Cleaning Contaminated Sediments by Separation on the Basis of Particle Size

1993 ◽  
Vol 28 (8-9) ◽  
pp. 283-295 ◽  
Author(s):  
C. van Rijt
Keyword(s):  
Particle Size ◽  
Froth Flotation ◽  
Fine Fraction ◽  
Contaminated Sediments ◽  
Selective Separation ◽  
Sand Fraction ◽  
Silt Fraction ◽  
Positive Effects ◽  
Recent Developments ◽  
Clean Contaminated

In the Netherlands large quantities of contaminated sediment have to be dredged. Because it cannot be relocated directly in the marine environment, the dredged material must be placed in special contained depots which are expensive to construct. In 1989 a programme to reduce the volume of storage space required was started. This paper includes the results of research into the physical aspects of sediment cleaning. Heavy metals are often found in the silt fraction, while organic micro pollutants occur in the silt fraction and sometimes also as tar particles in the sand fraction. The sediment can be cleaned by physical means or by the selective separation of some of the contaminants by froth flotation. Research into the efficiency of using separation on the basis of particle size to clean contaminated sediments from five different sites and also the experience gained during three sediment clean-up operations, indicated that positive effects could only be achieved in sandy sediments. In some cases, owing to the presence of tar particles in the sediment, the quality of the sand fraction was not improved after separation in hydrocyclones. They can be removed from the sand fraction by flotation. Recent developments in selective separation by means of froth flotation, using equipment specially designed for the fine fraction, are promising. The use of duo-flocculants has a favourable influence on the consolidation behaviour of the fine fraction after separation.

Monitoring of environmental effects and process performance during biological treatment of sediment from the petroleum Harbour in Amsterdam

1998 ◽  
Vol 37 (6-7) ◽  
pp. 395-402
Author(s):  
Guus C. Stefess
Keyword(s):  
Environmental Effects ◽  
Organic Contaminants ◽  
Biological Treatment ◽  
Biological Process ◽  
Froth Flotation ◽  
Fine Fraction ◽  
Dry Weight ◽  
Pilot Project ◽  
Mineral Oil ◽  
Silt Fraction

A full-scale (470 m3) process for biological treatment of dredging spoil from the Petroleum Harbour in Amsterdam has been monitored during a pilot project. The dredging spoil was heavily polluted with polycyclic aromatic hydrocarbons (PAH) and mineral oil. The remediation chain involved dredging, transport of dredged spoil, hydrocyclone separation, froth flotation of the coarse particles, and biological treatment of the silt fraction (<20 μm) in stirred bioractors. The independent monitoring was aimed at recording the environmental effects, product quality and performance of the biological process. Hydrocyclone separation (cut point 20 m) resulted in two bulk streams: 65% sand and 30% silt (based on total dry weight of the input). The sand was cleaned and could be reused as building material. PAH and mineral oil were successfully concentrated in the silt fraction (<20 μm), which was treated biologically. Biological treatment during continuous feeding of fine fraction, at a residence time of 8-10 days for the entire bioreactor system, resulted in considerably reduced mineral oil and PAH contents. Furthermore, the leaching of organic contaminants was reduced, as well as the ecotoxicity. The obtained silt product however did not meet the demands, and had to be landfilled. Minor emissions of contaminants were measured in wastewater and offgas. The energy and chemicals consumption were acceptable. The biological process appears to be promising for the treatment of less-severely contaminated dredged material.

Effect of NaCN:ZnSO4 Mixture Molar Ratio and Particle-Size Distribution on Pb-Zn and Fe Selective Separation by Froth Flotation

JOM ◽  
2021 ◽  
Author(s):  
Ramón Arellano-Piña ◽  
Elvia Angélica Sanchez-Ramirez ◽  
Roberto Pérez-Garibay ◽  
Mario Corona-Arroyo
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Froth Flotation ◽  
Selective Separation ◽  
Molar Ratio

scholarly journals The Study of Carbon Recovery from Electrolysis Aluminum Carbon Dust by Froth Flotation

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 145
Author(s):  
Hesong Li ◽  
Jiaoru Wang ◽  
Wenyuan Hou ◽  
Mao Li ◽  
Benjun Cheng ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Mixing Time ◽  
Froth Flotation ◽  
Aluminum Electrolysis ◽  
Carbon Powder ◽  
Molten Salt Electrolysis ◽  
Carbon Recovery ◽  
Aluminum Smelting

