Salt: Cradle to GraveCatarina Hinojos

Race, Poverty and the Urban EnvironmentProfessor Raquel R. Pinderhughes

Urban Studies ProgramSan Francisco State University,

spring 2003

Public has permission to use the material herein, but only if author,

course, university and professor are credited.

This presentation focuses on the life cycle of Salt, cradle to grave, with emphasis on social, environmental

and public health impacts associated with it.

• The extraction process• Distribution of

materials needed to produce salt

• Distribution of salt• Health Impacts• And the waste

resulting from salt production

The Extraction Process of Salt

• Rock salt mining

• Solar salt mining

• Solution mining

• Vacuum Pan Salt Refining

There are four types of Extraction

Rock Salt Mining

• Rock salt mining occurs naturally in underground deposits

• Occasionally in surface deposits in arid areas, as the mineral halite

• Salt is physically dug out of the ground in an operation involving drilling, blasting, exploding and crushing the rock

Rock salt mine

Cargill.com

Rock salt mine

Cargill.com

Rock salt mine

dredge.com

Halite/rock salt

Saltinstitute.com

Rock salt beds/layers one meter thick

Saltinfo.com

A rock salt mine turned into a tourist attraction

Americanrocksalt.com

Solar Salt Mining

• Salt is produced by allowing the sun to evaporate sea water in shallow pools or ‘pans’.

• Both temperature and salinity are important • The water evaporates in successive ponds until

the brine is fully concentrated and salt crystallizes on the floor of the crystallizing ponds

dredge.com

                                          

Solar produced salt discolored by bacteria in the ponds nasalt.com

Solar salt pond with red brine

Salt-mine.com

The Alberger® brand salt is produced with the evaporating process alberger.com

This is an aerial view of salt ponds

Cargill.com

Great Salt Lake MineralsOgden, UtahSolar Pond Facility

Saltinfo.com

Solar salt mushrooms growing in the Dead Sea Salt.org

NATURAL SALT PRODUCTION OF SAN JACINTO

It is a realization of natural technical character practiced by dozens of residents of Charapoto community, in which the manual techniques of production of salt in the mineral

sources of San Jacinto are shown to the tourists Geocities.com

Solution Salt Mining

• When salt deposits are located fresh, recycled water is injected through a well drilled into an underground salt bed or salt dome

• Dissolution of the salt forms a cavern in the salt deposit

• Salt brine is withdrawn from the cavern and then transported by pipeline to an onsite evaporating plant to make dry salt, or to a chemical processing plant for chlor-alkali or other chemical production

Solution Salt scheme

Mininglife.com

This solution mining cavern, is where water is injected into a salt formation and brine is withdrawn kgs.ukans.edu

brine well and cavity

kgs.ukans.edu

Solution salt dome

Saltinstitute.com

Solution-Mined Cavern Storage

pbworld.com

Mineral Recovery

pbworld.com

Solution Mining Wellhead

Pbworld.com

Surface features at a West Texas disposal cavern 

npto.doe.gov

After salt is mined producers use caverns to store hydrocarbon substances, this is a map of them in Texas utexas.edu

Vacuum Pan Salt Refining

• Vacuum Pan Salt Refining produces table salt• Prior to mechanical evaporation, the brine may be

treated to remove minerals that can cause scaling in the evaporators and adversely affect salt purity

• Chemical treatment of the brine, followed by settling, reduces levels of dissolved calcium, magnesium and sulfate

• Sulfuric acid treatment or chlorination may be used to remove hydrogen sulfide, and hydrochloric acid will neutralize brine used in diaphragm cell production of chlorine and caustic soda

• Water is evaporated from purified brine using multiple-effect or vapor recompression evaporators

• Steam from boilers supplies heat evaporators and is fed from one evaporator to the next

• Vapor recompression forced-circulation evaporators consist of a crystallizer, compressor and vapor scrubber

• Feed brine enters the crystallizer vessel where salt is precipitated

• Vapor is withdrawn, scrubbed and compressed for reuse in the heater

Vacuum evaporator

Cargill.com

Saltinstitute.com

Saltinstitute.com

Lyons, KansasVacuum Salt Facility

Saltinfo.com

Distribution of Materials Needed to Produce Salt

• Salt is produced naturally in the environment so the only tools needed are for movement of the mineral – This includes pipes, conveyor belts, trucks,

roads, in some cases explosives

• And purifying agents for table salt– This includes boilers, chemicals and

evaporation equipment

Conveyor belt that transport salt to vehicle

Cargill.com

Underground vehicle that transports salt

Cargill.com

Underground salt mine

Cargill.com

Distribution of Salt

• Packages containing salt usually get transported by trucks

• Salt is used in three sectors– Deicing products

• melt ice and snow on roads– Commercial and industry

• manufacture chlorine, caustic soda and in paper making

– Domestic (table salt)

Mortonsalt.com

Deicing rock salt for snow and ice control

geo.msu.edu

Health Impacts

• Workers environments vary on what type of salt production they are involved with– But all employees are exposed to heavy

machinery– Some employees are exposed to explosives and

chemicals

• Consumers are also exposed to health hazards too much salt can cause illness– high blood pressure – heart attack – stroke

• When deicing salt is used on roads there tends to be a run off of water thus transporting salt into ground water– This causes a bitter taste in drinking water– The increase of salt in the soil isn’t good for

crops and natural vegetation

Miner digging for salt

Dredge.com

Saltinstitute.com

Waste Resulting from the Production of Salt

• The main waste that seems to be visible in all salt mines is the impact of heavy machinery on the landscape

• The waste from chemicals, explosives and trucks• Another factor is the destruction of natural

habitats to build unnatural salt ponds

Rods and wires nailed into natural caverns

Dredge.com

Web References

• www.utexas.edu• www.solutionmining.org• www.salt-mine.org• www.saltinstitute.com• www.saltinfo.com• www.mininglife.com

• www.mii.org• www.geo.msu.edu• www.cargill.com• www.americanrocksalt.com• www.npto.doe.gov• www.nasalt.com