Fluorosilicic Acid Supply Chain - Executive Summary

Fluorosilicic Acid

Direct Use Chemical

H2SiF6
(liquid)

Inputs to Manufacturing Process:
Phosphate Rock
Sulfuric Acid

J* Derivative Water Treatment Chemicals:
*

None

% of Total Domestic Consumption
Attributed to Water Sector:
Approximately 63%

Understanding Chemical Supply Chains
Map of Suppliers & Manufacturers

A. Product Family:

u

Phosphate

CAS No.:
16961-83-4

2 Shelf Life:
1 Month

 RISK OF SUPPLY DISRUPTION (Assessed in 2022)

RISK RATING: Moderate-Low

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RISK DRIVERS

Production of fluorosilicic acid
depends on the production of
phosphate rock and manufactur-
ing of sulfuric acid. Planned fa-
cility downtime at the limited
number of domestic manufac-
turing facilities has resulted in
recurring volatility in the supply
of fluorosilicic acid.

RISK PARAMETERS

Criticality: Low. Used widely but in
discretionary application.

Likelihood: High. Previous
widespread disruptions in supply
that impacted the water sector.

Vulnerability: Moderate-High. Lim-
ited domestic manufacturing con-
centrated in select geographic areas
and strong reliance on imports.

MANUFACTURING PROCESS

Water Treatment Applications

Phosphate Rock

Sulfuric Acid

Fluorosilicic Acid

Input

End Use

Fluoridation of drinking water

Other Applications

	Production of metal fluorosilicates

	Masonry and ceramic hardening

	Solar panel and chip production

DOMESTIC PRODUCTION AND CONSUMPTION, AND INTERNATIONAL TRADE

Domestic Manufacturing Locations (2017):

5, in Florida, North Carolina, Louisiana,
and Wyoming

(S* International Trade (2019)

Primary Trading Partner (Imports): China
Primary Trading Partner (Exports): China

Domestic Consumption (2019):

58 M kg

	Domestic Production (29 M kg)

	Imports for Consumption (39 M kg)

	Export of Domestic Production (10 M kg)

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Fluorosilicic Acid Supply Chain - Full Profile

Product Description

Fluorosilicic acid (FSA) (H2SiF6), a halogenated inorganic acid, is the water fluoridation compound most widely
used in community water systems in the U.S. as it yields free fluoride rapidly when mixed with water. The
majority of FSA produced is used for municipal water fluoridation, and the remainder is mostly consumed by the
aluminum industry to produce aluminum fluoride.

Use in Water Treatment

FSA is used in water treatment for drinking water fluoridation (AWWA, 2011).

Use as a Precursor to Other Water Treatment Chemicals
None.

Other Applications

FSA is used in aluminum fluoride and other metal fluorosilicate manufacturing, hardening masonry and
ceramics, metal surface treatment, and solar panel and silicon chip production. It is also used in hydrofluoric
acid production (ATSDR, 2003; USGS, 2020a).

Primary Industrial Consumers

Water fluoridation is the primary use of FSA. In 2001, it is estimated that approximately 63% of FSA was
consumed for water fluoridation (ATSDR, 2003).

Manufacturing, Transport, & Storage

Manufacturing Process

Production of FSA for water fluoridation takes place as a byproduct of the reaction to produce wet-process
phosphoric acid. The majority of phosphate rock, represented in Figure 1 as fluorapatite (Ca5(P04)3F), contains
approximately 3-4% fluoride. The primary reaction, which involves digestion of phosphate rock with sulfuric acid
to produce phosphoric acid, is shown in Figure 1. During this reaction, sulfuric acid reacts with other elements in
phosphate rock and through these reactions fluoride and silicon are mobilized to form silicon tetrafluoride and
hydrogen fluoride, as shown in the secondary reaction in Figure 1. The hydrogen fluoride and silicon
tetrafluoride vapors can be recovered through filtration and evaporation. When the gases are scrubbed with
water, FSA is formed as a waste stream (Solvay, 2013). FSA is not a discrete compound, but rather an aqueous
mixture of fluorosilicated compounds (AWWA, 2011).

