Abstract: Starches are widely used as depressant in froth flotation operations in Brazil due to their efficiency, increasing the selectivity in the inverse flotation of quartz depressing iron ore. Starches market have been growing and improving in recent years, leading to better products attending the requirements of the mineral industry. The major source of starch used for iron ore is corn starch, which needs to be gelatinized with sodium hydroxide (NaOH) prior to use. This stage has a direct impact on industrials costs, once the lowest consumption of NaOH in gelatinization provides better control of the pH in the froth flotation and reduces the amount of electrolytes present in the pulp. In order to evaluate the gelatinization degree of different starches and flour were subjected to the addiction of NaOH and temperature variation experiments. Samples of starch (corn, cassava, HIPIX 100, HIPIX 101 and HIPIX 102 commercialized by Ingredion) and flour (cassava and potato) were tested. The starch samples were characterized through Scanning Electronic Microscopy and the amylose content were determined through spectrometry, swelling and solubility tests. The gelatinization was carried out through titration with NaOH, keeping the solution temperature constant at 40 oC. At the end of the tests, the optimal amount of NaOH consumed to gelatinize the starch or flour from different botanical sources was established and a correlation between the content of amylopectin in the starch and the starch/NaOH ratio needed for its gelatinization.
Abstract: In Brazil, most soils are acidic and low in essential nutrients required for the growth and development of plants, making fertilizers essential for agriculture. As the biggest producer of soy in the world and a major producer of coffee, sugar cane and citrus fruits, Brazil is a large consumer of phosphate. Brazilian’s phosphate ores are predominantly from igneous rocks showing a complex mineralogy, associated with carbonites and oxides, typically iron, silicon and barium. The adopted industrial concentration circuit for this type of ore is a mix between magnetic separation (both low and high field) to remove the magnetic fraction and a froth flotation circuit composed by a reverse flotation of apatite (barite’s flotation) followed by direct flotation circuit (rougher, cleaner and scavenger circuit). Since the 70’s fatty acids obtained from vegetable oils are widely used as lower-cost collectors in apatite froth flotation. This is a very effective approach to the apatite family of minerals, being that this type of collector is both selective and efficient (high recovery). This paper presents Jatropha curcas L. oil (JCO) as a renewable and sustainable source of fatty acids with high selectivity in froth flotation of apatite. JCO is considerably rich in fatty acids such as linoleic, oleic and palmitic acid. The experimental campaign involved 216 tests using a modified Hallimond tube and two different minerals (apatite and quartz). In order to be used as a collector, the oil was saponified. The results found were compared with the synthetic collector, Fotigam 5806 produced by Clariant, which is composed mainly by soy oil. JCO showed the highest selectivity for apatite flotation with cold saponification at pH 8 and concentration of 2.5 mg/L. In this case, the mineral recovery was around 95%.
Abstract: This study evaluated to facilitate separation of ABS
plastics from other waste plastics by froth flotation after surface
hydrophilization of ABS with heat treatment. The mild heat treatment
at 100oC for 60s could selectively increase the hydrophilicity of the
ABS plastics surface (i.e., ABS contact angle decreased from 79o to
65.8o) among other plastics mixture. The SEM and XPS results of
plastic samples sufficiently supported the increase in hydrophilic
functional groups and decrease contact angle on ABS surface, after
heat treatment. As a result of the froth flotation (at mixing speed 150
rpm and airflow rate 0.3 L/min) after heat treatment, about 85% of
ABS was selectively separated from other heavy plastics with 100%
of purity. The effect of optimum treatment condition and detailed
mechanism onto separation efficiency in the froth floatation was also
investigated. This research is successful in giving a simple, effective,
and inexpensive method for ABS separation from waste plastics.
