distributed feed, which is critical for maintaining uniform temperature and reaction rates within the roaster. The rotary table feeder plays a pivotal role in splitting the incoming material stream into two or more outgoing streams. It's height-adjustable scrapers ensure that the material is evenly distributed across the slinger belt feeders, promoting uniform feeding into the roaster. This consistent distribution is crucial for maintaining the fluidized bed's stability and ensuring efficient roasting.

[0016] August 7, 2024 O 1 P 382 The Slinger belt feeders (SBF) are used to transport the material from the rotary table feeder to the roaster. Each slinger belt feeder is equipped with sensors to monitor vibration and temperature, ensuring that any irregularities in the feed material, such as moisture content or the presence of foreign objects, are detected promptly. These sensors play a vital role in preventing feed interruptions and maintaining the smooth operation of the roaster.

[0017] The at least one Feed gate valves (FGV) is strategically placed along the feed system to control the flow of material into the roaster. These valves are designed to automatically close in the event of a feeder failure or stoppage, preventing the uncontrolled discharge of material and ensuring that the roaster operates within safe and optimal parameters.

[0018] The automatic lifting devices are integrated into the feed system to facilitate the maintenance and adjustment of the scrapers and gate valves. These devices enable the automatic lifting and closing of discharge openings by gate valves, ensuring that any disruptions in the feed process are managed efficiently. This automation reduces the need for manual intervention, enhancing the overall reliability and safety of the system.

[0019] In the event of a feeder failure or stoppage, the feed gate valves close automatically to prevent uncontrolled material flow. The automatic lifting devices then lift the scrapers and close the discharge openings, isolating the failed feeder. The control system subsequently adjusts the material stream and roasting air flow to match the reduced capacity, ensuring that the roaster continues to operate efficiently despite the feeder disruption.

[0020] A Pneumatic actuation is preferably used for these valves, providing reliable and rapid response to any operational changes.

[0021] August 7, 2024 O 1 P 382 The vibration and temperature sensors integrated into the slinger belt feeders continuously monitor the operational status of the feed system. Any anomalies, such as excessive vibrations due to moist feed material or elevated temperatures indicating potential fires, trigger sensor signals. These signals warn operating personnel, preferably acoustically and / or with a warning light, and, if necessary, automatically take the affected feeder out of operation, closing the corresponding feed gate valve to prevent further issues.

[0022] Each slinger belt feeder includes a spillage chute equipped with a shut-off valve. This valve opens at intervals to release any spillages to the ground or a spillage conveyor, preventing material buildup and ensuring that the feed system remains clean and operational.

[0023] To minimize downtime and maintain continuous operation, the feed system includes an automatic changeover mechanism. In case of a feeder failure, this mechanism removes the failed feeder and transports a standby feeder to the operating position. This seamless transition ensures that the roaster receives a consistent material feed without significant interruptions.

[0024] It is preferred that the feed gate valve opens into the roaster, preferably directly. So, very short reaction times are ensured.

[0025] For the reactor type used as the roaster a fluidized bed reactor is particularly preferred since the well-known fixed-bed and rotary kiln systems often suffer from inefficient heat transfer, leading to uneven roasting and higher energy consumption. Moreover, traditional roasting methods typically involve higher operational costs due to their lower efficiency and greater maintenance requirements.

[0026] August 7, 2024 O 1 P 382 Fluidized bed systems have revolutionized the roasting process, offering significant advantages over traditional methods. A fluidized bed roaster consists of a bed of solid particles, typically composed of the ore to be roasted, which are suspended in an upward flow of gas. This setup creates a fluid-like state that enhances the mixing and contact between the gas and the solid particles, leading to several key benefits:

[0027] Fluidized bed systems provide superior heat transfer compared to fixed-bed or rotary kiln systems. The constant mixing of particles ensures uniform temperature distribution throughout the bed, leading to more consistent roasting. In addition, the increased contact between the gas and solid phases in a fluidized bed enhances the reaction rates. This results in faster and more efficient roasting, reducing the time required to process the ore.

