Long-Distance Limestone Conveying Solution

An open-pit factory focuses on limestone mining and processing operations, with core material being limestone (particle size 5-30mm, moisture content 6%-9%, high hardness and prone to dust generation). It needs to build a dedicated conveying line from the limestone mine crushing area to the factory's raw material yard, achieving seamless integration of the entire "mining-crushing-conveying-storage" process. Previously, the factory used a hybrid mode of "belt conveyor+truck transfer": the 3200-meter conveying route, due to the presence of 3 natural bends, required ordinary belt conveyors to set up 2 transfer stations, which not only increased equipment investment but also led to a limestone loss rate of 4.5% due to transfer loading and unloading; a single ordinary conveyor had a handling capacity of only 1800 tons/hour, unable to match the factory's 2200 tons/hour crushing capacity, causing limestone accumulation in the crushing area during peak periods; the open design of transfer links and truck transportation resulted in dust emissions of 25mg/m³, far exceeding the 10mg/m³ limit in the "Comprehensive Emission Standard of Air Pollutants", leading to frequent complaints from surrounding areas; meanwhile, ordinary conveyors could not adapt to a 12-meter elevation gain, requiring additional ramp platforms and increasing civil construction costs; core equipment components relied on external procurement, with spare parts response cycle exceeding 30 days and annual downtime over 80 hours, resulting in low maintenance efficiency.

ZOOMRY, combining on-site survey data from the factory (terrain curve distribution, limestone characteristics, meteorological records), designed a full-chain solution with "long-distance curve belt conveyor as the core, supplemented by truck unloader and hopper feeder", forming a closed-loop system of "limestone receiving-uniform feeding-curve conveying".

Project Overview

Core Requirements

In terms of parameter requirements, the core conveying equipment needs to meet a handling capacity ≥2200 tons/hour, belt width 1200mm, conveying length 3200 meters, adapting to 3 horizontal curves (turning radius ≥600 meters, maximum turning angle ≤60°), elevation gain of 12 meters, and featuring sealed dust prevention; in terms of scenario adaptation, the equipment must withstand open-air high temperatures (40℃), low temperatures (-8℃), and rainwater environments, with core components (rollers, motors) having protection level ≥IP55; in terms of compliance, dust emissions ≤10mg/m³, equipment conforming to CEMA standards and domestic environmental regulations; in terms of maintenance, core components (rollers, drums) service life ≥50,000 hours, providing global spare parts response and multi-language operation training to ensure the maintenance team can operate independently.

Core Objectives

Based on the requirements, the project sets four major goals: first, efficiency compliance, with the conveying system handling capacity stable at ≥2200 tons/hour, full 3200-meter route without transfers, completely replacing the transfer mode; second, environmental compliance, dust emissions controlled within 8mg/m³, limestone loss rate reduced to below 1%; third, terrain adaptation, equipment smoothly adapting to 3 horizontal curves and 12-meter elevation without additional transfers or site modifications; fourth, maintenance optimization, equipment annual failure rate ≤0.6%, global spare parts response ≤7 days, reducing annual maintenance costs by 30% compared to traditional modes.

Solution Design

Core Equipment

For the 3200-meter curve route, 2200 tons/hour handling capacity, and 12-meter elevation requirements, ZOOMRY custom-produced 1 set of long-distance curve belt conveyor, optimized for open-air limestone conveying:

• Curve and elevation adaptation design: adopting "multi-segment curve coordination + gradient tension control" technology, adapting to 3 horizontal curves (turning radius 600 meters, maximum turning angle 57°), through "self-aligning roller group + flexible belt guiding" structure, preventing limestone spillage at turns—the roller group uses ZOOMRY's self-developed self-aligning rollers (diameter 133mm, suitable for 1200mm belt width), radial runout ≤0.4mm (better than national standard 0.5mm), automatically correcting belt deviation, 72-hour immersion test water ingress ≤95g (better than ZOOMRY standard 100g), adapting to open-air humid environments; for 12-meter elevation, adopting "gradient slope design" (average slope 0.375%), coordinated with ST2500 steel cord conveyor belt (tensile strength ≥2500N/mm, wear-resistant layer thickness 12mm), ensuring no belt slippage during heavy-load elevation, and the belt's overlapping seal structure (overlap 120mm) further blocks dust escape.
• Power and efficiency assurance: adopting "head triple drive" design, equipped with 3 units of 220kW variable frequency motors (total power 660kW, protection level IP55), paired with hardened gear reducer (transmission efficiency ≥96%), enabling real-time speed adjustment based on limestone conveying volume to avoid overload; belt speed set at 3.5m/s, linked with PLC feeding system to regulate feed rate, ensuring stable handling capacity of 2200 tons/hour; drive drums use 40Cr forged material (diameter 500mm), diamond-pattern rubber lagging surface (friction coefficient ≥0.4),经过 ultrasonic testing and stress relief tempering, no internal cracks, service life over 50,000 hours, meeting the wear demands of heavy-load limestone conveying.
• Open-air durability enhancement: conveyor frame uses hot-dip galvanizing process (anti-corrosion level reaching Zn12 grade in GB/T 13912-2002), adapting to open-air rainwater and moisture corrosion; removable transparent PC rain cover installed above the conveyor belt, facilitating inspection while shielding from rain and sun exposure, preventing belt aging; hydraulic tensioning device equipped with oil temperature control system, stable operation in -8℃~40℃ temperature range, automatically compensating for belt thermal expansion and contraction, ensuring stable belt tension in curve and elevation sections.