Primary Reaction



Phosphate Rock + Sulfuric Acid > Phosphoric Acid + Gypsum +

Hydrogen Fluoride

Cas(P04)3F + 5H2SO4 > 3H3PO4 + 5CaS04 +

HF

Secondary Reaction (Gas Capture)



Silicon Tetrafluoride + Hydrogen Fluoride > Fluorosilicic Acid



Si F4 + 2HF > H2SiFs



Figure 1. Chemical Equation for the Reaction to Manufacture Fluorosilicic Acid

EPA 817-F-22-028 | December 2022

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Fluorosilicic Acid Supply Chain - Full Profile

Product Transport

FSA is considered a strong, corrosive acid, but is commonly transported by rail and tanker truck (OxyChem,
2018). Given the limited number of domestic production facilities which are concentrated in Florida, Louisiana,
North Carolina and Wyoming, long-distance transport may be required to deliver FSA throughout the U.S.

Storage and Shelf Life

FSA should be stored in cool, well-ventilated areas and under these conditions has a shelf life of one month. It is
highly corrosive, and exposure to strong oxidizers or elevated temperatures can lead to the release of hydrogen
fluoride and hydrogen gas through decomposition (Simplot, 2021; Solvay, 2013).

Domestic Production & Consumption

Domestic Production

Production data was collected from the U.S. Geological Survey (USGS), while trade data was collected from the
U.S. International Trade Commission (USITC) Dataweb, as shown in Table 1. While production data is specific to
fluorosilicic acid, trade data represents import and export of inorganic acids, 'not elsewhere specified' (NES).

Table 1. FSA Production and Trade Data Sources

Production and Trade Data

Category

Data Source

Identifier

Description

Domestic Production

U.S. Geological Survey

2019 Fluorspar Data Sheet1
CAS No.: 16961-83-4

Fluorosilicic Acid

Imports and Exports

International Trade
Statistics
U.S. International
Trade Commission

HS Code: 2811.19
HTS Code: 2811.19.60

Inorganic Acids Other than
Hydrogen Fluoride
Inorganic acids, NES

Total U.S. domestic production of FSA from phosphate rock was approximately 29 million kilograms (M kg) in
2019 (USGS, 2021). The vast majority of domestic commercial manufacture of FSA is integrated with
manufacturing of phosphoric acid from phosphate rock (USGS, 2020a). Domestic commercial manufacturing of
FSA as a co-product of phosphoric acid production has historically taken place in Florida, Louisiana, North
Carolina, and Wyoming by J.R. Simplot, Mosaic Company, and PCS Phosphate Company (USGS, 2020a). The
number of domestic manufacturing locations has fluctuated between 2010 and 2019, varying between four and
six facilities. The number of domestic manufacturing locations shown in Figure 2 represents operating facilities
as of 2017 (USGS, 2020a). Supply of NSF/ANSI Standard 60 certified fluorosilicic acid for use in drinking water
treatment is widely distributed throughout the U.S. (NSF International, 2021). For a more current listing of
manufacturing locations and supplier locations, visit the U.S. Environmental Protection Agency's (EPA's)
Chemical Locator Tool (EPA. 2022a).

1FSA production, as sourced from phosphate rock, is included in the USGS profile for fluorspar (U.S. Geological Survey. 2020. 2017
Minerals Yearbook: Fluorspar, https://www.usgs.gov/centers/national-minerals-information-center/fluorspar-statistics-and-
information)

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Fluorosilicic Acid Supply Chain - Full Profile

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Domestic Supply and Manufacturing of Fluorosilicic Acid
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Figure 2. Domestic Supply and Manufacturing of Fluorosilicic Acid

Domestic Consumption

U.S. consumption of FSA in 2019 is estimated at 58 M kg. This estimate includes production of 29 M kg, import
of 39 M kg, minus export of 10 M kg (USGS, 2021; USITC, 2021), as shown in Figure 3. Imports and exports
represent trade of inorganic acids, NES (HTS Code 2811.19.61), while production data is specific to FSA.

Domestic Consumption (2019):

58 M kg

	Domestic Production (29 M kg)

	Imports for Consumption (39 M kg)

~ Export of Domestic Production (10 M kg)

Figure 3. Domestic Production and Consumption of Fluorosilicic Acid in 2019

Trade & Tariffs
Worldwide Trade

Worldwide import and export data for FSA is reported through the World Bank's World Integrated Trade
Solutions (WITS) software, as a category representing a class of inorganic acids other than hydrogen fluoride. In

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Fluorosilicic Acid Supply Chain - Full Profile

2021, the U.S. ranked ninth worldwide in total exports and fourth in total imports of inorganic acids other than
hydrogen fluoride. In 2021, China ranked first worldwide in total exports and total imports (WITS, 2022), as
shown in Table 2. Import and export data specific to FSA is unavailable from the referenced sources.