[0028] Moreover, fluidized bed systems are more ecologically sound as they are designed to facilitate the capture and treatment of emissions. The high level of control over gas flow and temperature allows for the efficient capture of sulfur dioxide and other gases, minimizing environmental impact. Further, the efficient heat transfer and rapid reaction rates in fluidized bed systems lead to significant energy savings. This makes fluidized bed roasting a cost-effective solution for the metallurgical industry.

[0029] Fluidized bed roasters can handle a wide variety of ore types and compositions, making them versatile and adaptable to different processing requirements. Fluidized bed roasting is particularly advantageous in the processing of sulfide ores. For instance, in the production of zinc, fluidized bed roasters are used to oxidize zinc sulfide (ZnS) to zinc oxide (ZnO) while simultaneously producing sulfur dioxide, which can be captured and used in the production of sulfuric acid. This dual benefit of metal extraction and by-product recovery exemplifies the efficiency of fluidized bed systems.

[0030] August 7, 2024 O 1 P 382 Similarly, in the production of copper, fluidized bed roasting is employed to convert copper sulfide ores into copper oxides, which are then subjected to further processing steps such as smelting and electrorefining. The uniform temperature control and efficient gas-solid interactions in fluidized bed roasters enhance the overall yield and quality of the final metal product.

[0031] Summing up, the adoption of fluidized bed roasting systems has notable environmental and economic benefits. By reducing energy consumption and improving the efficiency of the roasting process, these systems lower the overall carbon footprint of metallurgical operations. Additionally, the effective capture and utilization of sulfur dioxide reduce harmful emissions and create opportunities for the production of valuable by-products. From an economic perspective, the increased throughput and lower operational costs associated with fluidized bed roasting systems translate into higher profitability for mining and metallurgical companies. The ability to process a diverse range of ores with minimal downtime further enhances the economic viability of these systems.

[0032] Fluidized bed roasting systems represent a significant advancement in the field of ore processing. Their superior heat transfer, reaction rates, and emissions control make them the preferred choice for modem metallurgical operations. As the industry continues to seek more efficient and environmentally friendly processing methods, the adoption of fluidized bed technology is likely to grow, driving further innovation and improvements in metal extraction and refining processes.

[0033] The roaster feed system is integrated with advanced control systems that manage the overall operation of the roasting process. These control systems adjust the material stream and roasting air flow based on real-time data from the sensors, ensuring efficient and uninterrupted operation. Upon detecting a feeder failure, the control system reduces the material stream to the rotary table feeder and the

[0034] August 7, 2024 O 1 P 382 roasting air flow to match the operational capacity of the remaining feeders. Once the failed feeder is replaced, the control system restores the material stream and roasting air flow to their original settings, resuming full-capacity operation.

[0035] The feed system of roasters, particularly in fluidized bed systems, is a sophisticated and critical component that ensures the smooth and efficient operation of the roasting process. Through the integration of advanced sensors, automatic lifting devices, and precise control mechanisms, the feed system maintains a consistent material flow, enhances operational reliability, and minimizes downtime. As metallurgical operations continue to evolve, the importance of a robust and efficient feed system in achieving optimal roasting performance cannot be overstated.

[0036] The automated roaster feed system, as described in any of the preceding claims, includes a sophisticated control system. The control system is specifically designed to manage the material stream fed into the rotary table feeder and the roasting air flow. Upon detecting a failure or stoppage in one of the slinger belt feeders, the control system promptly reduces both the material stream and the roasting air flow to match the maximum capacity of the remaining operational slinger belt feeder. This automatic adjustment ensures that the roaster continues to operate efficiently without overloading the functional feeder, thereby preventing any potential disruption in the roasting process.