A large amount of carbon dust is generated in the process of aluminum smelting by molten salt electrolysis. The carbon dust is solid hazardous waste but contains a large quantity of recyclable components such as carbon and fluoride. How to recycle carbon dust more effectively is a challenge in the aluminum electrolysis field. In this study, X-ray diffraction, scanning electron microscope, and other methods were used to analyze the phase composition of electrolytic aluminum carbon dust. The effects of particle size distribution of carbon dust, impeller speed, reagent addition, mixing time, and flotation time on the flotation recovery of carbon dust were studied. The optimal flotation conditions were obtained and the flotation products were analyzed. The results show that the optimal particle size distribution is 70% of particles below 200 mesh, corresponding to a grinding time of 11 min. The optimum speed of the flotation machine was to be between 1600 and 1800 r/min with the best slurry concentration of 20–30% and 5 min mixing time, and the collector kerosene was suitable for adding in batches. Under the above conditions, the recovered carbon powder with a carbon content of 75.6% was obtained, and the carbon recovery rate was 86.9%.

scholarly journals Effect of Flotation Time and Collector Dosage on Estonian Phosphorite Beneficiation

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 114
Author(s):  
Kadriann Tamm ◽  
Zeinab Arab Zadeh ◽  
Rein Kuusik ◽  
Juha Kallas ◽  
Jason Yang ◽  
...  
Keyword(s):  
Phosphate Rock ◽  
Froth Flotation ◽  
Fine Fraction ◽  
The European Union ◽  
High Recovery ◽  
Know How ◽  
Cellular Processes ◽  
Reliable Source ◽  
Living Organisms ◽  
The Relationship

Phosphorus is an essential and non-substitutable element for the cellular processes of all living organisms. The main source of phosphorus in the biosphere is phosphate rock. With more than 700 Mt phosphate rock, Estonia holds the largest sedimentary phosphate rock deposits in the European Union. Estonian phosphate rock is particularly outstanding due to its remarkably low content of hazardous heavy metals such as Cadmium (<5 ppm) and trace elements of Uranium (<50 ppm). It is also a reliable source of valuable elements such as rear earth elements (REEs). The aim of this study was to investigate the distribution of the main minerals (apatite and quartz) between slimes, tailings, and concentrates that formed at the froth flotation of Estonian phosphate rock with the up-to-date level of know-how and techniques. Subsequently, the relationship between the obtained grades and recovery levels in concentrates was determined based on the collector dosage and flotation duration. It was observed that the fine fraction of the tailings contains 17.9–33.49 wt% P2O5 that can be added to the final product. Moreover, it was found that, with the lower dosage of the collector, the extended flotation time does not influence the phosphate grade and a high amount of quartz remains in the concentrates. It was also shown that, by raising the collector dosage and setting the flotation time, an adequate grade (>32 wt% P2O5) and recovery (up to 98%) can be gained. The results showed that Estonian phosphate rock can be beneficiated to produce a high-quality concentrate at high recovery levels by modifying the main flotation parameters depending on the properties of the ore.

The Use of Froth Flotation for Selective Separation of Plastic Wastes from Soil

2021 ◽  
Vol 6 (4) ◽  
pp. 135-138
Author(s):  
Kofi Moro ◽  
Dorothy A. Dechie
Keyword(s):  
Surface Properties ◽  
Polyethylene Terephthalate ◽  
Tannic Acid ◽  
Froth Flotation ◽  
Selective Separation ◽  
Composite Sample ◽  
Molecular Weights ◽  
Plastic Wastes ◽  
Chain Lengths ◽  
Selective Separations

