The Enigmatic Shadows of Panzhou: A Coal Preparation Plant Adventure of Two Female College Students (2)

Uncle Li was silent for a moment before walking over to the monitor. He examined it for a few seconds, then shook his head. "Nothing to worry about, it’s probably just some interference with the system. How about we go check it out?"

Although still fearful, Gu Xiaotong and Li Xiaoning didn’t want to appear weak, so they gathered their courage and followed Uncle Li to the filter press workshop.

Exploring the Filter Press Workshop at Night

The workshop looked even more ominous at night. The long production line stretched out in a row, and the massive silhouettes of the filter presses loomed menacingly in the darkness. The occasional sound of machinery seemed like some mysterious breathing, and the air was damp, mixed with a faint smell of coal dust.

"Hey! You two are just scaring yourselves. Ghosts? Nonsense!" Uncle Li’s tone was light, but his footsteps echoed loudly in the silent workshop, making the place feel even more unsettling.

As they slowly walked towards the center of the workshop, a shadow suddenly darted overhead, accompanied by a rush of wind. Gu Xiaotong screamed, nearly jumping out of her skin. "It’s here! It’s back!"

Uncle Li looked up and suddenly burst into laughter. "Girls, there’s no ghost—it’s just a swallow!"

Sure enough, a little swallow had flown over their heads and into a small nest it had built in the corner of the workshop’s ceiling. The sound of its wings flapping in the quiet environment had spooked them.

"A swallow? What’s it doing here?" Li Xiaoning asked, surprised.

"It’s because the environment here is good," Uncle Li chuckled. "Our plant’s environmental management is top-notch. Just look at the greenery, the drainage system, even the dust control here—it’s all up to strict environmental standards. If swallows are willing to make their home here, it means the air quality is pretty decent."

The two students exchanged relieved glances, finally able to laugh off their earlier fear. The environmental measures they had studied during the day were not just about regulatory compliance—they had also provided a safe haven for these little birds.

Fault Diagnosis

Although the "ghost" mystery was solved, the flickering lights in the workshop still needed addressing. They decided to inspect the electrical system thoroughly. Uncle Li led them through the workshop, checking the power lines, and eventually discovered that some old wiring had worn out over time, causing a short circuit.

"Looks like this is the culprit," Uncle Li clapped his hands and smiled. "It’s not a big deal; I’ll have the electrician fix it first thing in the morning. But tonight, just be careful and don’t let these little issues scare you."

Standing in the workshop late at night, listening to Uncle Li, Gu Xiaotong and Li Xiaoning felt the terror of just moments ago dissipate. They went from feeling tense and anxious to light-hearted and confident. Though they had faced a "ghostly encounter" during their shift, they also gained a deeper understanding of the importance of every detail in the coal preparation plant.

Marks of Growth

This night became an unforgettable experience for Gu Xiaotong and Li Xiaoning on their first shift. Not only did they experience the eeriest "paranormal event" in the plant, but they also witnessed the plant’s excellent environmental management and uncovered a minor fault in its operations. Through this, they grew, realizing that whether it’s the technical challenges of the coal slurry system or the small daily hiccups, they’re all part of the journey they will face in the future. This experience strengthened their resolve to overcome the challenges in solving the problems at the coal preparation plant.

7. Unexpected Crisis and Breakthroughs

However, the smooth progress didn’t last long. In a bid to increase profitability, the Jigangping Coal Preparation Plant began processing external coal. The significant difference in coal quality between the external coal and the local coal from Jigangping, along with the higher level of mud content, caused a massive surge in the load on the coal slurry system. The system, already operating at its design capacity, was overwhelmed by the influx of external coal, leading to a temporary halt in production. The discharge of coal slurry also reached critical environmental thresholds.

Faced with this sudden crisis, Gu Xiaotong and Li Xiaoning didn’t back down. They worked tirelessly alongside the workers, repairing the equipment and installing a predictive maintenance system to monitor the operational status and parameters of the machinery in real-time. They also recalibrated the dosing system, adjusted the operating parameters of the sedimentation tanks, and added a temporary drainage system at the centrifuge to prevent the system from being overloaded. Through their efforts, production gradually returned to normal.

