AMF AMF Users Manual | Page 48

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• triphylite Li( Fe, M n) PO 4

• monazite( Ce, La, Y, Th) PO 4

• hinsdalite PbAl 3( P O 4)( SO 4)( OH) 6

• pyromorphite Pb 5( PO 4) 3 Cl

• vanadinite Pb 5( V O 4) 3 Cl

• erythrite Co 3( AsO

4) 2 · 8H 2 O

• amblygonite LiAlP O 4 F

• lazulite( Mg, Fe) Al

Process

2( PO 4) 2( OH) 2

The details below provide a list of phosphate minerals that will form insoluble precipitates

• wavellite Al 3( PO 4) 2( OH) 3 · 5H 2 O

• turquoise CuAl 6( PO 4) 4( OH) 8 · 5H 2 O

• autunite Ca( UO 2) 2( PO 4) 2 · 10-12H 2 O

• carnotite K 2( UO 2) 2( VO 4) 2 · 3H 2 O

• phosphophyllite Zn 2( F e, Mn)( PO 4) 2 • 4H 2 O

• struvite( NH 4) MgPO 4 · 6 H 2 O

• Xenotime-Y Y( PO 4)

• Apatite group Ca 5( PO 4) 3( F, Cl, OH)

• hydroxylapatite Ca 5( P O 4) 3 OH

• fluorapatite Ca 5( PO 4) 3 F

• chlorapatite Ca 5( PO 4)

3Cl

• bromapatite

• Mitridatite group:

• Arseniosideritemitridatite series( Ca 2( Fe 3 +) 3 [( O) 2 |( AsO 4) 3 ]· 3H 2 O--

Ca 2( Fe 3 +) 3 [( O) 2 |( PO 4) 3 ]· 3H 2 O) [ 1

]

• Arseniosideriterobertsite series( Ca 2( Fe 3 +) 3 [( O) 2 |( AsO 4) 3 ]· 3H 2 O-- Ca 3( Mn 3 +) 4 [( OH) 3 |( PO 4) 2 ] 2 · 3H 2 O) [ 2 ]

There are three approaches; ortho-phosphate is removed by forming an insoluble precipitate with Lanthanum, ferric, or magnesium. AFM ® is highly effective for this application because the precipitates formed are efficiently removed without solidifying the filtration bed.

1. The precipitating salts must be added via an aggressive static mixer, after the pump but before the filter 2. Lanthanum addition is stoichiometric at a molar ration of 1:1 3. Ferric addition should be at a ratio of 2-4 to 1 molar Ferric to Phosphate. This will give a surplus of ferric for coagulation and other flocculation reactions. The optimum concentration should be determined on a case-by-case basis because water with a high concentration of suspended solids, or other chemicals will influence the concentration of ferric required.

4. Struvite. The molar ratio NH3: Mg: PO4 equates with 1:8:3, this is not stoichiometric but it has been found in different water types to give good results. There will be a requirement to adjust the injection of magnesium to determine the optimum ratio.

5. The chemical reactions are rapid, and a period of 15 minutes is sufficient. Dryden Aqua air diffusers are designed to perform the mixing action. It is important to ensure that the dissolved oxygen concentration is above 2mg / l or the redox potential exceeds 300mv. Our air diffusers are easy to remove for cleaning and descaling.

6. Decantation may be required if the concentration of phosphate is above 5 mg / l as PO4-P, if not, it is a matter of just proceeding to AFM ® filtration

7. The AFM ® filtration process to remove the phosphate suspended solids will result in adsorption reactions of phosphate PO 4 2- directly onto the AFM ®.( N. B. An activated form of AFM ® designed to be even more selective with higher capacity for orthophosphate is in development.)