L.S. Leal Filho

Hydrodynamic dimensionless parameters and their influence on flotation performance of coarse particles

Abstract The upper particle size limit of mineral floatability is a parameter of great importance in the flotation process and the sharp decrease of flotation response when particle size approaches such a limit is a very well known phenomenon. The aim of this research was to find the most suitable hydrodynamic conditions to float coarse particles in microflotation tests. To reach such a target, the influence of some hydrodynamic parameters (Reynolds Number—Re, Froude Number—Fr, Weber Number—We and Power Number—Po) on microflotation response of coarse glass spheres (0.417–0.589mm, 0.208–0.295mm) and quartz particles (0.208–0.295mm) was studied in the presence of the collector ether amine acetate (75 mg/dm 3 ) at pH=10. Maximum flotation response (almost 100%) was observed at 3,000 0.54. For either more quiescent (Re 8,000; Fr>1.0; We>100 and Po

MOLECULAR MODELLING OF REAGENTS FOR FLOTATION PROCESSES

Abstract It has long been recognized that the selectivity of froth flotation processes is highly influenced by the specificity of interactions between minerals and reagents that are used to control the hydrophobic/hydrophilic character of the mineral/water interfaces. We have modelled mineral surfaces (hydroxy-apatite, calcite) and molecules of two polysaccharides (starch, ethyl-cellulose) which are candidates as depressing agents for calcite. A special parameter named “Total Fitting Number” (Ft) was developed to assess the steric compatibility between the structure of both minerals and polysaccharide species. The calculation of Ft was based on measurements of OH-OH distances that exist at reagent molecular structures versus Caue5f8Ca distances that exist along the most common crystallographic orientations (hkl) exhibited by mineral particles. Higher values of Ft were found for the interaction calcite/starch than calcite/ethyl-cellulose. This finding suggests that starch is a more effective depressant for calcite than ethyl-cellulose. However, low values of Ft were found for the interaction apatite/starch and apatite/ethyl-cellulose. This fact means that both substances are unlikely to act as depressants for apatite. Microflotation response of apatite and calcite with sodium oleate (pH = 10.2) in the presence of both polysaccharides corroborates the model.

Plant practice innovations in a phospate concentrator

Abstract Fosfertils Tapira orebody is the most important phosphate deposit in Brazil. A combination of mineralogical and technological features renders the concentration by froth flotation a challenge. The originally designed plant allowed recover of only 40% of the available phosphate rock. The search for a new flotation route started with characterisation studies that revealed the existence of two major kinds of ore: a brittle or friable ore (associated predominantly with siliceous gangue) and a tough or grainy ore (associated predominantly with carbonaceous gangue). Bench scale flotation tests indicated the need for individual circuits for each ore type. The grainy ores required a new reagent scheme, based on the utilisation of a blend of sulphosuccinates, sulphosuccinamates and vegetal origin fatty acids as collector. The friable ores required a special flowsheet with individual circuits for coarse and fine fractions. Such innovations were implemented industrially and allowed the beneficiation of the full orebody.

Process mineralogy studies for optimizing the flotation performance of two refractory phosphate ores

Abstract This paper is a result of research work carried out with three different phosphate ore types (SCO - standard calcitc ore, PCO - phlogopite carbonatic ore, and OCO - olivine carbonatic ore), all of them present on Morro da Mina carbonatic phosphate deposit, exploited by Serrana S.A. de Mineracao, Jacupiranga, Sao Paulo, Brazil. The PCO and OCO types show a refractory behaviour whith respect to flotation. Characterization studies on this three ores were performed, firstly, to understand the reasons for poor flotation performance observed for the two refractory ores. From the characterization programme it was possible to propose and test alternate reagent schemes to treat each of the refractory ores. The major parameters investigated during the characterization programme included surface heterogeneity, collector response and solubility determination. Batch scale flotation tests were performed to investigate the new reagent schemes. These new process routes encompassed the use of different modifier agents for the PCO type and the application of an ancillary non-ionic collector to treat the OCO ore type.

Removal of iron ore slimes from a highly turbid water by DAF

ABSTRACT This paper addresses Dissolved Air Flotation (DAF) process variables, such as the flocculation parameters and the recycle water addition, as well as the pretreatment chemical variables (coagulation conditions), to determine the optimal values for the flotation of iron ore slimes found in a highly turbid water sample from the Gualaxo do Norte River, a tributary of the Doce River Basin in Minas Gerais, Brazil. This work was conducted using a flotatest batch laboratory-scale device to evaluate the effectiveness of DAF for cleaning the water polluted by the Samarco tailings dam leakage and determine the ability of DAF to reduce the water turbidity from 358 NTU to values below 100 NTU, aiming to comply with current legislation. The results showed that the four types of tested coagulants (PAC, ferric chloride, Tanfloc SG and Tanfloc SL) provided adequate conditions for coagulation, flocculation and flotation (in the range of 90–99.6% turbidity reduction). Although the process variables were optimized and low residual turbidity vales were achieved, results revealed that a portion of the flocs settled at the bottom of the flotatest columns, which indicated that the turbidity results represented removal caused by a combination of flotation and sedimentation processes simultaneously. GRAPHICAL ABSTRACT