Mesa Minerals Limited
Micro Nutrient Fertilizer

Mesa’s patented sulfur dioxide leach process is highly efficient and could be used to extract a very high percentage of the manganese in any given oxide ore irrespective of that ore’s grade. However, there are operational advantages, cost benefits and revenue gains to be achieved by decreasing the manganese ion recovery via the leach and allowing the unrecovered manganese units to report to the plant tailings.

Attaining these advantages is possible because the Mesa sulfur dioxide leach process effectively ‘preconditions’ the tailings leaving the majority of the metal ions present in a form suitable for slow release into soil via organic leaching. The tailings from an EMD or EMM plant using our leaching process will contain various elements required for stimulating healthy plant growth, in ratios dependent largely on the composition of the feedstock ore. However, in all instances the tailings will be rich in manganese ions, an element that is particularly deficient in Australian and Indian soils in many areas used for agriculture, which is somewhat ironic given the amount of manganese mined in these two countries.

Thus the interplay of Mesa’s multi nutrient fertilizer (MNF) patent and its manganese leach patent can be used to advantage of both new and existing manganese electrolytic plants that are or can be fed with manganese oxide ores. (NB: The technology could also be employed by an EMD or EMM plant that currently uses manganese carbonate ore, but could switch to a low cost oxide feed, with the carbonate ore redirected profitably into manganese alloy production for the steel industry.) In practice, many manganese electrolytic plants could switch to a low grade ore feed located much closer, which would cost far less to buy and ship to the plant.

The capital cost of replacing a roast circuit with a leach circuit and the provision of a new MNF circuit would be readily repaid out of increased revenues and lower costs. Plants undertaking such a retro-fitting would be effectively rejuvenated and could look forward to decades of additional life irrespective of the urbanization that inevitably intensifies around them. An additional bonus may also be possible where the old tailings dams can be reclaimed and the land reused or sold off.

The following example process flowsheet provides an overview of the steps in a joint EMD/MNF production plant:

A typical composition of an MNF product derived from a ferruginous 25% manganese oxide, sourced from Mesa’s Ant Hill mining lease as feed for an EMD plant, would be as follows:

  • Mn 9.4%
  • Fe 16.5%
  • Ca 10.8%
  • S 8.3%

These elements can be adjusted by either changing the ore grade input to the process or adding say additional manganese in the form of MnSO4 rendering the final specification ideal for application say in the manganese deficient agricultural areas of Western Australia. Customizing the product by the addition of elements such as zinc, copper and molybdenum is also a relatively easy and cheap task that would be performed prior to final product preparation. In most instances, Mesa would expect that the specification of the micro nutrient fertilizer product for any given ore source could be tweaked if necessary to match the requirements of the local area agricultural soil deficiencies. Where this is not the case, or a plant’s MNF production exceeds local demand, the excess production could be readily exported to other markets, due to the high demand for such products.

The form of the final MNF product would also depend firstly on the local area demand and then on export demand if necessary. An EMD or EMM plant using Mesa’s leach and fertilizer patents could produce a granulated product by first dewatering the tailings stream and then spray drying it, before utilizing either the agglomeration method or the compaction method to produce a granular product. In these cases, Mesa would ship the product to fertilizer companies for further blending and custom retailing in 1 tonne bulk bags.

Alternatively, a suspension concentrate could be produced by the addition of reagents and any additional elements required, with the product consigned in 20 litre drums, or larger fluids containers where required, ready for dilution before spraying.

Whilst the main argument for a new EMD or EMM plant adopting Mesa’s leach and fertilizer patents, or an existing plant retro-fitting them, is an economic one in that a significant cost is converted to a significant revenue, the environmental argument for doing so is also strong. Tailings impoundments are inherently big ugly expanding facilities that generate opposition in the communities surrounding them, and when their contents are not largely benign, as is the case where conventional roasting of manganese oxides or acid dissolution of manganese carbonates occurs, then this only serves to further stimulate opposition to tailings emplacement facilities in the local community. Mesa believes that the environmental argument alone would justify the retrofitting of its technologies to several of the existing alkaline EMD plants that are sited adjacent to residential communities, with the economic benefits coming as a bonus.

Click here for more information onĀ Mesa Minerals Products.