Scrapers in Reversible Conveyors: Restoring Reliability in a Critical Coke Transfer Line

Overview

A high-capacity reversible conveyor on a coke transfer line was experiencing recurring carryback and spillage, forcing frequent cleanups, unplanned downtime, and safety risks. Multiple legacy scrapers had been tried without success. Hosch deployed a next-generation Scraper System engineered for reversing motion to eliminate carryback at the source and stabilize operations.

The Challenge

• Heavy spillage below the snub pulley and along return idlers.
• Unplanned shutdowns for cleaning and maintenance activities.
• High manual cleaning effort.
• High service frequency frequency of existing scrapers with limited results.
• Previous trials with scrapers from alternative suppliers failed to deliver the desired results.

Root Cause Analysis

Hosch technical audits revealed that the installed scrapers, designed with 90° vertical blade contact with the belt, failed to achieve desired cleaning efficiency.This configuration:

• Lacked an effective reversing mechanism, compromising cleaning in reverse motions.
• Suffered continuous vibration due to lower pulling stability, lowering cleaning efficiency.
• Needed high contact pressure for optimum performance, accelerating belt wear and shortening belt life.
• Required frequent manual adjustment, leading to high manpower involvement for maintenance activities.

Solution Architecture

Hosch recommended and implemented a dual-scraper configuration designed specifically for reversible conveyors:

Main Scraper — B6C-REA

• Reversible-duty main scraper with tungsten carbide tip blade designed for reversing belts installed under the belt.
• Reversing mechanism provides an additional turning point: blades gently turn forward and downward during reverse, maintaining light, controlled contact on the back side of blade tips.
• Self-adjusting mechanism reduces manual intervention and suppresses vibration.

Pre Scraper — HDPUL

• Installed at the 3 o’clock position on both discharge pulleys to address bidirectional flow.
• 3rd-generation segmented PU blades for uniform pressure, consistent cleaning and lower maintenance cost.

Operations Context (Application)

The conveyor transfers screened coke to stock bins feeding the furnace—an uptime-critical link. Persistent carryback spillage below snub pulleys and return idlers was disrupting throughput and elevating safety exposure around the line.

Results & KPIs

Maintenance & Cleaning

• Scraper servicing interval extended from once in every 20 days to once in every 45 days
• Spillage cleaning frequency reduced from once in every week to once in a month.
• Cleaning manpower requirement dropped from ~90 mandays/year to ~9 mandays/year.

Downtime & Safety

• Production shutdowns reduced from ~20 hrs/month to ~3 hrs/month.
• Carryback accumulation reduced from ~12 m³/month to ~1 m³/month.
• A cleaner environment reduced safety risk for personnel.

Before vs After (At a Glance)

Why It Worked

Special features of the B6C scraper that enhance cleaning efficiency:

• Z-type blades with angular contact: This inclined design works against the belt travel, scraping off material effectively while applying minimal pressure on the belt.
• Reduced vibration: Achieved through higher Pulling Stability.
• Elastomount auto adjustment system: Mounted at both ends, it allows automatic adjustment for blade wear, ensuring consistent belt contact.
• Independent blade segments: Each spring-mounted segment deflects individually, preventing belt damage and maximizing cleaning efficiency.

Business Impact

The upgrade converted an intervention-heavy conveyor into a stable, low-touch asset—freeing maintenance bandwidth, reclaiming production time, and lifting safety standards around the line. The case demonstrates how reversible-duty scraper engineering delivers measurable reliability in coke handling.

Key Takeaway

Eliminate carryback at the source with scraper systems designed for reversing motion. The right geometry, tensioning, and reverse-mode kinematics translate directly into fewer cleanups, longer service intervals, and safer, more predictable operations.

Call to Action

Looking to cut carryback and downtime on a reversing belt? Talk to our conveyor specialists about a site audit and a reversible-duty scraper configuration tailored to your application