Overview

Mn Battery Minerals Pty Ltd is planning to become a globally significant producer of High Purity Manganese Sulphate Monohydrate (HPMSM) used in the manufacture of electric vehicle batteries. The company was established following the acquisition by the parent company (Resource Development Group) of the Ant Hill and Sunday Hill manganese tenements near Marble Bar in the Pilbara region of Western Australia. Following the successful production of HPMSM, the company aims to develop a production facility at Boodarie, approximately 20km from Port Hedland, which will be capable of producing 100,000tpa of HPMSM.

Background

In March 2020 Resource Development Group Limited announced it was acquiring 100% interest in manganese tenements at Ant Hill and Sunday Hill from Mineral Resources Ltd.

MnBM Tenement Map

Progress

Since acquiring the two manganese assets, the Company has progressed the project on multiple fronts, including:

  • Significant progress in putting in place all of the required approvals and permits.
  • Geometallurgical assessment of the orebodies underway.
  • Metallurgical test work continuing.
  • Design of the pilot plant nearing finalisation.
  • Mine Planning & Logistics models being developed.
  • Continued positive engagement with vehicle and battery manufacturers.
  • Land access, Boodarie (proposed location of future HPMSM process plant).

Metallurgical Test Work

The initial test work program commenced in January 2023 with an aim of producing High Purity Manganese Sulphate Monohydrate (HPMSM). A sample was made by combining ore-grade material from seven diamond drill holes from Ant Hill (Diamond drill hole locations shown below) into a single composite.

The chemical composition of the composite is shown in Table 1. This composite is higher in manganese than the average of the overall deposit but is thought to better represent beneficiated ore due to the low silica grade.

Ant Hill Deposit

Production of Manganese Sulphate

Test work was undertaken to develop a flowsheet for the production of HPMSM from Ant Hill ore. The work reported here is from the initial proof-of-concept runs with further process development underway.

The composite was ground to a nominal P80 of 250µm prior to leaching. A subsample of ground composite was reductively leached to produce a solution containing >100g/L Mn, <10g/L Fe, <5g/L Al, <4g/L K and <2g/L Na, all other impurities were below 1g/L. The solution contained low concentrations of both Co (>350ppm) and Cu (>250ppm). The recovery of manganese into solution has consistently been >95.0%. The leach residue consists primarily of Fe and Si.

The solution was purified using a novel multistage precipitation process to remove K, Na, Fe, Si and Al prior to initial filtration. The filtrate was then sulphided to remove the base metals, notably Co and Cu, which were filtered to produce a high-Co sulphide. A further stage of purification removed the majority of Ca and Mg which were filtered and combined with the ferrous precipitates and leach residue. These purification stages reduced the impurity metal contents to sufficiently low levels for the production of HPMSM.

The purified solution was evaporated to crystallise high purity manganese sulphate which was then recovered and dried to produce a solid phase.

Table 1: Composition of composite used in the test work

Table 1: Composition of the composite used in the test work

Table 2: Dual analyses of the HPMSM samples produced in Runs 5 and 6.

Table 2. Dual analyses of the HPMSM samples produced in Runs 5 and 6.

Table 2 shows the analyses of the HPMSM products from two independent runs using the composite in Table 1. The flowsheet used was largely the same, but with operational changes to each stage to optimise the different stages. After evaporation, the crystals were thermally dried at 105°C and sent for analysis.

The deliquescence of manganese sulphate monohydrate (32.8%Mn) results in it adsorbing water from the atmosphere to form the pentahydrate, (22.8%Mn) thus any delay between sampling and analysis results in a lower concentration of elements. To overcome this, the measured Mn concentration in the sample is multiplied by a factor to give 32.0%Mn, the same factor was used to scale the impurities.