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Sodium
Aluminate Powder Vs Sodium Aluminate Liquor
Sodium
aluminate liquor PW Grade (PW = Potable Water)
SODIUM ALUMINATE LIQUOR (PW Grade)
Sodium
aluminate liquor PW grade from Universal Chemicals is made from prime
materials to a consistent formulation which is generally known as 20/20.
Use is in the water,paper and chemical industries. This formulation was
developed by Universal Chemicals and is now a standard grade based on
nominal percentages of soda and alumina both a 20% by weight.
Universal Chemicals liquor is non-sedimentary and wholly inorganic in
content. It does not contain organic matter for example carbohydrates
deliberately added in order to stabilise the formulation and which form trace
haloforms or other organics in water.
All other liquid aluminates contain stabiliser. These are applied for various
reasons making the use of such aluminates prohibitive in water treatment and
doubtful in industrial applications such as papermaking where effluents are
generated.
Direct dosing of the liquor with flash mixing is recommended for simplicity of
operation.
Storage in unlagged tanks of mild steel or plastic constructions is
satisfactory. Freezing has not been experienced with the material in UK winter
conditions.
A note to all Water Authorities concerned with trends in potable water problems
and treatment.
Our work is concerned with current and potential development in the field of sodium
aluminate liquor.
Quality
This formulation was developed by Universal Chemicals and is now a standard
grade based on nominal percentages of soda (Na2O) and alumina (Al2O3)
both at 20% by weight.
Universal Chemicals liquor is non-sedimentary and wholey inorganic in content.
It does not contain organic matter for example carbohydrates
deliberately added in order to stabilise the formulation and which form trace
haloforms or other organics in water.
All other liquid aluminates contain stabiliser. These are applied for various
reasons making the use of such aluminates prohibitive in water treatment and
doubtful in industrial applications such as papermaking where effluents are
generated.
Direct dosing of the liquor with flash mixing is reccommended for simplicity of
operation.
Storage in unlaced tanks of mild steel or plastic construction is satisfactory.
Freezing has not been experienced with the material in UK winter conditions.
Technical Developments
In 1976 when ICI ceased manufacture of powder the users of aluminate were put
in doubt about supplies. the cost on alumina basis, relative to alum, was some
five times higher. This tended to detract from aluminates use.
ICI's withdrawal further reduced interest considerabl because of lack of supply
surety. The approach to aluminate in UK water treatment applications and
developments have consequently remained on the shelf.
The use in potable water treatment declined in consequence, during this period
when there have been discoveries concerning aluminates advantages. The downturn
in interest together with a dearth of research effort in the UK has meant no
practical plant investigations of the advances have been made.
Use in opposition to alum or ferric salts
Areas for investigation by the water treatment chemist usually involve the
application of aluminate in opposition to alum or ferric salts. Techniques are
varied according to circumstances.
Points of interest here are;
1. Flotation applications
The use of aluminate liquor in opposition to alum and feric salts reduces floc
density by up to 40% thereby increasing the flotation characteristics of the
floc.
The plant must be correctly designed and operated for reduced floc density to
be achieved by air entrapment in the floc forming process.
The mechanism is determined by correct design features, and the application of
flocculants at the right dosing point, to take advantage of opposition
applications.
2. Sedimenation
The reduction in floc density does not occur here as there is no high pressure
injection of air simultaneous with floc formation. Density of alum and ferric
salt flocs in pH dependant
pH control is facilitatedby the use of sodium aluminate the anionic character
of the aluminate ion 'buffering' the effect of the naturally occuring
inorganics. These can prevent steady pH control a difficult proposition when
lime or caustic salts are used to neutralise the pH depression produced by alum
or ferric salts.
The results in sedimentation plants are determined by the processes in the floc
blanket. There is little information on the nature of the mechanisms involved
in the feature. It is evident that the effectiveness of this important
filtration mechanism is determined by the conditioning of the floc before it enters
the blanket.
3. Virus removal by entrapment
Sheldon and Drewery examined the effect of various coagulants inorganic and
organic chemical combinations in the labratory. The Zinder strain (f2
bacteriophage) was selected to test effects. This work indicated the best
result was obtained by using aluminae in opposition to alum. The highest
removal of the virus - 99.89% was achieved with this formulation.
4. Residual metals in all waters
The minium levels of all metals including aluminium and iron are achieved by pH
control at around pH7.
