Summary

Chatham Rock Phosphate (CRP) aims to be the premier supplier of direct application phosphate to the New Zealand and global agricultural sector, supporting sustainable farming and agricultural processes. To realize this objective phosphate will be mined at the 400 meter deep Chatham Rise, located in the SW South Pacific Ocean. Chatham Rock Phosphate’s failure to get an environmental consent for marine mining in New Zealand is one example of the increasing global need to develop validated tools and methodologies to predict, adaptively manage and reduce the environmental effects of marine mining.

Objective

A final goal is to improve our knowledge and predictive capabilities of both the plume dispersion and the continuous process of settling, deposition, consolidation and associated shear strength development of tailings, and what effect the use of flocculants might have on this.

Methodology

The study comprises 3 phases, each comprising a number of analyses.

Phase 1: laboratory analyses of mine tailing behaviour

1. Collation of typical tailing samples for further laboratory analyses (2016/2017)
2. Accurate determination of sediment settling velocities
3. Settling and consolidation columns

Phase 2: laboratory analyses to assess the effect flocculants on tailing behaviour

1. Selection of flocculants legal for use in New Zealand
2. Determination of optimal flocculants dosage
3. Assess operational parameters affecting flocculants performance
4. Accurate determination of settling velocities
5. Settling and consolidation columns.

Phase 3: modelling

1. 1DV modelling (with and without flocculants)
2. Reporting; elaboration of results in a set of guidelines.

The majority of the work will be executed in 2017. Pending approval it is aimed for to start the first activity before the end of 2016.

Decisions on the details of the implementation of phase 2 and 3 will be based on the results of phase 1.

Expected project results

The main project results are:

1. A set of prototype guidelines and lessons learned on:
   1. Validating the critical sediment parameters required to predict mine tailing (sediment) plume dispersion without a need for trial mining.
   2. Assessing the feasibility and effectiveness of the use of flocculants as a measure in an adaptive mining strategy.
2. Results of how the guideline works for the Chatham Rise project.

Although these guidelines will be developed in the context of the Chatham deep sea mining project, they will be useful in the much broader context of marine mining and dredging for marine infrastructure development. This implies that, besides relevant for the TKI Delta Technology, the envisaged results of this project are also relevant for the TKI ‘Maritiem - Winnen op zee’. In case of positive results, it is likely that the PPS will be continued (see also ‘valorisation’).