Additionally, they drew on advanced environmental technologies to implement secondary treatment of residual chemicals in the coal slurry, reducing the pollutant concentration in the discharge water. Their improvements not only enabled the coal slurry treatment system to withstand the sudden surge in demand but also demonstrated increased efficiency and stability in routine operations.

8. An Unfinished Journey

At the story’s end, Gu Xiaotong and Li Xiaoning stood atop a mountain in Pan County, overlooking the coal preparation plant where they had poured so much of their effort. Although they had successfully addressed some of the coal slurry system’s issues, they knew that fully overcoming the technical challenges in this industry would require much more research and exploration.

“This is a marathon, not a sprint,” Gu Xiaotong said with a smile.

“Exactly,” Li Xiaoning agreed, nodding. “We’ve got a long way to go.”

They understood that in the days to come, they would continue to collaborate with industry colleagues to tackle these challenges. Step by step, they would strive to solve the issues of the coal slurry system, not just for the plant’s production efficiency but also to protect the land they deeply cherished—the lush mountains and clear waters of Guizhou.

Work Note

Coal Slurry Water System

The coal slurry water system is a crucial part of a coal preparation plant, used to handle coal slurry and water, recover valuable coal from the slurry, and treat wastewater. The system aims to maximize the recovery of useful components in the coal slurry, reduce environmental pollution, and improve both economic and environmental benefits of the plant.

Components of the Coal Slurry Water System

1. Coal Slurry Collection Pool: The starting point of the coal slurry water system, collecting coal slurry water generated from various processes in the coal preparation plant.

2. Sedimentation Tank: Used to settle solid particles in the coal slurry water, separating the clear liquid from the sediment.

3. Thickener: Further concentrates solid particles in the coal slurry water, reducing the volume of liquid that needs to be processed.

4. Filter Press: Dehydrates the concentrated coal slurry, producing a coal slurry cake with lower moisture content.

5. Clear Water Pool: Collects the clear water overflow from the sedimentation tank and thickener. The treated clear water can be recycled in the coal washing process.

6. Reagent Addition System: Adds flocculants, settling agents, and other chemicals to the coal slurry water to enhance solid-liquid separation.

Working Principle of the Coal Slurry Water System

1. Collection and Transport: The system first collects coal slurry water from various processes in the coal preparation plant and transports it via pipelines to the coal slurry collection pool.

2. Sedimentation Separation: The coal slurry water enters the sedimentation tank where gravity allows solid particles to settle and form a sediment layer, while the clear liquid overflows into the clear water pool.

3. Thickening: The slurry at the bottom of the sedimentation tank is pumped to the thickener, which further concentrates the solid particles, reducing the liquid volume.

4. Filtration and Dehydration: The concentrated slurry is fed into the filter press, which uses mechanical pressure to squeeze out water, forming a coal slurry cake with lower moisture content. These cakes can be further processed or stored.

5. Water Recycling: The clear liquid in the clear water pool is treated and recycled back into the coal washing process, achieving water resource recycling.

Optimization of the Coal Slurry Water System

To improve the efficiency and effectiveness of the coal slurry water system, the following measures can be implemented:

1. Optimize Sedimentation Tank and Thickener Design: Enhance solid-liquid separation effectiveness by improving tank design and thickener operation.

2. Select Appropriate Reagents: Use suitable flocculants and settling agents to improve the settling speed and efficiency of coal slurry particles.

3. Regular Maintenance and Inspection: Conduct routine maintenance and checks on equipment to ensure proper system operation.

4. Apply Automation Control Technology: Implement automated control systems for real-time monitoring and control of the coal slurry water treatment process.

These measures can effectively improve the treatment efficiency of the coal slurry water system, reduce environmental impact, and ensure thorough utilization of coal resources.

Major Issues in the Coal Slurry Water System - "Coarse Runoff"

"Coarse runoff" refers to the failure to effectively separate larger coal particles during the treatment of coal slurry water, causing these coarse particles to enter subsequent processing stages or the water recycling system. This issue impacts overall system efficiency and treatment effectiveness. Detailed description of coarse runoff:

1. Causes of Coarse Runoff

1). Poor Slurry Flow Properties: High viscosity and poor flow properties of the coal slurry can lead to coarse runoff. Additionally, high solid content in the slurry can impede flow, exacerbating coarse runoff.