Auxiliary Equipment

To ensure seamless connection of limestone from mine transport vehicles to the conveyor, the solution includes two types of ZOOMRY self-developed equipment, with parameters precisely matching the core conveyor:

• ZRLS-TU1400 wheeled truck unloader: installed in the limestone receiving area, belt width 1400mm, handling capacity 200-1000 tons/hour, suitable for the factory's commonly used 40-ton dump trucks. The equipment features 2 hydraulically adjustable ramps (slope 6.7°), allowing trucks to drive directly onto unloading without reversing, with double-layer rubber sealing skirts at ramp bottoms to reduce dust escape during unloading; also equipped with vibration feeder to real-time adjust unloading speed based on conveyor operation status, preventing limestone accumulation in the receiving area and achieving "unloading-conveying" rhythm matching.
• ZR series hopper feeder: installed between unloader and conveyor, using 10cbm standard receiving hopper (optional larger capacity), equipped with 18.5kW variable frequency speed-regulating motor, real-time adjusting feed rate (1800-2200 tons/hour), ensuring uniform limestone flow into the conveyor, avoiding overload or underload; hopper inner walls lined with 12mm thick wear-resistant ceramic liners to cope with high hardness abrasion of limestone, top installed with dust hood to reduce dust dispersion and rainwater entry in open-air environments, preventing limestone from getting damp and caking.

Core Components

All key components are independently produced by ZOOMRY, with performance superior to national standards and CEMA standards, providing support for long-term stable system operation:

• Rollers and drums: in addition to curve section self-aligning rollers, straight sections use quiet rollers (diameter 133mm), rotation resistance ≤2N (better than national standard 3N), operating noise ≤45dB (better than national standard 55dB), 72-hour immersion test water ingress ≤95g, adapting to open-air humid environments; besides drive drums, redirecting drums use 40Cr seamless steel pipe material (diameter 400mm), surface thermal sprayed with wear-resistant coating, abrasion resistance improved by 50%, ovality <1.5mm, ensuring smooth belt operation.
• Cleaning and safety components: conveyor head and tail each equipped with 1 set of PU material cleaning scrapers, with ≥98% adhesion to conveyor belt, effectively removing residual limestone particles, avoiding belt deviation caused by material adhesion; also equipped with "double safety protection"—belt deviation switch (automatic alarm when deviation >5mm) and emergency rope break system (shutdown within 0.01 seconds upon steel wire rope breakage), conforming to international safety standards; unloading end fitted with non-powered dust suppression chute (built-in airflow buffer chamber), further reducing unloading dust.

Project Implementation

Preliminary Survey

ZOOMRY dispatched a 6-person technical team to the open-pit factory, spending 12 days on three key tasks: using total station and drone to map the 3D terrain of the 3200-meter route, precisely marking the center positions of 3 horizontal curves, turning radii, and slope distribution of the 12-meter elevation section, optimizing conveyor frame installation height to avoid rainy season water accumulation areas; collecting limestone samples for laboratory testing of flowability, abrasiveness, and moisture content to determine key parameters such as roller spacing (1.2 meters) and belt tension (18kN); based on local meteorological data (high/low temperatures, rainy season distribution), formulating specialized open-air protection schemes, such as rain cover installation positions and hydraulic oil temperature control parameter settings.

Manufacturing

All equipment and components are produced at ZOOMRY's Hebei factory, fully incorporated into ISO 9001 quality management system and ISO 14001 environmental management system: long-distance curve belt conveyor drive drums must pass 24-hour static load test at 1.2 times rated load without deformation to qualify; rollers undergo 1000-hour no-load operation test to verify sealing and rotation resistance; ST2500 conveyor belts complete tensile, wear, and bending tests before factory shipment. Factory representatives conducted acceptance at the plant, all parameters meeting contract requirements, especially outstanding results in open-air durability tests (high-low temperature cycling, rain exposure testing).