  The Use of Froth Flotation for Selective Separation of Plastic Wastes from Soil   Kofi Moro and Dorothy A. Dechie   Abstract — In recycling of plastics, unless the goal is to form composites or materials having special properties, it is not advisable to mix plastics of different kinds because of the differences in their molecular weights and chain lengths. Hence, there is the need to separate these plastics when they are mixed before recycle can be done. This project investigated the selective separation of Polypropylene (PP), Polystyrene (PS) and Polyethylene terephthalate (PET) plastics out of soils using froth flotation. Pulverized samples were prepared from post-consumer plastic sources (PP, PS and PET) and soil and mixed uniformly to form a composite sample. The composite sample was subjected to froth flotation. Two tests were performed. A first test, where there was no addition of a depressant (tannic acid), and a second test, where there was addition of tannic acid to depress some of the plastics in order to selectively separate them. Recoveries from each test work indicated that, plastics are naturally hydrophobic and can be floated out of soils without modifying their surface properties. However, selective separations of the plastics were achieved when tannic acid was used to modify the surface properties of the plastic types.

scholarly journals Leaching Chalcopyrite with High MnO2 and Chloride Concentrations

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 107 ◽  
Author(s):  
David Torres ◽  
Luís Ayala ◽  
Ricardo I. Jeldres ◽  
Eduardo Cerecedo-Sáenz ◽  
Eleazar Salinas-Rodríguez ◽  
...  
Keyword(s):  
Particle Size ◽  
Industrial Waste ◽  
Fine Particles ◽  
Froth Flotation ◽  
Chloride Content ◽  
Tailings Dams ◽  
Processing Strategies ◽  
New Processing ◽  
High Chloride ◽  
Chloride Concentrations

Most copper minerals are found as sulfides, with chalcopyrite being the most abundant. However; this ore is refractory to conventional hydrometallurgical methods, so it has been historically exploited through froth flotation, followed by smelting operations. This implies that the processing involves polluting activities, either by the formation of tailings dams and the emission of large amounts of SO2 into the atmosphere. Given the increasing environmental restrictions, it is necessary to consider new processing strategies, which are compatible with the environment, and, if feasible, combine the reuse of industrial waste. In the present research, the dissolution of pure chalcopyrite was studied considering the use of MnO2 and wastewater with a high chloride content. Fine particles (−20 µm) generated an increase in extraction of copper from the mineral. Besides, it was discovered that working at high temperatures (80 °C); the large concentrations of MnO2 become irrelevant. The biggest copper extractions of this work (71%) were achieved when operating at 80 °C; particle size of −47 + 38 µm, MnO2/CuFeS2 ratio of 5/1, and 1 mol/L of H2SO4.

scholarly journals Spatial variability of particle size fractions of an Oxisol cultivated with conilon coffee

Revista CERES ◽  
2012 ◽  
Vol 59 (6) ◽  
pp. 867-872 ◽  
Author(s):  
Julião Soares de Souza Lima ◽  
Rone Batista de Oliveira ◽  
Samuel de Assis Silva
Keyword(s):  
Particle Size ◽  
Spatial Variability ◽  
Clay Fraction ◽  
Soil Samples ◽  
Landscape Configuration ◽  
Sand Fraction ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Average Value ◽  
Significant Difference

Information on the spatial distribution of particle size fractions is essential for use planning and management of soils. The aim of this work to was to study the spatial variability of particle size fractions of a Typic Hapludox cultivated with conilon coffee. The soil samples were collected at depths of 0-0.20 and 0.20-0.40 m in the coffee canopy projection, totaling 109 georeferentiated points. At the depth of 0.2-0.4 m the clay fraction showed average value significantly higher, while the sand fraction showed was higher in the depth of 0-0.20 m. The silt showed no significant difference between the two depths. The particle size fractions showed medium and high spatial variability. The levels of total sand and clay have positive and negative correlation, respectively, with the altitude of the sampling points, indicating the influence of landscape configuration.

Taguchi Approach and ANOVA in Optimization of the Dissolution of Colemanite in CO2 and SO2- Water Systems

2020 ◽  
Vol 10 (2) ◽  
pp. 88-97
Author(s):  
Zafer Ekinci ◽  
Esref Kurdal ◽  
Meltem Kizilca Coruh
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Gas Flow ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Process Conditions ◽  
Liquid Ratio ◽  
Positive Effects ◽  
Controllable Factors