Table 2. WITS Worldwide Export and Import of Inorganic Acids Other than Hydrogen Fluoride, including Fluorosilicic
Acid, in 2021

2021 Worldwide Trade
Inorganic Acids Other than Hydrogen Fluoride (HS Code 2811.19)

Top 5 Worldwide Exporters

Top 5 Worldwide Importers

China

92 M kg

China

71 M kg

Israel

40 M kg

Sweden

67 M kg

Poland

27 M kg

Germany

33 M kg

Germany

15 M kg

United States

31 M kg

Malaysia

14 M kg

Brazil

17 M kg

Domestic Imports and Exports

Domestic imports and export data are reported by USITC in categories for inorganic acids, NES. Figure 4
summarizes imports for consumption2 and domestic exports3 between 2015 and 2020. During this period, the
overall quantity of exports and imports remained relatively steady, with imports for consumption exceeding
domestic exports. Over this five-year period, China was the primary recipient of domestic exports and the
primary source of imports (USITC, 2021).

Domestic Trade of Other Inorganic Acids, NES

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Figure 4. USITC Domestic Import and Export of Inorganic Acids, NES, including Fluorosilicic Acid, between 2015 and
2020

2	Imports for consumption are a subset of general imports, representing the total amount cleared through customs and entering
consumption channels, not anticipated to be reshipped to foreign points, but may include some reexports.

3	Domestic exports are a subset of total exports, representing export of domestic merchandise which are produced or manufactured in
the U.S. and commodities of foreign origin which have been changed in the U.S.

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Fluorosilicic Acid Supply Chain - Full Profile

Tariffs

There is a 4.2% general duty for import of FSA, and an additional 25% duty on imports from China (USITC, 2022),
as summarized in Table 3.

Table 3. 2020 Domestic Tariff Schedule for Inorganic Acids, NES, including Fluorosilicic Acid

HS Code

General Duty

Additional Duty-China
(Section 301 Tariff List)

Special Duty

2811.19.61

4.2%

25%

Free (A, AU, BH, CA, CL, CO, D, E, IL, JO, KR,
MA, MX, OM, P, PA, PE, SG)4

Market History & Risk Evaluation

History of Shortages

As noted, FSA is most commonly produced by capturing and processing the offgas from the wet method of
phosphoric acid production. Flowever, the infrastructure necessary to capture and process the offgas is not
present at all phosphoric acid manufacturing locations, both domestic and worldwide. Disruptions in the supply
chains for phosphate rock and phosphoric acid at the facilities that can capture and process the offgas can
therefore have a significant impact on availability of FSA.

Phosphate rock is mined in large quantity in a limited number of countries worldwide. In 2017, Morocco, China,
and the United States were the leading producers of phosphate rock (USGS, 2020b). The Hubei Province of
China, which experienced a prolonged lockdown in 2020 due to the COVID-19 pandemic, is the location of 30%
of the country's phosphate production. Similar supply chain disruptions, impacting shipping and transport
activities have occurred elsewhere. Though the supply shocks resulting from COVID-19 lockdowns appear to
have been temporary, other supply challenges to the phosphate rock market were ongoing in 2022.

In 2020, Mosaic, a leading domestic manufacturer of phosphate-based products, petitioned the US Department
of Commerce to investigate alleged unfair government subsidies of phosphate fertilizers produced by Russia and
Morocco. Mosaic alleged the unfair subsidies increased prices for phosphate in the US, which affected the prices
of phosphate-based products such as phosphoric acid. Initial action in 2020 by the Department of Commerce led
to a shift in trade flow and an increase in the domestic price for phosphate, a trend that continued through 2021
(INN, 2021).

The American Water Works Association (AWWA) released a memo in 2012 remarking on ongoing shortages of
FSA supplied to water utilities. AWWA noted that FSA shortages were cyclical and typically seen after June, and
recommended utilities ensure full storage by June each year and prepare for increased lead times during
warmer months (AWWA, 2012).

4 Symbols used to designate the various preference programs and trade agreements. A full list of special trade agreements and
associated acronyms can be found at https://help.cbp.eov/s/article/Article-310?laneuaee=en US and the General Notes Section of the
Harmonized Tariff Schedule https://hts.usitc.eov/current

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Fluorosilicic Acid Supply Chain - Full Profile

Risk Evaluation

The complete risk evaluation methodology is described in Understanding Water Treatment Chemical Supply
Chains and the Risk of Disruptions (EPA, 2022b). The risk rating is calculated as the product of the following three
risk parameters:

Risk = Criticality x Likelihood x Vulnerability
Criticality	Measure of the importance of a chemical to the water sector

Likelihood Measure of the probability that the chemical will experience a supply disruption in the
future, which is estimated based on past occurrence of supply disruptions

Vulnerability Measure of the market dynamics that make a chemical market more or less resilient to
supply disruptions

The individual parameter rating is based on evaluation of one or more attributes of the chemical or its supply
chain. The ratings and drivers for these three risk parameters are shown below in Table 4.

