Overhead clearance restrictions limit the vertical dimensions of sampling equipment that could be installed at an Australian gold mine. Accordingly, McLanahan designed a system with an ultra-low profile.

McLanahan Corp. recently tailored one of their falling stream sampler designs to meet the needs of a gold mining application in Western Australia. 

According to the Pennsylvania, USA-based company, the Australian mine processes 1,000 metric tons per hour (mt/h) of gold ore through high pressure grinding rolls (HPGRs), which tend to create a flaky product. To achieve a more cubical product, the mine had McLanahan add a DDC-Sizer to the process, along with a sampling system for collecting samples of DDC-Sizer discharge being sent to the agglomerator.

“Overhead clearances were pretty tight for the project, so we had to stay within a certain vertical clearance
so we could fit within the project envelope,” explained Adam Orner, product manager for sampling systems at McLanahan.

In addition to height limitations, the primary sampler also had to fit the outlet of the DDC-Sizer. Following these specifications, McLanahan designed a two-stage sampling system consisting of a primary and a secondary, horizontal carriage bottom dump sampler.

“The horizontal carriage arrangement gives you the best low-profile setup that you could possibly achieve with a falling stream machine,” Orner said. 

A secondary, horizontal carriage bottom dump sampler will take a sample of the increment collected by the primary sampler.  

A McLanahan secondary horizontal carriage bottom dump sampler takes its own samples from material delivered to it by a vibratory feeder from an upstream primary sampler.

Horizontal carriage bottom dump samplers are a type of falling stream sampling system. They collect sample increments by passing a cutter through a material stream as it falls from a machine or conveyor belt to another machine or conveyor belt.

With the horizontal carriage arrangement, the cutter is oriented to the side of the drive carriage. As the chain drive moves the carriage from one end of the machine to the other and back, the cutter moves back and forth through the falling material flow to collect the sample. When the cutter reaches the discharge end, the door located on the bottom of the cutter opens to release the sample material.

“Horizontal carriage bottom dump samplers can handle pretty much any type of material,” Orner said. “They are very adaptable and very well-suited for a variety of materials.”

For this application, the primary sampler extracts sample increments from the DDC-Sizer product stream and discharges them on to a vibratory feeder. The sample material is then delivered to the secondary sampler with a controlled feed. Final samples are removed from the vibratory feeder flow by the secondary sampler and delivered to a four-station rotary sampler collector. The reject material from the secondary sampler is discharged into the agglomerator feed chute and reintroduced into the process flow.

“Ultimately, we’re going to help them collect representative primary samples and secondary samples so that they can take those samples back to the lab to process them to develop good data for making decisions with their process,” Orner said.