[0037] The control system possesses the capability to automatically manage various components once a failed slinger belt feeder is replaced by a standby unit. Specifically, the system will reopen the feed gate valve and the shut-off gate at the rotary table feeder. Concurrently, it will also lower the scraper back to its original position. This automated sequence ensures that the system can quickly return to normal operation with minimal manual intervention, maintaining a steady flow of material into the roaster and ensuring continuity in the roasting process.

[0038] August 7, 2024 O 1 P 382 Further enhancing the efficiency of the roaster feed system, one embodiment of the control system is designed to restore the roasting air flow and the material feed stream to their former capacities once the failed slinger belt feeder has been successfully replaced. This automatic restoration process ensures that the roaster can resume its optimal performance levels without delay, thereby maximizing productivity and minimizing downtime.

[0039] Preferably, the control system is equipped with the functionality to make real-time adjustments to the material stream fed into the rotary table feeder and the roasting air flow based on the current operational status of the slinger belt feeders. This dynamic adjustment capability is crucial for ensuring efficient and uninterrupted operation of the roaster. By continuously monitoring the status of the feeders and adjusting the material and air flow accordingly, the system maintains a stable and efficient roasting process, reducing the likelihood of interruptions and ensuring consistent product quality.

[0040] Summing up, the automated roaster feed system’s control system plays a pivotal role in ensuring the efficient and seamless operation of the roasting process. Key functionalities include a rapid identification of feeder failures or stoppages and immediate adjustment of material and air flow to prevent overload and maintain operational stability. Further, it covers a quick transition to normal operations by reopening valves and adjusting scrapers once a standby feeder replaces a failed unit, minimizing manual intervention. Moreover, an automatic restoration of previous material and air flow capacities post-replacement is possible, ensuring the roaster returns to optimal performance swiftly. Consequently, a continuous monitoring and adjustment of material and air flow based on the operational status of feeders, ensuring efficient and uninterrupted roasting.

[0041] August 7, 2024 O 1 P 382 So, this sophisticated control system enhances the reliability, efficiency, and productivity of the automated roaster feed system, making it a critical component in modem roasting operation.

[0042] Furthermore, the invention encompasses a process as described in claim 14, which can be implemented using a feed system according to any of claims 1 through 13. It goes without saying that all features described for the plant are also potential embodiments of the claimed process.

[0043] The process begins with splitting an incoming material stream into two outgoing material streams using a rotary table feeder (RTF). The rotary table feeder is equipped with height-adjustable scrapers that can be precisely positioned to ensure even distribution of the material. This mechanism allows for accurate control of the material flow, ensuring that the subsequent feeders receive a balanced and consistent supply.

[0044] The outgoing material streams from the RTF are directed to at least one pair of slinger belt feeders (SBFs). Each slinger belt feeder is preferably equipped with vibration and temperature sensors to monitor their operational status. The vibration sensors detect any abnormal vibrations caused by issues such as moist feed material sticking to the belt or worn bearings, while the temperature sensors monitor for overheating or other temperature-related problems.

[0045] The material from each slinger belt feeders is then passed through at least one feed gate valve into the roaster. The feed gate valve(s) is / are crucial components that control the flow of material into the roaster, ensuring that the feed rate remains consistent and manageable. The gate valve(s) can be automatically adjusted to regulate the material flow based on the real-time operational status of the feeders.

[0046] August 7, 2024 O 1 P 382 A key feature of this process is its ability to automatically close at least one feed gate valve associated with each slinger belt feeder upon failure or stoppage of the corresponding slinger belt feeder. When a feeder failure is detected — either through the vibration or temperature sensors — the control system triggers the closure of the relevant gate valves to prevent unregulated material flow into the roaster. This automatic response helps maintain the stability of the roasting process and prevents potential damage or inefficiency that could arise from feeder malfunctions.