Practical trials have shown that where alkalies such as caustic soda are used
to neutralise acid effluents heavey metal content is reduced by substituing
alkaline aluminate liquor for aprt of the neutralising alkali, usually caustic
soda or lime. Residual metals are reduced by a factor of 10. For example,
casutic soda only achieves around 10 ppm residuals. Application of aluminate
achieves levels below 1 ppm. Where pH control is not precise the use of
aluminate achieves even higher percentage reductions of residual metals.
Neutralisation of acid surface waters
The incidence of acidity and its degree s undoubtedly increaseing in surface
derived supplies. Stimultaneous breakdown of soil humus also occurs in these
cases. Sodium aluminate liquor will perform the dual function of neutralising
and flocculating in these cases.
Floc blankets
The use of aluminate in opposition to alum or ferric salts involves the same
considerations in terms of practical applications.
What is not known are the optimum conditions for realisation of optimum
performance.
Flocculation by alum or ferric has not recieved wide study particularly if the
character of flocculation blanket produced and its effect on the clarification
process. There are also aspects recently brought to the fore which have not
been quantified.
Sodium
Aluminate LiquorPW GRADE
HIGHEST QUALITY Potable water and pharmaceutical grade.
IRON FREE - NEAR WATER WHITE
INSTANTLY PROPORTIONABLE
LOW COST - STABLE SOLUTION
Concentrated sodium aluminate liquors of a high alumina content have not
been previously available in the UK. A liquid eliminates the health hazard of
dusty powders.
CHEMICAL
AND PHYSICAL PROPERTIES
Alumina - 20% by weight Al2O3
Soda - 20% by weight, Na2O
Density - 1.467
Quality
Commercial sodium aluminate liquors vary widely in their quality characteristics
and the suitability of the material for bulk reception and storage may depend
on this aspect.
Quality factors apply to the production of fine paper and high grade chemicals.
Universal Chemicals material is near water white quality and has very good flow
properties. The low level of material impurities in solution and suspension
means that it is colour free, and stable.
TREAT WATERS OF EFFLUENTS AND MAKE PAPER SAFELY & CLEANLY WITH ALUMINA
CHEMISTRY.
DOSE DIRECT FROM DRUMS OR BULK
TANKS
|
Viscosity/
Temperature C |
Viscosity
(typical)- Centipoise UNIVERSAL CHEMICALS |
Viscosity
(typical)- Centipoise COMPETITIVE |
|
10 |
275 |
858 |
|
20 |
180 |
440 |
Fluidity
In the feeding of systems by wither gravity or pump the viscosity data
indicates that Universal Liquor will give 21/2 to 3 times the supply rate.
Non - Sedimentary
The non-sedimentary nature of the liquor also reduces the need or tank and pipe
cleaning.
Method of Analysis
Details of these are provided for customers who wish to maintain their own
chemical control. Several methods are available.
Stability of Sodium Aluminate Liquors
These notes summarise a problem, which has been studied in detail by Universal
Chemicals both in the laboratory and during 2 years commercial use. The
following points are made to prevent misunderstandings by customers examining
samples, particularly those examining aluminate liquors for the first time.
1. The sample submitted is a NON-STABILISED material.
2. It has a storage time of about 12 months minimum in average summer
conditions in the UK. That is a maximum temperature of 25°C.
3. After 3 to 6 months, a small amount of solid may separate particularly at a
higher temperature. A hazy supernatant may develop simultaneously.
4. The supernatant liquor is still utilisable in this state as only about ½%
solids will have separated.
5. Storage under warmer conditions than 25°C may cause further accelerated precipitation.
Store tanks should be designed avoiding excessive heat or 'hot spots'.
6. The addition of water causes considerably increased rates of precipitation
usually after 24 hours. Solution prepared for precision tests should be used on
the same day.
7. USE NEAT AND PROTECT OUTDSIDE STORAGE TANKS FROM THE INGRESS OF RAINWATER TO
PREVENT PRECIPITATION.
8. DO NOT RINSE OUT TANKS OF ALUMINATE LIQUOR WITH WATER. RESIDUAL WATER WILL
CAUSE PRECIPITATES.
Approval tests should be completed within two months of receipt of samples.
Any queries regarding rapid analytical methods, stabilisation procedures and
other grade of material should be referred to Universal Chemicals.
Stabilised aluminates may be necessary where dilution is essential and details
can be supplied.