The Coagulation Process And Regulation Mechanism Of Coal Slime Water Based On The Characteristics Of Floe

In this papera dynamic extraction system for the characteristic parameters of coal slime flocs was established.In view of the difficulty of fuzzy floccs in image processinga method for extracting characteristic parameters of floccs from fuzzy floccs was proposed based on the "clarity" of flocand a quick and accurate software for automatic extraction of characteristic parameters of coal slime flocs was developed.The dynamic variation and mechanism of the characteristics and parameters of the coal slime floes in the process of coagulationflocculation and coagulation were studied;The influence of coagulant flocculant coagulant type and dosage as well as mechanical stirring intensity on the characteristic parameters of floccs was investigated.The function expression of controlling coal slime water settlement effect based on fractal dimension dynamics of flocculation was derived and the feasibility was verified by experiments.A regulation system based on fractal dimension of coal slime floc was put forward before the second part of the coal slime water processing stages which is difficult to settle and provided a feasible solution for the high efficiency settlement and concentration of the coal slieme water.The main conclusions are as follows:（1）The size distribution of coal slime flocs particles follows the power function distribution during the agglomeration process of coal slime water and the corresponding fitting R² values are more than 0.95 the power function distribution parameter β is the particle collision coefficient in the study of agglomeration kineticswhich can be used to express the dynamic cause of agglomeration process.The size distribution of flocs is in accordance with fractal distribution and lognormal distribution during flocculation process of coal slime water.The linear slope corresponding to the fractal distribution is the particle size fractal dimension D_L of coal slime floc particleswhich represents the parameters of complex particle size distribution and the D_L value is smallerthe narrower the particle size distribution of coal slime floc particles.The particle size distribution of flocs particles in the course of coal slime water coagulation and flocculation compaction generally follows fractal distribution and logarithmic normal distributionwhile fitting in the stirring time of 0²0 s when the effect is not goodthere is a small case of fitting R² valuebut with the stirring time prolongingthe fitting effect of floc particle size distribution becomes betterfitting the R² values were above 0.97.（2）The mean particle size of floc particles formed in the course of coal slime water agglomeration is the same with the increase of mixing timethe change rule of all is to rapidly increasethe mixing time of 15³0 s maximumand then slowly decreaseduntil the stable value.The agglomeration process of coal slime water can be divided into four stages: contact stagerapid growth stage of flocculation flocflocculation stage and dynamic equilibrium stage.With the increase of the amount of coagulantthe mean particle size of flocs increasedespecially when the concentration of coagulant increased from 0.1 mmol/L to 0.5 mmol/Lthe particle size of flocs increased significantly at the velocity gradient of104s^-1.With the increase of velocity gradientthe mean particle size of flocs reaches the maximum value when the velocity gradient is 104s^-1and then gradually decreases when the concentration of coagulant NaCl and CaCl₂ is 0.5 mmol/Lit indicates that the velocity gradient of 104s^-1 is the suitable velocity gradient at the concentration of the coagulant.The mean particle size of floc particles was larger than that of NaCl under the condition of adding CaCl₂.（3）The fractal dimension of floc formed in the course of coal slime water agglomeration increases rapidly with the extension of mixing time,after reaching the maximum valuethe fractal dimension of floc decreases gradually.The fractal dimension of the slime floc increases rapidly with the increase of the concentration of coagulantand then decreases slowly at the velocity gradient of 104s^-1.C_NaCl=0.7 mmol/L and C_CaCl2 =0.5 mmol/L are the most suitable coagulant dosage under the velocity gradientwhich makes the fractal dimension value of the slime floc get the maximum value.When the concentration of coagulant is 0.5 mmol/Lthe flocs fractal dimension values are first increases with the increase of velocity gradient and the velocity gradient of 104s^-1when the maximumand then decreasesthat velocity gradient under the 104s^-1 is the concentration of the coagulantthe optimal velocity gradientmake the coal floes fractal dimension reach maximum.The fractal dimension of flocs obtained by adding CaCl₂ is larger than that of flocs corresponding to adding NaCl.The agglomeration process of coal slime water added with CaCl₂ needs more stirring time than that of NaCl adding processso as to promote floc particle structure to achieve the most compact state.Howeverthe corresponding coagulation process requires longer stirring time to promote the agglomeration of flocculated particles to achieve the denser state.