[0047] The described process offers several significant advantages, particularly an enhanced reliability since by splitting the incoming material stream and using multiple feeders, the system reduces the risk of total feed interruption due to a single feeder failure. Further, the integration of vibration and temperature sensors provides real-time monitoring of feeder conditions, allowing for prompt detection and response to potential issues. In addition, the automatic closure of feed gate valves in response to feeder malfunctions ensures the continuous and safe operation of the roaster. So, the precise control of material flow through adjustable scrapers and gate valves ensures a consistent and optimal feed rate to the roaster, improving the overall efficiency of the roasting process.

[0048] In conclusion, the process according to this invention provides a robust and automated solution for the continuous and safe feeding of material into a roaster, addressing the common challenges associated with traditional feeding systems and enhancing the reliability and efficiency of the roasting operation.

[0049] Further developments, advantages and possible applications of the invention can also be taken from the following description of the drawing. All features described and / or illustrated form the subject-matter of the invention per se or in any combination, independent of their inclusion in the claims or their back-reference.

[0050] August 7, 2024 O 1 P 382 Fig. 1 shows schematically a roasting reactor with a feed system according to the invention.

[0051] Figure 1 illustrates a feeding system according to the present invention, integrated with a roasting reactor 40 designed for the roasting or partial roasting of particles. The particles are introduced via conduit 11 or another transporting device to at least one feed belt conveyor 12. The feed belt conveyor 12 can be configured as a weighting belt conveyor for precise material handling.

[0052] From the feed belt conveyor 12, the particles are conveyed through a tube 13 or directly to at least one rotary feed table 10. The rotary feed table 10 then distributes the particles to slinger belt feeders 20', 20" either directly or via tubes 2T, 21". In this example, two slinger belt feeders 20', 20" are depicted, though the system can accommodate multiple pairs as needed. The key feature is the arrangement of the feeders in pairs to maintain system redundancy, which is crucial for the invention's concept.

[0053] The material from the slinger belt feeders 20', 20" is then conveyed through tubes 3T, 31" into the reactor 40, passing through feed gate valves 30', 30". As illustrated, each slinger belt feeder 20', 20" can be connected to the reactor 40 via separate tubes 3T, 31" with individual feed gate valves 30', 30". Alternatively, the material streams from multiple slinger belt feeders can be combined into fewer tubes, necessitating fewer valves.

[0054] In this example, the roasting reactor 40 is depicted as a fluidized bed reactor. However, other reactor types, such as rotary kilns, are also applicable. In case of a roasting rector 40 designed as a fluidized bed reactor, the introduced particles form a fluidized bed 41 above a reactor nozzle grid 42 due to the fluidizing gas injected through the grid via conduit 43.

[0055] August 7, 2024 O 1 P 382 To control the reactor temperature, additional water can be added through conduit 44, with the water being sprayed above the fluidized bed 41 , often using not- shown water lances.

[0056] Particles are withdrawn from the fluidized bed 41 via conduit 45. Meanwhile, very light particles are transported into a freeboard zone 46 above the fluidized bed 41 and then removed along with the fluidizing gas through conduit 47. The particle / gas mixture from conduit 47 is fed into a cyclone 50, where the particles are separated from the gas stream. The gas stream exits the cyclone 50 via conduit 51 , while the particles are directed into conduit 45 through conduit 52.

[0057] August 7, 2024 O 1 P 382 List of references

[0058] 10 rotary feed table 11 conduit

[0059] 12 feed belt conveyor

[0060] 13 tube

[0061] 20', 20" slinger belt feeder 21 ', 21" tube 30', 30' feed gate valves

[0062] 31 ', 31 ' tube 40 roasting reactor 41 fluidized bed 42 reactor nozzle grid 43 - 45 conduit

[0063] 46 freeboard zone

[0064] 47 conduit

[0065] 50 cyclone

[0066] 51 , 52 conduit

[0067] August 7, 2024 O 1 P 382

Claims

Claims1. An automated roaster feed system, comprising a rotary table feeder (10) equipped with at least one height-adjustable scraper for splitting an incoming material stream into two outgoing material streams, at least one pair of slinger belt feeders (20', 20") for receiving the outgoing material streams from the rotary table feeder, each equipped with vibration and temperature sensors, at least one feed gate valve (30', 30") associated with the slinger belt feeders (20', 20"), configured to automatically close when the corresponding slinger belt feeders (20', 20") fails or stops, and at least one automatic lifting device for the at least one scrapers, enabling an automatic lifting and closing of discharge openings by the feed gate valve (30', 30") upon failure or stoppage of a slinger belt feeder (20', 20").