2). Poor Flow in the Coal Slurry Layer: The coal slurry layer faces resistance due to flow properties and material friction, resulting in poor movement and increased coarse runoff.

3). High Internal Viscosity: Increased internal viscosity of the coal slurry hinders particle movement, affecting slurry flow and causing coarse runoff.

2. Impact of Coarse Runoff

Based on production practices and fault handling experience, coarse runoff issues can be categorized into system-wide coarse runoff, coarse coal recovery system runoff, and fine coal slurry runoff. Any upstream issue can ultimately lead to coarse runoff downstream. Impacts of coarse runoff include:

1). Increased Equipment Wear: Coarse particles entering subsequent stages accelerate equipment wear and reduce equipment lifespan.

2). Decreased Treatment Efficiency: The presence of coarse particles can disrupt subsequent processing, lowering efficiency and effectiveness.

3). Reduced Water Quality: Coarse runoff increases solid particles in the recycling system, affecting water quality and complicating treatment.

4). Increased Production Costs: Equipment wear and decreased efficiency raise maintenance and operational costs.

5). Environmental Pollution Risk: Unprocessed coarse particles in the discharge water can lead to environmental pollution.

3. Solutions for Coarse Runoff

To address coarse runoff issues in the coal slurry water system and improve efficiency and stability, the following solutions are recommended:

1). Optimize Sedimentation Tank Design and Operation:

Increase Tank Capacity: Expand sedimentation tank volume to enhance processing capability and allow more time for particle settlement.

Improve Tank Shape: Modify design, such as adding inclined plates or tubes, to improve settling efficiency.

Regular Cleaning: Prevent sediment accumulation by maintaining the tank’s effective volume.

2). Equipment Maintenance and Upgrades:

Regular Maintenance: Ensure proper operation of filter presses, centrifuges, and flotation machines.

Equipment Upgrades: Introduce more efficient separation equipment to improve separation effectiveness.

Spare Parts Management: Maintain adequate stock of critical spare parts to minimize downtime.

3). Adjust Slurry Concentration:

Control Feed Concentration: Adjust coal slurry water feed concentration to fall within optimal processing ranges.

Pre-Treatment Processes: Conduct pre-thickening or dilution to optimize treatment conditions.

4). Improve Process Flow:

Redesign Flow Process: Optimize existing processes to handle different particle sizes effectively.

Multi-Stage Separation: Implement multi-stage separation to gradually remove particles of various sizes.

Add Buffer Equipment: Introduce buffer equipment between process stages to balance loads and prevent sudden changes.

5). Real-Time Monitoring and Adjustment:

Install Monitoring Equipment: Use online monitoring devices to track particle size distribution and concentration changes.

Data Analysis: Analyze monitoring data to detect and resolve coarse runoff issues promptly.

Automated Control Systems: Implement automated systems to adjust process parameters based on real-time data.

6). Water Quality Management:

Improve Recycled Water Quality: Optimize the recycling system to control solid particle content.

Enhance Recycled Water Treatment: Increase treatment processes, such as sedimentation and filtration, to improve water quality and reduce system interference.

By applying these solutions, the efficiency of the coal slurry water system can be enhanced, environmental impacts minimized, and coal resource utilization maximized.

Coarse Running of Sludge Centrifuge

Nowadays, the issue of coarse running in sludge centrifuges is particularly important. The problem mainly involves the size of the sludge particles, which affects processing efficiency and product quality. Solutions to this problem can be categorized into two main areas: prevention and treatment.

1. Preventive Measures

1) Equipment Maintenance

Replacing the Screen Basket: If the screen basket’s gap wears out or the basket is damaged, it should be replaced promptly.

Checking the Inlet: Ensure that the inlet is correctly inserted into the screen basket and use the main machine manufacturer's parts to avoid inlet wear and ensure the height of the screen basket is correct.

Replacing the Protection Ring: When the outlet protection ring is worn, it should be replaced with a new one.

Adjusting the Rotation Direction: If the main machine's rotation direction is incorrect, the motor's rotation direction should be adjusted.

2) Adding Equipment and Modifications

Installing a Coarse Interception Device: Before the desliming screen, desliming screen, and centrifuge screen basket are damaged, a coarse interception device should be added for filtration to prevent large particles from entering the next stage.