Table 4. Supply Chain Risk Evaluation for Fluorosilicic Acid

Risk Parameter Ratings and Drivers



1 1



1 Criticality Low

1 Likelihood High 1

[Vulnerability Moderate-High 1

FSA has widespread but discretionary
application for fluoridation and is not
used as a precursor to manufacture
other water treatment chemicals.

The water sector has experienced
widespread FSA supply disruptions in
the past. FSA is produced at a small
number of facilities concentrated in
Florida and Louisiana. The facilities
that produce FSA as a byproduct of
phosphoric acid production routinely
experience periods of planned
downtime, which results in recurring
volatility in the supply of FSA.

Limited domestic manufacturing
concentrated in select geographic
areas, strong reliance on imports with
high tariffs, and limited shelf life lead
to an elevated vulnerability. The lack
of considerable competing uses for
FSA slightly reduces the vulnerability.

Risk Rating: Moderate-Low

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Fluorosilicic Acid Supply Chain - Full Profile

References

Agency for Toxic Substances and Disease Registry (ATSDR), 2003. Toxicological Profile for Fluorides,

Hydrogen Fluoride, and Fluorine, retrieved from https://www.atsdr.cdc.gov/toxprofiles/tpll.pdf

American Water Works Association (AWWA), 2011. B703 Fluorosilicic Acid. Denver, CO: American Water
Works Association.

American Waterworks Association (AWWA), 2012. Fluoridation Chemicals (memo). Denver, CO: American
Water Works Association.

EPA, 2022a. Chemical Suppliers and Manufacturers Locator Tool, retrieved from

https://www.epa.gov/waterutilitvresponse/chemical-suppliers-and-manufacturers-locator-tool

EPA, 2022b. Understanding Water Treatment Chemical Supply Chains and the Risk of Disruptions, retrieved
from https://www.epa.gov/waterutilitvresponse/risk-disruptions-supplv-water-treatment-chemicals

Investing New Network (INN), 2021. 'Phosphate Outlook 2021: Price Rally Expected to Continue', retrieved
from https://investingnews.com/dailv/resource-investing/agriculture-investing/phosphate-
investing/phosphate-outlook/

NSF International, 2021. Search for NSF Certified Drinking Water Treatment Chemicals, retrieved from
https://info.nsf.org/Certified/PwsChemicals/

Potash Corporation of Saskatchewan, Inc. (PotashCorp), 2015. Form 10-K2014, retrieved from
https://www.sec.gov/Archives/edgar/data/855931/000119312515062Q91/d863198dl0k.htm

Simplot. 2021. Fluorosilicic Acid Safety Data Sheet, retrieved from
http://sds.simplot.com/datasheets/17200.pdf

Solvay, 2013. Product Safety Summary: Fluorosilicic Acid, retrieved from

https://www.solvav.eom/sites/g/files/srpend221/files/2021-01/PSS-Fluorosilicic-Acid.pdf

U.S. Geological Survey (USGS), 2020a. 2017 Minerals Yearbook: Fluorspar, retrieved from

https://www.usgs.gov/centers/national-minerals-information-center/fluorspar-statistics-and-
information

U.S. Geological Survey (USGS), 2020b. 2017 Minerals Yearbook: Phosphate Rock, retrieved from

https://www.usgs.gov/centers/national-minerals-information-center/phosphate-rock-statistics-and-
information

U.S. Geological Survey (USGS), 2021. Mineral commodity Summaries for Fluorspar, retrieved from
https://www.usgs.gov/centers/national-minerals-information-center/fluorspar-statistics-and-
information

U.S. International Trade Commission (USITC), 2021. USITC DataWeb, retrieved from
https://dataweb.usitc.gov/

U.S. International Trade Commission (USITC), 2022. Harmonized Tariff Schedule (HTS) Search, retrieved from
https://hts.usitc.gov/current

World Integrated Trade Solutions (WITS), 2022. Trade Statistics by Product (HS 6-digit), retrieved from
https://wits.worldbank.org/trade/countrv-bvhs6product.aspx?lang=en#void

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