2. An automated roaster system according to claim 1 , characterized in that the feed gate valve(s) (30', 30") is / are pneumatically actuated.

3. An automated roaster feed system according to claim 1 or 2, characterized in that each slinger belt feeder (20', 20") is equipped with vibration sensors configured to detect vibrations caused by moist feed material stuck on rotating rollers or the belt and / or due to worn bearings.

4. An automated roaster feed system according to claim 3, characterized in that the sensors are configured to emit a sensor signal used to warn operating personnel and / or take the respective slinger belt feeder (20', 20") out of operation.

5. An automated roaster feed system according to claim 4, characterized in that the temperature sensors are configured to emit a sensor signal usedAugust 7, 2024 O 1 P 382to stop the respective slinger belt feeder (20', 20") and closing the feed gate valve (30', 30").

6. An automated roaster feed system according to any of the preceding claims, characterized in that each slinger belt feeder (20', 20") includes a spillage chute equipped with a shut-off valve, configured to open at intervals to release spillages to the ground or a spillage conveyor.

7. An automated roaster feed system according to any of the preceding claims, characterized in that each slinger belt feeder (20', 20") comprises an automatic changeover mechanism, wherein a failed each slinger belt feeder is automatically removed, and a stand-by slinger belt feeder is transported to the operating position.

8. An automated roaster feed system according to any of the preceding claims, characterized in that the feed gate valve(s) (30', 30") open(s) into a roasting reactor (40).

9. An automated roaster feed system according to claim 8, characterized in that the roasting reactor (40) is a fluidized bed reactor wherein particles are fluidized with fluidizing gas.

10. An automated roaster feed system according to any of the preceding claims, characterized in that the roaster feed system comprises a control system configured to reduce the material stream to the rotary table feeder (10) and the fluidizing gas flow to the maximum capacity of the operational slinger belt feeder (20) upon detection of a slinger belt feeder (20) failure or stoppage.August 7, 2024 O 1 P 38211. An automated roaster feed system according to claim 10, characterized in that the control system is configured to automatically reopen the feed gate valve(s) (30', 30") and / or a shut-off gate at the rotary table feeder (10), and lower the scraper to its original position once the failed slinger belt feeder (20', 20") is replaced by a stand-by slinger belt feeder.

12. An automated roaster feed system according to claim 10 and 11 , characterized in that the control system is configured to increase the fluidizing gas and material feed stream to the rotary table feeder (10) to their former capacities.

13. An automated roaster feed system according to any of claims 10 and 12, characterized in that the control system is configured to adjust the material stream to the rotary table feeder (10) and the fluidizing gas based on the operational status of the slinger belt feeders (20', 20") to ensure efficient and uninterrupted operation.

14. A process for a safe continuously feeding material into a roaster, comprising the following steps: i) splitting an incoming material stream into two outgoing material streams by using a rotary table feeder (RTF) equipped with at least one height-adjustable scraper, ii) directing the outgoing material streams to at least one pair of slinger belt feeders (SBFs), each preferably equipped with vibration and temperature sensors to monitor operational status, iii) passing the material from each slinger belt feeder through at least one feed gate valve (FGV) into the roaster and iv) automatically closing at least one feed gate valve associated with a slinger belt feeder upon failure or stoppage of the corresponding slinger belt feeder.August 7, 2024 O 1 P 382

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