Omya in Vermont

Tailings Management

TAILINGS MANAGEMENT

On May 6, 2010 the Vermont Agency of Natural Resources (ANR) issued to Omya a five-year Solid Waste Disposal Facility Certification to manage its tailings in a lined, on-site Tailings Management Facility (TMF). The “Full” Certification issued by the ANR provides Omya with a long-term solution to managing its tailings operations in an engineered facility anticipated to be operational in late October, 2010.  Consistent with industry standards, the TMF includes an engineered polyethylene (plastic) geomembrane liner and leachate collection system.  The system will collect any water that may contact the tailings and recycle it back into the plant operations. 

While the TMF is under construction, Omya will continue to manage its tailings under the terms of the two-year Interim Certification issued by the ANR in October 2008.  The Interim Certification, in accordance with the Vermont Solid Waste Management Rules, allows Omya to manage its tailings on-site while at the same time systematically closing the existing unlined tailings management areas. 

To review the Full Certification and other related documents issued by the ANR, as well as the Act 250 Permit and related Findings of Fact issued for the TMF, click on the following links:  (NOTE: File sizes are large, and may take time to open or download)

05.06.10 Full Certification Cover (244KB).
05.06.10 Full Final Certification (159KB).
05.05.10 Final Omya Responsiveness (444KB).
06.02.10 ACT 250 Permit  (66MB).
06.02.10 ACT 250 Findings (86KB).

To review the complete Full Certification Application click on the following links:  (NOTE: File sizes are large, and may take time to open or download)

05.08.09 Full Certification Application Part A Administrative (8,000KB).
05.08.09 Part B Site Characterization (33,000KB).
05.08.09 Part C Engineering Design (40,000KB).
05.08.09 Part C-4 Engineering Drawings (17MB).
05.08.09 Part D Operational Information (904KB).

The following report was presented at an Environmental Stakeholder Meeting on June 30, 2009 by Sanborn Head & Associates.

06.30.09 Tailings Management Certification Application Presentation (8MB)

To review the complete Interim Certification click on the following link:

10.21.08 Interim Certification (780KB)

WHAT ARE TAILINGS PRODUCT?

Tailings are a by-product of Omya’s mineral processing operations, similar to many other mineral processing operations. The quarried marble feed stone contains mineral impurities, and the amount of these impurities must be reduced to satisfy customer requirements for calcium carbonate that is nearly pure. To do this, during processing, a flotation agent called TOHI (Tall Oil Hydroxyethyl Imidazoline – derived from Tall Oil, which itself is a by-product of the Kraft process of wood pulp manufacture from coniferous trees) is added to the process slurry along with air bubbles.  The mineral impurities (chlorite, plagioclase, feldspar, quartz, and mica) attach to the flotation agent and float to the surface with the bubbles. Because calcium carbonate is not attracted to the flotation agent, it does not float to the surface but rather settles to the bottom of the flotation tank and is collected for further processing. The mineral impurities are removed off the top, pumped to the Tailings Dewatering Facility and, once dewatered, are deposited into the tailing management areas in a form physically resembling moist sandy silt.

A tailings characterization study (192KB) confirms that the tailings are comprised almost entirely of natural minerals, including calcium carbonate that is not separated from the mineral impurities. The non-mineral components found in the tailings product are from the flotation agent added during the flotation process and are not present in quantities that cause harm to the environment or to human health.

HOW IS THE MATERIAL BEING MANAGED AT THE PLANT SITE?

Tailings product has been retained in Tailings Management Areas (TMAs) located at on-site quarry areas for over thirty years. The tailings product is maintained on site in order to be able either to find a market for it or to someday reclaim the 50% calcium carbonate remaining in the tailings product. To date, the technology has not been refined to enable broad-scale reclamation and re-use of the calcium carbonate content, nor has Omya yet been successful at its efforts to find large-scale beneficial uses for the tailings product.

In January 2009, Omya began operating a brand new Tailings Dewatering Facility (TDF) in order to achieve two primary goals:  1) improve on-site tailings management by mechanically recovering most of the associated process water and recycling it back to the plant, and 2) enhance tailings marketability by producing a byproduct with consistent moisture and particle size characteristics.  At a cost exceeding $10 million, the TDF is a good example of Omya’s commitment toward long-term efforts to improve environmental performance.

Economically viable markets for the tailings product are being sought actively, and technology to recapture and reduce the calcium carbonate content of the tailings product continues to be investigated.

IS THE MATERIAL SAFE?

Yes. Extensive scientific and technical investigations (192KB) confirm that the tailings do not produce an environmental or public health threat. Tests performed and supporting that conclusion have included tailings characterization, toxicological assessments, groundwater modeling, and geological surveying.

Only a very small percentage, a fraction of 1%, of the tailings product are composed of non-mineral substances, which include TOHI – the flotation agent used to separate pure calcium carbonate from the other minerals naturally occurring in the marble ore.

DOES OMYA TEST ITS TAILINGS PRODUCT?

Yes.  A tailing product characterization(192KB) was completed in June of 2005. Omya is publishing these tests here and invites you to review those tests to fully acquaint yourself with the results of that analysis.  In addition, Omya continuously evaluates the physical, mineralogical, and chemical characteristics of the tailings product.

HOW IS THIS MATERIAL REGULATED BY THE STATE?

Omya’s tailings product, and management thereof, has been regulated for over thirty years under Act 250. In addition, following the conclusion that the tailings product constitutes a solid waste requiring certification, on August 15, 2005, Omya filed an application with the Vermont Agency of Natural Resources for Interim Certification. The issuance of the Interim Certification allowed Omya to continue its operations for two years while alternative methods for management were pursued, along with continuing efforts to market the tailings product. The subsequent issuance of the “Full” Certification approved the use of the lined TMF for continued on-site management.

Omya has conducted, and will continue to perform, extensive analyses of the tailings management processes. To date, the studies demonstrate that the tailings product cause no harm to the environment or to public health.

HOW DOES OMYA PLAN TO REDUCE THE AMOUNT OF ITS TAILINGS PRODUCT?

Reduction of the volume of tailings product is an on-going goal. Since Omya began production at the Verpol plant in 1979, it has worked to improve ore management and its flotation process. These improvements have reduced the generation rate of tailings product and reduced the relative amount of process water used at the plant.

RELEVANT LINKS

Definitions

02.19.08 – Existing Tailings Management Areas Life Cycle Report (1.8MB)

08.15.05 – Tailings Characterization Report (192KB)

08.15.05 – Interim Certification Application (39.7MB).

Correspondence Related to the Interim Certification Application