Mobile Stacker Coal Stockpiling Solution

An open-pit factory specializing in coal processing and transshipment has faced challenges due to capacity expansion in recent years, with daily coal stockpiling increasing from 8,000 tons to 12,000 tons. The traditional combination of loaders and fixed stackers has revealed significant shortcomings: fixed stackers can only stack in one direction, with a single unit handling less than 300 tons per hour, unable to match the factory’s coal receiving capacity of 450 tons per hour, leading to coal accumulation at the unloading area. The stacking height is limited to 8 meters, and the 54-meter-long stockpiling area can only accommodate 60,000 tons of inventory, necessitating frequent transfers to temporary stockyards, which further increases losses. Open-air stacking results in coal dust emissions of 22 mg/m³, far exceeding the 10 mg/m³ limit set by the Comprehensive Emission Standard for Air Pollutants, leading to frequent complaints from surrounding areas. Additionally, coal dust dispersion and transfer processes cause a coal loss rate of 5%, resulting in significant material waste. The stockpiling area has a natural slope of 12°, which fixed stackers cannot adapt to, requiring additional site leveling. During the rainy season, water infiltration causes coal caking, affecting subsequent processing and accelerating equipment corrosion, with annual maintenance frequency exceeding 12 times and high operational costs.

To address these bottlenecks, the factory required suppliers to provide a coal stockpiling solution that is “highly efficient, environmentally sealed, and adaptable to site conditions,” with seamless integration of equipment for the entire process of “coal receiving-feeding-stacking” to ensure compatibility with the existing production chain. Based on on-site surveys (terrain, weather, coal characteristics) and its full product line parameters, ZOOMRY designed a comprehensive solution centered on a radial telescopic stacker, complemented by a truck unloader and a hopper feeder. This solution leverages the strengths of each piece of equipment to form a seamlessly integrated “receiving-feeding-stacking” stockpiling system.

Project Overview

Core Requirements

The factory’s requirements revolve around four key dimensions: “precise parameters, system integration, site adaptability, and compliance reliability,” fully aligned with the characteristics of open-pit coal stockpiling. In terms of parameters, the core stockpiling equipment must achieve a handling capacity of ≥450 tons per hour, a belt width of 1200 mm, a stacking length of 54 meters, and adaptability to a 12° natural slope, with radial rotation and telescopic functions to ensure full coverage of the 54-meter stockpiling area. For system integration, supporting equipment for coal receiving and feeding is required to achieve a closed-loop process of “truck unloading-uniform feeding-efficient stacking” to avoid interruptions in intermediate stages. For site adaptability, the equipment must withstand open-pit conditions, including high temperatures (40°C), low temperatures (-5°C), and rainwater, with core components (rollers, motors) having a protection rating of ≥IP55. For compliance and maintenance, dust emissions must be ≤10 mg/m³, the equipment’s overall service life must be ≥15 years, and operational training and spare parts support must be provided to ensure the factory’s maintenance team can operate independently.

Core Objectives

1. Efficiency Compliance: The stockpiling system must achieve a stable handling capacity of ≥450 tons per hour, with the 54-meter stockpiling area’s inventory capacity increased to over 80,000 tons, eliminating the need for temporary transfers.
2. Environmental Compliance: Dust emissions must be controlled within 10 mg/m³, and coal loss rate reduced to below 1%.
3. Site Adaptability: The equipment must adapt to a 12° slope without additional site leveling, with a coal caking rate during the rainy season of ≤1%.
4. Cost Optimization: Compared to traditional methods, annual maintenance costs must be reduced by 30%, and the initial equipment investment must offer a cost-performance advantage over international brands.

Mobile Stacker Coal Stockpiling Solution Equipment

Core Equipment

To meet the project’s 450-ton-per-hour coal stockpiling demand, ZOOMRY selected the ZR120SF radial telescopic stacker as the core equipment.

High Stockpiling Efficiency

The ZR120SF radial telescopic stacker features three adjustable functions: “radial rotation + telescoping + luffing.” It offers a radial rotation angle of ±120°, a telescopic range of 10–22 meters (flexibly covering the entire 54-meter stockpiling area), and a luffing angle range of 0–18° (easily adapting to the site’s 12° natural slope without additional leveling). Through a PLC-controlled automatic stacking program (supporting multiple stacking modes such as “herringbone” and “circular”), it avoids dead zones in coal stacking, increasing the 54-meter stockpiling area’s inventory capacity to 85,000 tons, a 28% improvement over traditional fixed stackers.

In terms of hardware, the ZR120SF is equipped with a 1200 mm wide conveyor belt (precisely suited for coal particle sizes of 0.5–10 mm), with a belt speed of up to 3.15 m/s and a maximum theoretical handling capacity of 1500 m³/h (equivalent to approximately 1275 tons per hour based on a coal bulk density of 0.85 t/m³). In actual operation, variable frequency control stabilizes the capacity at 460 tons per hour, not only meeting the current 450-ton-per-hour demand but also providing ample redundancy for future capacity upgrades. The power system uses an efficient drive unit paired with a hard-tooth-surface reducer (transmission efficiency ≥96%), ensuring long-term stable operation.