（4）The mean particle size of floc particles formed during coal slime water flocculation increases with the increase of mixing time under the condition of high dosage of flocculant or low speed gradientboth increase rapidly and then decrease slowly until they reach a stable state.In other conditionsthe average particle size of floc increases rapidly with the increase of stirring timeand then decreases gradually until it reaches a stable state.The flocculation process of coal slime water can be divided into two types: a)the rapid growth stage and flocculation floc dynamic equilibrium stage stagecontact flocculation floc;b)contact stageflocculation floc fast grow stagefloc flocculation body crushing stage and flocculation floc dynamic equilibrium stage.（5）The fractal dimension value of coal floc decreases with the increase of stirring timethen tends to fluctuate equilibrium stateand increases with the increase of flocculant dosagewhich indicates that the larger floc dosage isthe denser the flocs are formed.The fractal dimension value of the slime floc decreases with the increase of the velocity gradient when the dosage of the flocculant is low 1 mg/L and 2 mg/L.In the high dosage3 mg/L and 4 mg/Lslime floc fractal dimensions numerical respectively in the velocity gradient is 104s^-1 and 139 s^-1 has a minimum valuefloc loose structure corresponding to the velocity gradientthe fractal dimension of floc formed under the condition of velocity gradient of 178 s^-1 is the largestand the corresponding floc structure is dense.（6）The mean particle size of floc particles formed during the coagulation and flocculation of slime water increases rapidly with the extension of mixing timeand then tends to be stable.The process of coal slime water condensation and flocculation can be divided into three stages: contact stageflocculation particle rapid growth stage and flocculation particle dynamic balance stage.The mean particle size of coal slime floc decreases with the increase of coagulant concentration.When the concentration of coagulant NaCl is 0-0.7 mmol/Lthe mean particle size of coal floc particles decreases with the increase of coagulant concentration.When the concentration of coagulant NaCl is greater than 0.7 mmol/Lthe mean particle size of the slime floc decreases slowly until it tends to stability C_NaCl =0.7 mmol/L is the best concentration of coagulant.In the same way C-（CaCl₂） =0.5 mmol/L is the best concentration of coagulant.（7）The fractal dimension of flocs formed in the course of coal slime water coagulation and flocculation blending increases rapidly with the extension of mixing timereaching the maximum valueand then gradually decreases until it becomes stable.When the Coagulant NaCl concentration in 0⁰.7 mmol/L,the coal slime floc fractal dimension increases with the concentration of NaCl coagulant increased rapidlywith the further increase of NaCl concentrationcoal slime floc fractal dimension decreases firstly and then tends to be stablethe C_NaCl =0.7 mmol/Lwhich is the best dosage of the condensation the fractal dimension of flocs reached the maximum.In the same way C-（CaCl₂） =0.5 mmol/L is the best concentration of coagulant to make the fractal dimension of the slime floc reach the maximum（8）The floc densityporositysettling velocity and floc strength can be expressed by the function of fractal dimension.Based on the principle of dimensional harmon yafunctional expression based on fractal dimension of coagulation kinetics is obtained:D_f = K · f₄（GT,Fr）.The feasibility of applying fractal dimension dynamics to control the settlement of coal slime water is verified by experiments.（9）The most suitable energy consumption allocation scheme for the process of slime water flocculation is as follows: G₁T₁=5340,G₂T₂=920;The suitable shear strength of fast stirring and slow stirring during the flocculation process is as follows: F_r1=1.96¹7.26,F_r2 =0.77¹.99;The optimal control range of the two phase fractal dimension in the flocculation process is: rapid agitation stage F_f1=1.952².107 slow stirring stage D_f2=1 896¹.918.The most suitable energy consumption distribution scheme for coal slime water coagulation and flocculation is: G₁T₁=1390,G₂T₂=3560,G₃T₃=1780.The optimum control range of shear strength is suitable for fast stirring and slow stirring during the coagulation and flocculation process:F_r1=3.93⁷.02,F_r2=5.75¹1.51,F_r3 =0.77².88;The optimal control range of the two phase fractal dimension in the coagulation and flocculation process is: agglomerate agitation stage D_f1=1.569¹.717,rapid agitation stage D_f2=1.761¹.886 slow stirring stage D_f3=1.947².105.（10）In a coal treatment plant with difficulty in settling coal slime watera regulation system based on fractal dimension of flocculate body can be establishedand the fractal dimension control of flocculation can be achieved by energy input GT and shear strength Frso that the obtained flocculation particles have a certain density and strength.Thusthe flocculation property is guaranteedand the conditions for subsequent sedimentation concentration and dehydration are created.