Руководство по крепежу для горного оборудования: критичес...

The most common causes of rock bolt failure: corrosion — in wet African underground environments, especially where water has high acidity (common in copper/cobalt mines in DRC and Zambia), black steel bolts can corrode significantly within 2-3 years; specify hot-dip galvanized or epoxy-coated bolts. Incorrect installation — resin bolts require correct mixing and installation procedure; if the resin cartridge is expired or incorrectly mixed, bond strength is inadequate. Stress corrosion cracking — in high-stress zones, bolts can crack; use appropriate bolt grade and consider fiber-reinforced polymer (FRP) bolts for highly corrosive environments. Vibration-induced loosening — mechanical anchors can loosen under seismic activity or blast vibration; use face plates and systematic support spacing.

In high-abrasion iron ore applications in South Africa and Zambia, traditional bolted screen systems typically last 2-4 weeks before requiring replacement. Bolts fatigue, threads wear, and holes elongate due to abrasion. Quick-release sidebar/wedge systems last 4-8 weeks with faster change-out times. For operations targeting high uptime, investment in premium sidebar systems (Metso, Schenck, or equivalent) often pays for itself through reduced downtime.

Slurry pipelines (common in African iron ore and copper operations) require: Flange bolts — heavy hex bolts Grade 8.8 or 10.9, sized to match the flange rating (ANSI Class 150/300/600 or PN16/PN25); use flat washers under both head and nut. Corrosion allowance — specify HDG or epoxy coating; for acidic slurries (pH < 5), specify stainless steel 316 or duplex stainless flanges and bolts. Thread sealant — use PTFE tape or liquid thread sealant on all threaded connections to prevent leakage. Abrasion protection — specify wear-resistant pipe with thick-wall construction; flange bolts should be long enough to accommodate any future internal lining.