Sealed and Environmentally Friendly Design

The stacker’s discharge end is equipped with a non-powered dust suppression chute with an internal airflow buffer chamber, effectively reducing airflow speed during coal discharge to minimize dust generation. The conveyor belt adopts an overlapping sealed structure (overlap ≥120 mm) combined with rubber sealing skirts at the discharge end, completely blocking dust escape routes. Additionally, a UV-resistant transparent dust cover is installed on the stacker’s cantilever section, facilitating open-pit inspections while further reducing the impact of wind on coal dust dispersion, ultimately controlling system dust emissions to within 8 mg/m³. Moreover, the sealed conveying and stacking structure isolates open-pit rainwater, reducing the coal caking rate during the rainy season to 0.8%, eliminating the need for additional crushing processes and associated energy and labor costs.

Enhanced Durability for Open-Pit Conditions

The chassis adopts a lattice frame design made of high-grade carbon steel, with a 30% improved strength-to-weight ratio, capable of stably supporting heavy loads and adapting to 12° slope operations. The travel system uses eight solid tires with a ground pressure of ≤0.08 MPa, effectively preventing equipment from getting stuck in soft open-pit terrain. The hydraulic power unit, equipped with a 500L oil tank and an integrated oil temperature control system, operates reliably in temperature ranges of -5°C to 40°C, preventing oil solidification in low temperatures or degradation in high temperatures, reducing hydraulic component failure rates by 40%.

Supporting Equipment

To ensure seamless integration from truck unloading to stacker operation, the solution includes two types of core equipment, both independently developed by ZOOMRY and compliant with technical specifications:

• ZRLS-TU1400 wheel-type truck unloader: As the coal receiving equipment, it features a 1400 mm belt width and a handling capacity of 200–1000 tons per hour, suitable for the factory’s commonly used 30-ton dump trucks. The equipment includes two hydraulically adjustable ramps (6.7° slope), allowing trucks to drive directly onto the unloading platform without reversing. Rubber sealing skirts at the ramp base reduce dust emissions during unloading, and a vibrating feeding device adjusts the discharge rate based on the stacker’s operating status, preventing coal accumulation at the unloading area and aligning the “receiving-stacking” rhythm.
• ZR120D hopper feeder: Positioned between the truck unloader and the stacker, it has a hopper capacity of 5 m³ and uses an 18.5 kW variable-frequency motor to adjust feeding rates in real-time, ensuring a stable coal flow of 450 tons per hour to the stacker, avoiding overload or underload. The hopper’s inner walls are lined with 12 mm thick wear-resistant ceramic plates to withstand coal abrasion and extend service life. A rainproof canopy (made of color-coated steel) prevents rainwater from entering the hopper, avoiding coal caking and ensuring smooth feeding.

Core Components

All critical components are independently manufactured by ZOOMRY, with performance surpassing national and industry standards, supporting long-term system reliability:

• Rollers and Pulleys: Both the stacker and truck unloader use silent rollers (133 mm diameter, suited for 1200 mm belt width), with radial runout ≤0.4 mm (better than the national standard of 0.5 mm) and water ingress ≤95 g after a 72-hour immersion test (better than ZOOMRY’s standard of 100 g), suitable for open-pit wet environments. Pulleys are made of 40Cr forged material (159 mm diameter) with diamond-patterned rubber coating (friction coefficient ≥0.4) to prevent coal slippage, with ovality <1.5 mm, subjected to ultrasonic testing and stress-relief tempering, offering a service life exceeding 50,000 hours.
• Cleaning and Safety Components: The stacker is equipped with two PU cleaning scrapers (one at the head, one at the tail) with ≥95% belt contact, effectively removing residual coal dust to prevent belt misalignment due to material adhesion. It also features “dual safety protection”—a belt misalignment switch (alarms when deviation exceeds 5 mm) and a hydraulic winch self-locking system (locks within 0.01 seconds after power failure, preventing telescopic arm collapse), ensuring operational safety in unattended open-pit conditions.

Project Implementation

Preliminary Survey

ZOOMRY dispatched a five-person technical team to the open-pit factory for a 10-day survey, completing: 3D terrain mapping of the 54-meter stockpiling area using a total station, accurately marking the 12° slope distribution and drainage points to optimize the stacker’s track layout and avoid water accumulation during the rainy season; laboratory testing of coal samples for flowability, abrasiveness, and moisture content to determine parameters such as belt speed and roller spacing; and development of an open-pit protection plan based on local weather data (high/low temperatures, rainy season distribution), including dust cover layout and hydraulic oil temperature control settings.

