United States Florida Phosphate Re-election Of Wastewater Flocculation Dewatering And Sediment Transport Rheological Properties

At present phosphatic waste clay produced from phosphate weight -beneficiation has typical colloidal character and it is very difficult to separate solids from suspension in the world.Most of phosphatic waste clay was stored in huge clay ponds,tailing dams or useless mines of underground,which leads large areas of land to be occupied and a lot of water resource to be wasted,this store phosphatic waste clay approach also brings potential danger of dam failure and seepage.So how to find an economical and practical technology for processing phosphatic waste clay is a crucial problem in the world.The phosphate weight -beneficiation waste clay cann't be solved in Florida of USA,so there was a great pressure on entironment and water resources used.This paper discussed the technology that how to treat phosphate weight-beneficiation waste clay and reuse water in Florida.Through analyzing treatment technology of mine wastewater and phosphate beneficiation wastewater in the world,according to correlative theories and research methods to study experimental treatment technology for processing phosphatic waste clay.Base on the best integration experimental conditions,and pilot scale tests were done which results was accorded with experimental tests.Then design the technology of industrial test use for processing phosphatic waste clay.This research is not only significant for solving the pollution of phosphate waste clay,reusing water and land resource for phosphate company in Florida,but also is a important for consulting on processing phosphatic waste clay in China.1.This paper uses American Ciba UMA organic macromolecule flocculants came from Ciba chemical company to treat phosphate waste clays.High effective flocculation can be performed to phosphatic waste clay produced from phosphate weight-beneficiation.The relationships between flocculation effects and flocculant's concentration,dosages and pH values is mastered.2.By adding flocculants time after time and adding sand to help flocculate,the relationship between flocculating effects with adding sand dosage and flocculant times had been found when flocculant's concentration,dosage and mixing style is constant.All these will be used to choose the best flocculation technology.3.According to colloid particles' composition and surface characters,it is found that particle' base faces are different from edge faces in surface character,particle's active position.is on its edge faces.4.When we combined K⁺ ion,Ca²⁺ion and Al³⁺ion with organic macromolecule flocculants together to research,it is found that the place flocculant's long trains was adsorbed on was located on particles' edge faces.The promotion effect of K⁺ ion on flocculation is much better than the action of Ca²⁺ion and Al³⁺ion,Ca²⁺ion and Al³⁺ ion even has an averse effect on flocculation in a certain range of concentrations and pH values,this phenomena deviates from traditional Schulze-Hard aggregating settling- rule.This paper analyzed this phenomena according to colloid-surface chemistry and solution chemistry.5.Through dynamics researches on adding flocculants time after time and adding sand,it is found that crystal-core particles' amounts is increased in flocculation reaction after sand is added,by action of inertia centrifugal power and yield stress, the unstabilized particles grow up quickly.Adding flocculants time after time can increase effective impact times between particles,making flocculation's half life to be shorten.6.Our research did some tests about pulse- electric flocculation,but it is found there was a bad flocculent action in various different conditions of electrode stations and pulse-electric current.When we combine pulse-electric flocculation with physical-chemistry flocculation together,no good result was get,it was found that the electric field has a restraining effect on flocculating of organic macromolecule flocculant DPW-1-1355.7.According to all the flocculation tests,it was found that the best technics of pilot-scale testing is KCl,5%sands arid 18×10^-6gram flocculant DPW-1-1355 is added into 482ml suspension in turn and KCl's concentration is 10^-3M,flocculant DPW-1-1355 is averagely added five times.In this condition the flocculent settling rate is fast,supernatant turbidity is low,underflow solid concentration is high,and run cost is low.8.According to various tests,the underflow rheology law under the best technics condition is get:(1)The underflow's apparent viscosity is increased with shear rate increasing.When clay concentration is 15%and 20%,both relationship is accord with power relation(η_α=kD^n-1and n＞1,so underflow is characterized by an increasing viscosity with an increase in shear rate that is namely dilatant.It means that the underflow is more denser with stirring going on.(2)The underflow's yield stress is increased with clay solid concentration increasing.It was found that relationship between both them can be expressed by a unitary quadratic equation:Ï„=5.436C²-80.489C+215.67,correlative coefficient R² is 0.9639.(3)It is found that the yield stress of underflow that its clay solid concentration is 20%is slowly decreased with increasing temperature.The relationship between both them can be expressed by a linear equation:Ï„=-0.7264T+829,correlative coefficient R² is 0.9528.(4)By the research of relationship between theology and time,when clay solid concentration is 20%and under condition of a constant shear rate,the viscosity of underflow is depressed with increasing rotating time is found.So it can be judged that underflow is thixotropic..(5)By the research of pH's effect on rheology,it is found that when pH value is 8, and unerflow clay solid concentration is 20%,the yield stress of unerflow will reaches the lowest.(6)By the research of modifying under-paste' s rheology,it was found that modifier DP-203 had an effect on reducing under-paste ' s yield stress.9.Ciba flocculant and K⁺ ion was complexed together to be used.Half-industrialized test was performed that "deep cone thickener" was the primary equipment,added flocculants time after time and added tailing sand to help flocculation.It was found that outlet water's quality was fit for being reused and under-paste's solid concentration is fit for filling underground mine well.This research not only solved purifying problems of phosphatic waste clay produced from phosphate weight -beneficiation and under-paste's concentrating problems,but also came true resource uses of wastewater and under-paste.10.Through industrialized simulative design,it is found if research results is performed in industry,the project's investment and run cost will be cost-effective,it is also proved that there will be a wide application foreground for research results.