Background: Turkey is approximately 72% of the world’s boron sources. Colemanite, tincal, ulexite and pandermite are among the most significant in Turkey. Boron compounds and minerals are widely used in many industrial fields. Objective: The main purpose of this study was to investigate the control of impurities in the boric acid production process using colemanite by carrying out the reaction with a mixture of CO2 and SO2 - water, and determining the appropriate process conditions to develop a new process as an alternative to the use of sulfuric acid. Due to worrying environmental problems, intensive studies are being carried out globally to reduce the amount of CO2 and SO2 gases released to the atmosphere. Methods: The Taguchi method is an experimental design method that minimizes the product and process variability by selecting the most appropriate combination of the levels of controllable factors compared to uncontrollable factors. Results: It was evaluated the effects of parameters such as reaction temperature, solid-to liquid ratio, SO2/CO2 gas flow rate, particle size, stirring speed and reaction time. The optimum conditions determined to be reaction temperature of 45°C; a solid–liquid ratio of 0.083 g.mL−1; an SO2/CO2 ratio of 2/2 mL.s−1; a particle size of -0.354+0 .210 mm; a mixing speed of 750 rpm and a reaction time of 20 min. Conclusion: Under optimum operating conditions, 96.8% of colemanite was dissolved. It is thought that the industrial application of this study will have positive effects on the greenhouse effect by contributing to the reduction of CO2 and SO2 emissions that cause global warming.

scholarly journals Variations in selected soil physical properties with landforms and slope within an inland valley ecosystem in Ashanti region of Ghana

2011 ◽  
Vol 6 (No. 2) ◽  
pp. 73-82 ◽  
Author(s):  
S.E. Obalum ◽  
J.C. Nwite ◽  
J. Oppong ◽  
C.A. Igwe ◽  
T. Wakatsuki
Keyword(s):  
Particle Size ◽  
Moisture Content ◽  
Particle Size Distribution ◽  
Physical Properties ◽  
Bulk Density ◽  
Site Selection ◽  
Total Porosity ◽  
Soil Physical Properties ◽  
Silt Fraction ◽  
Inland Valley

One peculiar feature of the inland valleys abundant in West Africa is their site-specific hydrology, underlain mainly by the prevailing landforms and topography. Development and management of these land resources under the increasingly popular sawah (a system of bunded, puddled and levelled rice field with facilities for irrigation and drainage) technology is a promising opportunity for enhancing rice (Oryza sativa L.) production in the region. Information on the variations in selected soil physical properties as influenced by the prevailing landforms may serve as a useful guide in site selection. This is of practical importance since majority of the inland valleys are potentially unsuitable for sawah development and most farmers in the region are of low technical level. Three landforms (river levee, elevated area and depressed area) were identified within a sawah field located in an inland valley at Ahafo Ano South District of Ghana. Each of these landforms was topsoil-sampled along on identified gradient (top, mid and bottom slope positions). Parameters determined included particle size distribution, bulk density, total porosity and field moisture content. The soil is predominantly clayey. There were no variations in the particle size distribution among the slope positions in the river levee. Overall, the river levee had lower silt content than the elevated and the depressed landforms. The bulk density, total porosity, and gravimetric moisture content indicated relative improvements only in the depressed area in the order, bottom &gt; mid &gt; top slope. Irrespective of slope position, the three landforms differed in these parameters in the order, depressed &gt; river levee &gt; elevated. The sand fraction impacted negatively on the silt fraction and bulk density of the soil, both of which controlled the soil moisture status. Despite the fairly low silt content of the soil, the silt fraction strongly influenced the gravimetric moisture content (R<sup>2</sup> = 0.80). So too did the soil bulk density on the gravimetric moisture content (R<sup>2</sup> = 0.90). It is concluded that: (1) since the landforms more prominently influenced the measured parameters than the slope positions, the former should take pre-eminence over the latter in soil suitability judgment; (2) with respect to moisture retention, variations in silt fraction and bulk density of this and other clayey inland-valley soils should be used as guide in site selection for sawah development.

Froth flotation of sphalerite: Collector concentration, gas dispersion and particle size effects

2014 ◽  
Vol 57 ◽  
pp. 72-78 ◽  
Author(s):  
R. Pérez-Garibay ◽  
N. Ramírez-Aguilera ◽  
J. Bouchard ◽  
J. Rubio
Keyword(s):  
Particle Size ◽  
Size Effects ◽  
Froth Flotation ◽  
Gas Dispersion ◽  
Particle Size Effects ◽  
Collector Concentration
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