Fraction_analysis_SOW_01252024_0002.pdf

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US Geological Survey

Alaska Science Center

Statement of Work

I. GENERAL INFORMATION

A. Introduction.

The U.S. Geological Survey, Alaska Science Center requests separation of heavy, middling, and light density fractions in four designated size fractions from ~150-pound (~70 kg) bulk samples of tailings collected from placer mines in Alaska, to yield two 200-gram splits per fraction for chemical and mineralogical analysis. There are 23 samples that will be processed.

B. Background.

The USGS has a mandate to assess resource potential for critical minerals needed for national security and the national economy that can be extracted within the US. The project requesting this service has a mandate to assess the potential of placer mine tailings in Alaska to contain critical minerals. A pilot study was conducted in collaboration with the US Bureau of Land

Management (BLM) and the Colorado School of Mines Kroll Institute for Extractive

Metallurgy to determine grain size and density parameters for identification of critical minerals in placer mine tailings. The size and density fractions requested in this document are defined by the results of this pilot study. The products of this processing, the 200-gram splits, are necessary for acquiring the chemical and mineralogical analyses needed to determine the resource potential of the placer mine tailings. The USGS has no laboratories that have the appropriate equipment or personnel to perform this service.

C. Definitions/Applicable Documents

Size fractions of unconsolidated sediments are acquired by sieving at specified mesh sizes that are measured in fractions of inches, millimeters, and/or microns.

Tails: light density fraction of an unconsolidated sediment sample

Middling: middle density fraction of an unconsolidated sediment sample

Concentrate: heavy density fraction of an unconsolidated sediment sample

These density fractions can be acquired by several different types of laboratory gravity separation instruments.

D. Scope.

The objective of the service requested is to obtain 400 grams of each of 10 fractions of a 150-pound sample of unconsolidated sediment, divided into 2 splits – one for geochemical analysis, and one for mineralogical analysis. The entire 150 pounds of sediment will need to be processed in order to obtain the 200-gram splits. It is possible that some samples will not yield enough material to achieve 400 grams in each fraction. Therefore, in addition to the need for quality control and avoidance of contamination of samples, it is mandatory that the samples be processed efficiently and meticulously.

II. WORK REQUIREMENTS

A. Technical Requirements.

1. Describe specific work requirements and/or work products.

The USGS requires samples that are composed of unconsolidated sediment from placer mine tailings that need to be separated into size and density fractions. These samples consist of

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~150 pounds (~68kg) of sediment at a grain size of less than or equal to 6 mm. The entire sample must be processed in order to obtain splits of the appropriate size and weight for chemical and mineralogical analysis. The samples need to be separated in to 4 size fractions, classified by screening at 10 mesh (2 mm), 30 mesh (0.6 mm), and 100 mesh (0.15 mm); each size fraction must be separated into tails, middling, and concentrate density fractions. It is recognized that a middling fraction may not be achievable for the coarsest size fraction, (-

6.0mm/+2.0mm). The resulting 12 fractions each need to yield 2 splits as close to 200 grams as possible, in a secure (safe from breakage or contamination) medium and returned to USGS

PI at the Alaska Science Center or as otherwise specified by USGS PI. A log of the sample separation process and chain of custody signed and dated by the laboratory technician is required for each sample for QA/QC. The two 200-gram splits are needed for chemical and mineralogical analysis to determine the distribution and quantity of critical minerals that have mineral resource potential for each sample. Excess material from each sample can be discarded.

2. Criteria for acceptance of Product or Service.

The quality of the contractor’s services will be measured by inspection of logbook records that must accompany the sample processing, and inspection of the sample splits that will be delivered to the project lead scientist at the Alaska Science Center. There are no test samples available to supply to the contractor.

B. Deliverables.

1. Characteristics for work product described in II.A.1., identified by name and quantity.

The 10 fractions from each bulk sample must yield 2 splits as close to 200 grams as possible, in a secure (safe from breakage or contamination) container (vial or polyethylene bag) and returned to USGS PI at the Alaska Science Center or other specified location. A log of the sample separation process and chain of custody, signed and dated by the laboratory technician, is required for each sample for QA/QC.

2. Delivery dates for work/product to be completed and point of delivery.

3. Option to possibly exercise at a later date at additional cost, subject to cost and funding availability: chemical analyses that can identify elements from the splits obtained in the separation process explained above; element list attached.

4. Option to possibly exercise at a later date at additional cost, subject to cost and funding availability: mineral identification of the middling and concentrate splits obtained in the separation process described above.

5. If options 3 and 4 are pursued, any remainders from the 200 gram splits after analyses will be mailed to the PI at the Alaska Science Center.

III. SUPPORTING INFORMATION

A. Place of Performance. Contractor’s facility

B. Period of Performance. Approximately five months from the date of award.

Splits should be delivered to the USGS within 16 weeks of receipt of samples.

C. Government Furnished Property (GFP): list property and its value. N/A

D. Special Considerations.

1. Key personnel qualifications. Lab technicians are trained and qualified to operate the instruments employed in sample processing.

2. Data Rights, Safety, Environment. N/A, no analyses will be performed on site.

3. Security/Privacy issues (ingress to Federal buildings, personnel clearances, computer security). N/A

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U.S. Geological Survey 2022 list of Critical Minerals Aluminum Antimony Arsenic Barite Beryllium Bismuth Cerium Cesium Chromium Cobalt Dysprosium Erbium Europium Fluorspar Gadolinium Gallium Germanium Graphite Hafnium Holmium Indium Iridium Lanthanum Lithium Lutetium Magnesium Manganese Neodymium Nickel Niobium Palladium Platinum Praseodymium Rhodium Rubidium Ruthenium Samarium Scandium Tantalum Tellurium Terbium Thulium Tin Titanium Tungsten Vanadium Ytterbium Yttrium Zinc Zirconium