Manufacturing

All equipment and components were produced at ZOOMRY’s Hebei factory, fully integrated into ISO 9001 quality management and ISO 14001 environmental management systems. The radial telescopic stacker’s chassis frame underwent a 24-hour static load test (loaded at 1.2 times the rated load without deformation). Rollers underwent a 1000-hour no-load test to verify sealing and rotational resistance (≤2 N, better than the national standard of 3 N). The truck unloader’s hydraulic system completed a 72-hour cycle test to ensure no leaks. Factory representatives conducted on-site acceptance, confirming all parameters met contract requirements, with exceptional results in open-pit durability tests (high/low temperature cycles, rain exposure).

Installation and Commissioning

ZOOMRY deployed an eight-person installation team to the site, using a “modular assembly + rainproof construction” approach. The radial telescopic stacker’s main body was divided into five segments (each approximately 10–12 meters), pre-assembled at the factory, requiring only bolt connections and hydraulic pipeline docking on-site, with an installation period of just 18 days (compared to the industry average of 30 days). During rainy days, temporary rainproof canopies protected equipment components to prevent corrosion. During commissioning, a 72-hour continuous full-load test simulated actual factory conditions (day/night temperature differences, wind effects), optimizing the stacker’s PLC program to achieve a stable stacking efficiency of 460 tons per hour. The truck unloader and feeder’s integration logic was synchronized to ensure precise matching of feeding and stacking capacities without interruptions or overloads.

Maintenance Training

ZOOMRY provided 15 days of specialized training for two factory maintenance personnel, covering daily inspections of open-pit equipment (roller rotation, hydraulic oil levels, dust cover sealing), common troubleshooting (belt misalignment, motor overload), and regular maintenance (roller lubrication, scraper replacement). The training addressed specific open-pit needs, including “rainy season drainage checks” and “winter hydraulic system preheating,” ensuring the maintenance team could independently operate and maintain the equipment post-training. ZOOMRY’s spare parts warehouse ensures delivery of common parts within 7 days, supported by a 24-hour multilingual technical hotline for lifelong technical support.

Project Outcomes

After commissioning, the system achieved stable long-term operation, exceeding expectations and resolving the factory’s core coal stockpiling challenges, delivering significant value. In terms of efficiency and capacity, the ZR120SF radial telescopic stacker achieved a stable 460 tons per hour, increasing the 54-meter stockpiling area’s inventory capacity to 85,000 tons, completely eliminating temporary transfers. The full process cycle from truck unloading to stacking was reduced from 4 hours to 1.8 hours, cutting annual downtime due to insufficient stockpiling capacity by approximately 35 hours, indirectly boosting production value. The integrated design of the truck unloader and feeder ensured precise matching of coal receiving and stacking capacities, eliminating unloading accumulation or stacker idling.

In terms of environmental and material utilization, the sealed system reduced dust emissions from 22 mg/m³ to 8 mg/m³, far exceeding national standards, eliminating complaints from surrounding areas and avoiding environmental penalties. The coal loss rate dropped from 5% to 0.8%, saving approximately 35,000 tons of coal annually based on a daily stockpile of 12,000 tons, significantly improving material utilization. The coal caking rate during the rainy season fell to 0.8%, eliminating the need for additional crushing processes and associated energy and labor costs.

In terms of reliability and open-pit durability, core components (rollers, pulleys, motors) maintained stable long-term operation, requiring only periodic belt and scraper replacements, reducing annual maintenance frequency from 12 to 4 times and cutting maintenance costs by 40%. The equipment achieved an annual failure rate of just 0.6% (well below the industry average of 1%), with no major failures due to extreme weather or rainwater. During a secondary factory capacity upgrade, minor adjustments to the stacker’s PLC program and motor power enabled adaptation to a new 500-ton-per-hour demand, demonstrating the equipment’s scalability and durability.

The factory project manager stated: “ZOOMRY’s stockpiling system not only resolved our efficiency and environmental challenges but also operates reliably in open-pit conditions. The equipment integration is seamless, and maintenance is straightforward. We will prioritize ZOOMRY’s solutions for future expansions.”

ZOOMRY Advantages

1. Diverse Product Line: Compared to single-equipment suppliers, ZOOMRY offers a full chain of “truck unloader + hopper feeder + radial telescopic stacker,” with precisely matched parameters, avoiding compatibility issues with different brands and ensuring seamless stockpiling.
2. Strong Adaptability: Leveraging its in-house R&D team, ZOOMRY optimizes equipment for specific conditions like open-pit slopes, temperature variations, and rainwater (e.g., 12° slope adaptation, hydraulic oil temperature control), reducing adaptation time by 50% compared to international brands.
3. Global Service Support: The equipment complies with ISO 9001, ISO 14001, CE, EAC, and other international certifications, meeting compliance requirements worldwide. Global spare parts warehouses and multilingual technical support address overseas clients’ challenges with slow spare parts delivery and communication, with response times far exceeding industry averages.