Abstract: In the present study, feasibility of the selective surface
hydrophilization of polyvinyl chloride (PVC) by microwave treatment
was evaluated to facilitate the separation from automotive shredder
residue (ASR), by the froth flotation. The combination of 60 sec
microwave treatment with PAC, a sharp and significant decrease about
16.5° contact angle of PVC was observed in ASR plastic compared
with other plastics. The microwave treatment with the addition of PAC
resulted in a synergetic effect for the froth flotation, which may be a
result of the 90% selective separation of PVC from ASR plastics, with
82% purity. While, simple mixing with a nanometallic Ca/CaO/PO4
dispersion mixture immobilized 95-100% of heavy metals in ASR
soil/residues. The quantity of heavy metals leached from thermal
residues after treatment by nanometallic Ca/CaO/PO4 was lower than
the Korean standard regulatory limit for hazardous waste landfills.
Microwave treatment can be a simple and effective method for PVC
separation from ASR plastics.
Abstract: Froth flotation remains to date as one of the most used
metallurgical processes for concentrating metal-bearing minerals in
ores. Oxide ores are relatively less amenable to froth flotation and
require a judicious choice of reagents for the recovery of metals to be
optimised. Laboratory batch flotation tests were conducted to
determine the effect of two types of gasoil-rinkalore mixtures on the
flotation response of a copper cobalt oxide ore sample. The head
assay conducted on the initial ore sample showed that it contained
about 2.90% of Cu, 0.12% of Co.
Upon the flotation test work, the results obtained indicated that the
concentrate obtained with use of the mixture gazoil-rinkalore RX
yielded 8.24% Cu and 0.22% Co concentrate grades with recoveries
of 76.0% Cu and 78.0% Co respectively. But, the concentrate
obtained by use of the mixture gazoil-rinkalore RX3 yielded
relatively bad results with 5.92% Cu and 0.18% Cu concentrate
grades with recoveries of 70.3% Cu and 65.3% Co respectively.
Abstract: An attempt has been made to beneficiate the Indian
coking coal fines by a combination of Spiral, flotation and Oleo
Flotation processes. Beneficiation studies were also carried out on -
0.5mm coal fines using flotation and oleo flotation by splitting at size
0.063mm.Size fraction of 0.5mm-0.063mm and -0.063mm size were
treated in flotation and Oleo flotation respectively. The washability
studies on the fraction 3-0.5 mm indicated that good separation may
be achieved when it is fed in a spiral. Combined product of Spiral,
Flotation and Oleo Flotation has given a significant yield at
acceptable ash%. Studies were also conducted to see the dewatering
of combined product by batch type centrifuge. It may further be
suggested that combination of different processes may be used to
treat the -3 mm fraction in an integrated manner to achieve the yield
at the desired ash level. The treatment of the 3/1 mm -0.5 mm size
fraction by spiral,-0.5-0.63 mm by conventional froth flotation and -
0.063 fractions by oleo flotation may provide a complete solution of
beneficiation and dewatering of coal fines, and can effectively
address the environmental problems caused by coal fines.
Abstract: This study was carried out to develop a flotation
procedure for an oxide copper ore from a Region in Central Africa
for producing an 18% copper concentrate for downstream processing
at maximum recovery from a 4% copper feed grade. The copper
recoveries achieved from the test work were less than 50% despite
changes in reagent conditions (multistage sulphidisation, use of RCA
emulsion and mixture, use of AM 2, etc). The poor recoveries were
attributed to the mineralogy of the ore from which copper silicates
accounted for approximately 70% (mass) of the copper minerals in
the ore. These can be complex and difficult to float using
conventional flotation methods. Best results were obtained using
basic sulphidisation procedures, a high flotation temperature and
extended flotation residence time.
Abstract: The aim of this study is to compare the effect of the ultrasonic pre treatment on the removal of heavy metals (Iron, Zinc and Copper) from Acid Mine Drainage (AMD) by Denver Cell flotation. Synthetic AMD and individual metal solutions are used in the initial experiments to optimise the process conditions for real AMD. Three different process methods, ultrasound treatment followed by Denver flotation cell, Denver flotation cell alone and ultrasonic treatments run simultaneously with the Denver flotation cell were tested for every sample. Precipitation of the metal solutions by using sodium hydroxide (NaOH) and application of the optimum frother dosage followed by flotation significantly reduced the metal content of the AMD.