# Separation of Iron Oxide from Harbor Waste Using Selective Flocculation
## 2 Materials and Methods  
### Materials  
These tailings are stored in the Mineral Waste Processing Plant area in the Port of Constanta, Romania. Sampling is performed manually during the forming of the stockpile, with 100 samples taken, consisting of about 100 kg. This makes the sampling representative for the sludge; moreover, the company also performs chemical and physical analyses of the sludge as testing methods for the process' efficiency, and the results are comparable. After the mass is well mixed and homogenized, a representative sample of the mass of about 5 kg is separated. Representative sample of investigated \" harbor waste\" is handpicked and is labeled as sample \"K\" in this article.  
Since the starting raw material (\"harbor waste\"--sample K) is a mixture of different phases with a wide range of particle sizes, the sample is subjected to the sieving method to obtain three fractions of different particle sizes (K1, K2, and K3) and thus facilitates the analyzing process. Three classes are selected to determine the mass fraction of the largest (K1), medium-sized (K2), and smallest (K3) size classes. At the same time, the chemical composition of each class is determined individually. The fraction K1 consists of particles with a size of 450-250 \(\upmu\)m, the particles in fraction K2 are of 250-25 \(\upmu\)m in size, and particles in K3 are smaller than 25 \(\upmu\)m.  
After sieving sample K, which was previously dried in atmospheric conditions, the material of different fractions is treated with a hand-magnet. The use of a hand-permanent magnet on loose material is a simple standard manual procedure that can be used to separate ferromagnetic minerals.  
A magnet protected by cellophane is passed over the very surface of the material, which is scattered on paper, repeating the process until the ferromagnetic component is separated from the material.  
The magnetic fraction (marked with the suffix M) is roughly separated from the non-magnetic fraction at K1 and K2, while the smallest fraction is almost completely separated with a magnet. A total of 6 samples are obtained for SEM-EDS analysis, (K1, K1M, K2, K2M, K3, and K3M), of which 5 samples (K1, K1M, K2, K2M, and K3M) are analyzed using the X-ray powder diffraction method.  
All reagents used are of analytical grade, and they are prepared as solutions in distilled water.  
The 0.1% PAM A100 (anionic polyacrylamide--PAM-type SUPERFLOC A100, manufactured by Kemira, Helsinki, Finland) is used as flocculant. Preparation of flocculant for all experiments is carried out in the same way according to the instructions provided by the manufacturer of reagents [6]. As pH modifier, 0.1 M NaOH is used. Flocculant consumption is 250 g/t based on previous research [7].  
The 0.02 M SHMP (sodium hexametaphosphate, Na\({}_{6}\)P\({}_{6}\)O\({}_{18}\), manufactured by Lach-Ner, s.r.o. (Neratovice, Czech Republic)) is used as dispersant. The effect of dispersant on the stabilization of system is studied by conducting dispersion tests in 500 mL graduated glass cylinder.  
Dispersant consumption is 80 g/t, which, according to earlier research, is considered optimal [7].