Annelie Lundström introduces a novel core scanner for geochemistry, images, structures, specific gravity, volume bulk density and more
Minalyzer CS is a scanner that, in a contactless and non-destructive way, generates geochemistry, high-resolution images, rock quality designation (RQD), structures, specific gravity and bulk density for drill cores, drill cuttings and other drill samples.
The patented scanner is designed for handling large volumes of drill samples and is capable of scanning drill cores directly in core trays. A laser (LiDAR) generates a 3D-model of the topology of the core and trays, which enables the control and precision of the continuous XRF scanning. RQD and structures are also be derived based on the 3D model.
The objective, continuous and consistent nature of the datasets as well as the high but compact data density generated by the scanning technology is paramount in machine learning and deep learning applications as well as approaches to geology. Machine learning and deep learning have been demonstrated to be effectively used, based on the data from the scanning, for prediction of host rock lithologies.
A cloud-based software for visualisation and generation of datasets through digital tools facilitates remote access to a digital version of the drill sample. Remote access to data has become critical to keep project and operations moving forward when travel has become impossible and/or risky due to the pandemic.
The bulk density can be derived based on measured volume from LiDAR scan of the Minalyzer CS, combined with the weight of the core tray. The method is suitable for friable sediment core where a true representation of the friable or heavily fractured sample through manual measurements and estimates can be error prone. The new method has been tested and applied in live applications by iron ore companies in Western Australia where extensive comparisons between the new method and the traditional have been made. The method has also been tested on known volumes and densities for verification and demonstrate both a high level of repeatability and accuracy. Other benefits with the method are that it can be automated to a high degree and provides a non-subjective measurement. Due to its implementation the bulk density value derived would represent a conservative measurement of the bulk density.
Minalyzer CS case study
A real-world case study demonstrates the results that this approach is enabling companies to achieve. The Rönnbäcken nickel project is located in northern Sweden, and was until recently explored by Nickel Mountain Group. Drill cores from Rönnbäcken were analysed with Minalyzer CS.
“Minalyze’s technology represents a significant advance in quick geochemistry to support the exploration geologist in her or his endeavours to find deposits viable for mining,” says Johan Sjöberg, Chief Geologist at Nickel Mountain Group. “The technology enables you to effortlessly have geochemical data at your fingertips when logging drill core, without the hassle of re-logging the core after sampling and assay at a conventional lab.”
The Rönnbäcken project is an ophiolite-hosted metamorphogenic nickel sulphide deposit, which consists of serpentinised ultramafic lenses that host a measured and indicated resource of 668.3 Mt with an average grade of 0.176 % nickel, of which 0.099 % is nickel sulphide. Nickel sulphide minerals include pentlandite, heazlewoodite and millerite.
The contact zones of the deposit are commonly enriched in arsenic, hosting minerals such as gersdorffite, orcelite and nickeline. Arsenic is a troublesome element that is commonly found alongside commodities such as copper, cobalt, nickel and gold. Due to environmental restrictions, smelters give penalties for ore concentrates that contain significant amounts of arsenic and reject concentrates with more than 0.5 % arsenic. Arsenic minerals can induce crippling penalties at the smelter, if they are not well characterised and kept out of the nickel sulphide concentrate.
To illustrate the accuracy of the scanning results, they were compared to conventional laboratory assays. The scanning results were reported on a higher resolution than the conventional assay intervals. “Another great advantage is the improved resolution. At Rönnbäcken we typically assayed in 2m intervals: with Minalyze we can get a resolution that is less than a hundredth of that,” says Sjöberg. “We can actually look at the composition of a vein or alteration band right off the bat.”
The results from drill core scanning with Minalyzer CS not only provide an accurate estimation of the total nickel content but can also indicate arsenic-rich zones in the mineralisation. Awareness of penalty elements at an early stage allows geologists to take them into consideration during the whole process of resource characterisation.
Annelie Lundström is CEO of Minalyze