Installing a Coarse Running Detection Device: A coarse running detection device should be added at the hopper to trigger an alarm promptly when coarse running occurs, preventing the problem from escalating.

Integrating Sweeping Water into the System: Modify the original centralized water pump pipeline to feed into the desliming screen. After being filtered through a 2mm screen plate, it should enter the coarse sludge water system for recovery, ensuring that the sludge water entering the thickening tank has been dewatered, stabilizing the feed to the thickening tank.

2. Treatment Measures

1) Equipment Adjustments

Removing Sludge from the Differential Platform: Weld two symmetrical iron plates under the bell cover to scrape off accumulated sludge.

Clearing Sludge from the Centrifuge Overflow Trough: Install a flushing water pipe between the two overflow troughs to supply clean water promptly during operation, flushing away accumulated sludge and keeping the trough clear.

2) Process Optimization

Adding Lubricants: Reduce the viscosity of the sludge to decrease the adhesion between particles. Lubricants can make relative movement between sludge particles easier, improving sludge flow.

Improving Sludge Layer Structure: Optimize the structure of the sludge layer, increase permeability, reduce solid content, decrease sludge resistance, and reduce the risk of coarse running.

Stabilizing Cyclone Feed Parameters: Add a water supply pipe at the sludge pump feed pipeline to dilute the sludge water, ensuring that the sludge water concentration entering the cyclone is within limits, reducing the occurrence of cyclone blockages.

Adjusting Sludge Water Concentration: Control the feed concentration of the sludge water to ensure it is within the equipment's processing capacity. Adjust the concentration of the sludge water through pretreatment processes, such as thickening or dilution.

3. Specific Example

Cleaning Sludge from the Chute: Install a self-made cleaning device, such as a triangular cleaning device, on the scraper discharge centrifuge to replace manual cleaning of sludge from the chute. When the screen basket operates, the device automatically scrapes off the sludge from the surrounding chute, preventing sludge from entering the centrifuge liquid.

Conclusion

Coarse running of sludge is a significant issue that affects the efficiency of sludge processing. Poor sludge flowability, unreasonable material structure, and high internal viscosity are factors that can lead to coarse running. To effectively reduce the occurrence of coarse running, measures such as adding lubricants, improving the sludge layer structure, combined with equipment maintenance and process optimization, should be adopted to improve the overall processing efficiency of the sludge water system, reduce environmental pollution, and achieve effective resource utilization.

Author Bios:

Diandian Li

Diandian Li is a third-year undergraduate student majoring in Mineral Processing Engineering at China University of Mining and Technology (Beijing). She has excellent academic performance, receiving the university’s special scholarship and the top prize in the university debate team. She has participated in social practice, earning the title of Beijing Star Volunteer. As the team leader, she participated in social practice and won both an outstanding practice award and an individual excellence award. She also serves as a key member of the student union office and the deputy head of the new media department of the university's employment and entrepreneurship association. During her time at university, she has participated in related academic competitions in her field and won third prize in Beijing in the 9th "Internet+" College Student Innovation and Entrepreneurship Competition.

She is a volunteer for the Sichuan Alumni Association of China University of Mining and Technology, having organized large-scale venture capital activities and participated in Chinese-funded enterprises' business activities in Indonesia. She also co-hosted the Indonesian Chinese-funded football league. During the summer, she served as an international marketing intern at HOT (Chengdu) Industries Co Ltd.

Yue Yin

Yue Yin is a third-year undergraduate student majoring in Mineral Processing Engineering at China University of Mining and Technology (Beijing). She has performed well academically, receiving university-level scholarships. She participated in social practice and won second prize for an excellent practice report. She has also been involved in multiple volunteer activities during her time at university and was named a Beijing Star Volunteer. She has served as the class psychological counselor, an outstanding member of the Youth League Committee, and the head of the organization department of the glimmer Volunteer Association. She won the championship in a women's five-a-side football tournament and achieved excellent results in related academic competitions in her field.

Yue is also a volunteer for the Sichuan Alumni Association of China University of Mining and Technology, having participated in Chinese-funded enterprises' business activities in Indonesia and organized multiple large-scale venture capital activities. During the summer, she served as an international marketing intern at HOT (Chengdu) Industries Co Ltd.