Installation and Commissioning

ZOOMRY dispatched a 10-person installation team to the site, adopting "modular splicing + phased commissioning" mode: dividing the 3200-meter conveyor into 16 segments (200 meters each), pre-assembled at the factory in advance, requiring only bolt connections and belt vulcanization on-site, with installation cycle of only 30 days (industry average 45 days); during rainy weather in installation, temporary rain shelters covered equipment components to prevent rainwater corrosion; commissioning phase in three steps—single equipment no-load test (verifying motor and roller operation status), system linkage test (unloader-feeder-conveyor coordination), 72-hour full-load trial operation (simulating actual open-air conditions like high temperature and curve conveying), optimizing PLC program to stabilize conveyor handling capacity at 2250 tons/hour, exceeding the 2200 tons/hour requirement.

Maintenance Training

Providing 15 days of specialized training for 8 factory maintenance personnel, covering daily inspections of open-air equipment (roller rotation status, hydraulic oil level, rain cover sealing), common fault handling (belt deviation, motor overload), and periodic maintenance (roller lubrication, scraper replacement); training uses multi-language operation manuals (Chinese, English), with additional skills for open-air environment specifics such as "rainy season equipment drainage inspection" and "winter hydraulic system preheating", ensuring the maintenance team can independently handle equipment operation and basic maintenance after training. Common spare parts response time ≤7 days, 24-hour multi-language technical hotline, lifetime technical support.

Project Achievements

After commissioning, the project has been running stably long-term, with all indicators exceeding expectations. In terms of efficiency and capacity release, the full 3200-meter no-transfer conveying design enables the conveyor to stably handle 2250 tons/hour, fully matching the factory's 2200 tons/hour crushing capacity, eliminating limestone accumulation during peak periods; conveying cycle shortened from 5 hours in traditional "conveyor + truck transfer" mode to 1.4 hours, reducing annual production downtime due to insufficient conveying by about 45 hours, indirectly enhancing capacity value, while smooth adaptation to 3 horizontal curves eliminates the need for additional transfer stations, further saving related equipment and civil construction investments.

From environmental and material utilization perspectives, the full-system sealed design effectively controls dust emissions, reducing from 25mg/m³ to 7.2mg/m³, far exceeding national standards, with no more surrounding complaints to the factory and completely avoiding environmental penalty risks; limestone loss rate dropped from 4.5% to 0.8%, with annual conveying volume of 18 million tons saving about 666,000 tons of losses annually, significantly improving material utilization; plus rain cover and sealed belt design, rainy season limestone caking rate reduced from 12% to 1.5%, eliminating additional crushing processes, saving energy consumption and labor costs.

In terms of reliability and open-air durability, core equipment components (rollers, drums, motors) operated over 35,000 hours without large-scale replacement, requiring only periodic belt changes and scraper cleaning, annual maintenance frequency reduced from 10 to 3 times, maintenance costs down 40%; even in -8℃~40℃ open-air environment, equipment annual failure rate only 0.4%, far below the 0.6% target, with no major failures due to extreme weather or rainwater; later during factory's secondary capacity upgrade, only minor adjustments to motor power and PLC program accommodated the new 2500 tons/hour demand, with equipment scalability and durability fully exceeding expectations.

The factory project leader stated: "The biggest headache back then was conveying the 3 curves and 12-meter elevation. ZOOMRY's equipment not only handles curves very smoothly but also keeps up with the crushing rhythm. Over these years of open-air wind and rain, the equipment never failed us. Last time we urgently needed to replace a roller, the technician guided us remotely and we replaced it ourselves without delaying production. Now we're planning a new limestone processing line and will definitely prioritize ZOOMRY again, as the equipment we've used is reliable and the service is solid."

ZOOMRY's Core Advantages

1. Customized curve adaptation capability: International brands require over 6 months design cycle for multi-curve long-distance conveying, ZOOMRY relies on self-developed "curve tension control technology" to complete full solution customization in just 2.5 months, with adaptation precision and operational stability of the 3 horizontal curves far exceeding industry averages, avoiding drawbacks of traditional transfer modes.
2. Full-chain equipment coordination advantage: Providing full-process equipment of "truck unloader + hopper feeder + curve belt conveyor", with precise parameter matching among equipment (e.g., unloader discharge speed coordinated with feeder feed rate), avoiding compatibility issues of different brand equipment; core components self-produced, with performance indicators of rollers and drums superior to national standards and CEMA standards, ensuring overall system reliability.
3. International compliance and service system: Equipment conforms to ISO 9001, ISO 14001, CE, EAC and other international certifications, meeting compliance requirements of different global regions; multi-language technical support resolves overseas clients' pain points of "slow spare parts and difficult communication", with maintenance response speed far exceeding industry averages, aligning with ZOOMRY's "global customer service" positioning.