Economic growth and rapid urbanisation are driving the need for infrastructure. More roads, houses and power plants are needed, and for all that the world needs more minerals. Just the transition to renewable energy for electric cars and wind turbines requires more steel, copper, lithium and rare earth metals.
We need to produce these materials with the smallest negative impact to the environment as possible. The positive environmental impact of IPCC systems is enormous, with studies showing they can reduce GHG emissions by truly significant amounts, explains Branco Lalik – Director Mining Systems, FLSmidth.
There is, however, a more environmentally friendly alternative in material handling – In-Pit Crushing and Conveying (IPCC) systems. Mining companies are looking to cut their emissions due social pressure and regulatory threat and there is a growing need to implement environmentally sustainable handling systems and equipment.
Over the last decade they have started to establish IPCC systems on a large scale, substituting their truck fleets powered with fossil fuels stepwise with continuous material transportation on belt conveyors powered with electrical drives. The positive environmental impact of these systems is enormous, with studies showing they can reduce GHG emissions by more than 100,000 tonnes of CO2 per year (Norgate & Haque (2010), Energy and greenhouse gas impacts of mining and mineral processing operations. Referring to Carajas mine).
IPCC technology allows for reducing truck haulage in mines by moving the primary crusher from the processing plant closer to the mine for the crushing and conveying of Run-of-Mine (ROM) material. The operational efficiency can even be increased by entertaining relocatable or semi-mobile crushing stations, which can follow the mine progress keeping the truck transportation at a minimum possible level. Moreover, with a favourable mine layout a mine operation completely without mine trucks is possible with fully mobile crushing stations on crawler tracks operating directly with the shovel at the mine face.
Belt conveyors are much more energy efficient than trucks. While trucks use more than 60% of the energy to move themselves, belt conveyors are using on average more than 80% of the received energy to do what it is supposed to do – moving the mined material
Efficient belt conveyors – Proven technology in mining
Belt conveyors have been a proven technology in mining and materials handling for decades. They provide the highest efficiencies and lowest energy consumption compared to manually operated equipment.
Belt conveyors are much more energy efficient than trucks. While trucks use more than 60% of the energy to move themselves, belt conveyors are using on average more than 80% of the received energy to do what it is supposed to do – moving the mined material.
The ratio of moved material to total moved weight for a 360 st truck is almost 1:3, which means that the percentage of material moved is less than 40% on one round trip. An average overland conveyor with around 10,000 tph throughput and 1,000m length at belt speed 5 m/s makes up for more than 80% of material moved at a ratio of 1:1.2 of moved material to total moved weight without empty trips.
For many years FLSmidth has supplied and successfully implemented many overland belt conveyors in conventional troughed variant or as a closed tubular pipe conveyor. High-capacity conveyor systems of up to 20,000 tph operate in various commodities such as iron ore, copper or coal in South Africa, Peru, Brazil or Thailand.
The selection for IPCC with belt conveyors comes with a high degree of automation and digitalization. The growing drive towards the “Digital Mine” is another element quickening the implementation of IPCC systems. Mine operations with reduced or eliminated truck traffic make the application and standardisation of digital and date much easier.
Fully mobile crushing systems with a mobile crusher inside the pit and a downstream conveyor system to the plant or the waste area are the most efficient means of materials handling in open pit mines.
Fully mobile crushing systems – truck-less operation and cutting edge in mining systems
Semi-mobile primary crushing stations with the connected conveyor system is still the most used IPCC equipment being a mature technology working hand in hand with shovel and trucks. Recent FLSmidth installations in Brazil and India consist of a semi-mobile crushing plant and an overland conveyor system.
However, fully mobile crushing systems with a mobile crusher inside the pit and a downstream conveyor system to the plant or the waste area are the most efficient means of materials handling in open pit mines. These systems get along without trucks and provide the highest availability and productivity rates. But it is important to consider mine planning requirements such as the shape of the orebody and operational needs beforehand, as the fully mobile IPCC systems cannot be applied in every mine.
Vale’s S11D project with large scale fully mobile IPCC system has clearly been a cutting-edge operation and a milestone in Mining Systems. Four fully mobile crushing plants operate in ore and waste rock at the mine benches directly. They feed a combination of movable and relocatable series of conveyors and other material handling equipment in rates of several thousands of tons per hour. Lessons learned have shown that a full ramp-up to the targeted productivity figures can be reached after two to three years in operation.
The expected mine lifetime of 10 years and an hourly throughput of 2,000-3,000 tph should be the minimum when seriously considering IPCC on a larger scale for primary crushed material.
High availability and low total cost of ownership with IPCC Systems – not only for large scale operations
There are a couple of key performance indicators which help to pre-assess the economic feasibility of a fully-fledged IPCC system in a mine and support the early decision-making process. One of the key questions is “what is the right haulage balance to optimise OPEX?”
Continuous systems can become viable at truck distances starting at 2-4 km between the loading and unloading point. Further the handling capacity is essential to the equation. The expected mine lifetime of 10 years and an hourly throughput of 2,000-3,000 tph should be the minimum when seriously considering IPCC on a larger scale for primary crushed material.
Despite typically being more expensive upfront than truck fleets, the total cost of operation (TCO) for IPCC systems is normally favourable. A large reduction in OPEX through significantly less manpower, minimised maintenance and reduced fuel costs, coupled with high availability mean that these systems are a smart investment in the long term, often with a payback period of less than 3 years. IPCC systems also have a much longer life span than truck and shovel fleets, requiring fewer investments over their lifetime and, as a result, they are more suitable for long-life projects.
IPCC systems are competitive with mining trucks especially but not only for large scale operations on a sustainable and total cost basis – that should be interesting for the industry at large.