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Links found on this page -
aluminium ,
acid sulfate soils , blending reagents ,
by-product impurities , CRAB
Chemicals ,
Reagents & By-Product Impurities
Chemicals
Aluminium
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Aluminium is commonly found in
solution below pH 4.5 and is considered a product of Acid Sulphate Soils
usually a product of dissolved alugonite and kaolin clays. |
Aluminium Hydroxide
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Aluminium hydroxide is
dissolved aluminums when treated with calcium hydroxide in alkaline reagent
the products are called hydroxides. |
Arsenic
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Arsenic is one of the few
drinking water contaminants to be proven to cause cancer in humans.
Arsenic compounds exist through out the earth crust most often as |
Arsenic sulfide - AS²S³.
Metal arsenates - lead arsenate - Pb HA5O4
Potassium arsenite - KH²A²O4
Potassium arsentite - KA5 O²HA O²
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In water it
is likely to be present as a arsentite with an oxidation state of 5, if the
water is oxygenated in annoxic condition it will more likely be found as
arsentite oxidation rate of 3. |
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Arsenic is
introduced into the water ways by the dissolving and breaking down of rocks
and is pH related. An increase in pH may increase the presence of
dissolved arsenic in water. |
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Arsenic
sulfide is of interest to acid sulfate research. |
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Arsenic is sometimes
associated with coastal Acid Sulfate Soil sediments and has present a
significant long term poisoning problem. An example of this Stirling, a
suburb of Perth, Western Australia. |
Calcium Carbonate (CaCo³)
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CaCo³ is very
nearly the same weight as sulfuric acid. Calcium carbonate is 100 while
sulphuric acid is 98.
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The
alkaline/acid reaction is nearly 1:1 under laboratory conditions and in fact the
amount of acid available in a system is quite often described as Calcium
Carbonate equivalents, this does not necessarily mean that H²So4
is the only acid present, it means that it takes a certain amount of CaCo³
to neutralize a given amount of acid, however if H²So4 is the only acid present
in mg p/l.
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This can be
misleading depending on the efficiency, granular size and quality of the CaCo³.
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In many cases
outside of a laboratory efficiency of 10%-30% can be expected with field dosing
which can leave you wondering about the laboratory calcium carbonate
equivalents.
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Incidentally
the calibrating medium in the laboratory is sodium hydroxide ph 14.
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Calcium Limestone
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Calcium limestone is the product
of once submerged oceans with coral reefs made from CaCo³,
Calcium Carbonate.
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The reefs are
compressed by land fill and heat over millions of years to produce such things
as limestone and in some cases become a metamorphic rock known as marble, these
rocks when mined and crushed produce CaCo³.
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Calcium Oxide (CaO)
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Calcium Oxide is an extremely
reactive neutralizing agent and is produced by burning CaCo³.
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This drives
off the hydrogen and carbon atoms leaving a fairly unstable product.
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On
re-combining with water a vigorous exothermic reaction will occur.
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Chemical Spills
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In the event of accidental
spillage of pH related chemicals such as acids and alkalines eg Na(OH)²
and H²So4.
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The
CRAB can be used to provide accurate amounts of
reagent to deal with the problem.
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Cyanide
| Cyanide is sometimes used for the floatation process and dissolving
rock for the extraction of gold and copper and does present significant
danger to the environment. |
Hydrated Lime
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Hydrated Lime is stable
compared to other oxidized products such as Calcium Carbonate rock and creates
useful by-products, ie iron hydroxide. Hydrated Lime is naturally
forming substance as follows - |
Roasting CaCo³
releases O² leaving CaO - rehydrating CaO with H²O gives you Calcium Hydroxide
or Hydrated Lime.
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Hydrated Lime has a
neutralizing factor of 12.2 and is relatively inexpensive in relation to its
neutralizing efficiency. |
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Hydrated Lime is calibrated
easily with correct equipment, ie CRAB. |
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Sulfuric Acid (H²So4)
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Sulfuric
Acid is the main ingredient for discharge from oxidized sulfidic muds, eg iron
monosulfide and iron pyrites. |
Reagents
Blending Reagents
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The ability of the CRAB to
accurately blend reagents for a desired result.
CaCo³, calcium carbonate to attach and reduce metal loads and
Ca(OH²), calcium hydroxide to quickly and efficiently deal with acidity.
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A useful
product commonly known as 'slack lime' or burnt lime comes in two forms -
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1.
Calcium Hydroxide - pH neutralizing factor of 12.2
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2.
Calcium Oxide - pH neutralizing factor of 13.
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of the 2
Calcium Hydroxide is the more user friendly
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Brickies Lime
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Brickies lime is a useful
product commonly known as slack lime or burnt lime. |
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This lime comes in two forms - |
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Calcium hydroxide - pH neutralizing factor of 12.2
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Calcium Oxide - pH neutralizing factor of 13.
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Of the two Calcium Hydroxide
is the more user friendly. |
By-Product Impurities
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Gypsum or Calcium sulfate.
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Aluminium Hydroxide.
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Ferrous Hydroxides.
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Combination of micro species of
elements.
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Interestingly
these hydroxides that are produced act as a mop for other heavy metals and are
quite useful for this purpose in pH conditions above 5.4.
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Dissolved Minerals
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Most dissolved minerals are pH related so
therefore by manipulating pH dissolved metals at different pH levels.
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