Proven technology for efficient grinding: High Pressure Grinding Rolls

The rotating side-plates improve the material feed into the rolls. By eliminating the so-called “edge effect”, the rotating side-plates ensure a more finely ground product and lower recirculation. Compared to conventional HPGR, this increases the throughput, while reducing the machine’s specific energy consumption. The rotating side-plates also result in a more uniform pressure profile and more even wear across the entire width of the rolls. This significantly increases the rollers’ roll service life.

The controlled mechanical skew limiter, a unique feature of the HPGR Pro, uses a mechanical locking device to limit misalignment of the movable roll. This allows the rolls to adjust to differing feed conditions. In this way, the more uniform pressure profile made created by the rotating side-plates is maintained across the width of the roll face and does not deform, as is the case with a skew suppressor.

This controlled skew limitation prevents critical values from being exceeded, protecting the rotating side-plates from damage… even in case of an emergency or operational error. The result is:

• Fewer machine outages and reduced downtimes.
• More uniform pressure profile.
• Increased safety and fewer shutdowns.
• Greater machine availability and reduced downtimes.
• Higher product quality.

Our unique laser stud detection system scans, measures and monitors the wear surfaces of rolls while in operation and the trending information is automatically stored. No more need to shut the HPGR down and access physically for taking manual measurements.

A local HMI panel is provided allowing maintenance personnel check the condition of the roll surfaces. The green/yellow/red color-coded “surface menu” displays the location(s) of possible defects on the roll surfaces.

• Defects are evaluated on the basis of different underlying parameters.
• Only relevant defects are reported.

The laser stud detection system not only detects missing or damaged studs and edge blocks but can help with scheduling roll change-out.

Lubricating the bearings with a constant flow of conditioned oil enables higher machine loads to be achieved. This also significantly lowers the operating temperature of the bearings and quickly removes any grit. All combine to maximize the service life of these critical components.

The oil is filtered and cleaned in a closed system, lowering lubricant consumption, which reduces operating costs as well as lowering the impact on the environment. 

The Advanced machine protection system (AMPS) constantly monitors the mechanical loads on the machine and warns the operator if specific loads are approaching the maximum allowed values, thus giving the operator the opportunity to react specifically, to reduce these loads.

Improved control systems as a prerequisite for further market driven automation – Operational Optimization!

• The data is processed in the integrated Siemens S7 1500 CPU and transferred, together with MCS and DCS e.g. via Profinet.
• If the alarm limits are superseded despite of the reaction of the operator, the Advanced machine protection system is giving an alarm to the process control system to stop the machine, to prevent a prolonged operation under overload.
• Generating load limit values and through automatically generated trends, analysis and reports.
• This feature increases the productivity of your plant - energy, feed, quality

In a HPGR the material is ground in the operating gap between to counter rotating rolls that are fed from above and a high pressure interparticle communication ensures a high product fineness.

The roll wear pattern will depend on the hardness and abrasiveness of the ore as well as the operating conditions and flowsheet configuration. Today roll lifetimes of about 8,000 – 20,000 h can be achieved in hard rock applications.

FLS is the leading supplier of HPGR`s with more than 160 units in Mining applications.

HPGR’s potential can be best realised when processing ores from either highly competent or highly variable deposits. The main reasons for selecting HPGRs over other technologies are their lower specific energy consumption, wear-material consumption, and reduced overall CO₂ footprint.

Therefore, even low-grade hard ores can be treated very economically. In addition, HPGRs produce a very uniform product, providing more stable plant throughput and better metal recovery. HPGRs are preferred for use in greenfield installations and brownfield expansions in tertiary or quaternary crushing stages, or as pebble crushers in semi-autogenous grinding (SAG)–ball mill circuits. They are also used as the final grinding step in producing the required iron-ore concentrate fineness for producing pellets.

These HPGR advantages, combined with continuous development and optimization of the roll wear-protection, have contributed to a rapid increase in the number of machines installed worldwide over the last 15 years.

HPGR and SAG mills use a different method of grinding. HPGR is a dry process grinding mill, while SAG mills are wet. SAG mills are a type of ball mill – a horizontal mill – whereas HPGR use rollers.