CN104445860A - Mud and water separation method for waste drilling sludge of cast-in-situ bored pile - Google Patents

Abstract

The invention discloses a mud and water separation method for waste drilling sludge of a cast-in-situ bored pile. The technical scheme is that a flocculating agent is added to the waste drilling sludge of the cast-in-situ bored pile for flocculating and gel breaking pretreatment. After supernatant liquid is discharged, electrodes are arranged at two ends of the waste drilling sludge, and the two electrodes are charged with low-voltage direct current so as to form a potential difference, and electric dewatering is carried out. The mud and water separation method disclosed by the invention has the characteristics of being good in economy, energy-saving and environment-friendly, safe and convenient to operate, and the like.

Description

A kind of cast-in place pile discarded slurry mud-water separation method

Technical field

The present invention relates to a kind of cast-in place pile discarded slurry mud-water separation new technology, belong to a kind of Novel drilling castinplace pile discarded slurry mud-water separation technology.

Background technology

Along with the continuous enhancing of China's economic strength, each side rapid growths such as China's initial cost and real estate investment.The fast development of investment to construction industry serves keying action.In the foundation basic constructions such as a large amount of deep foundation and basement process, mechanical hole perfusion post is widely applied.But all carry out auxiliary bore hole construction with mud due to general in current mechanical hole perfusion post construction process, thus after pile, building-site must produce discarded slurry pending in a large number.Usually containing various toxic substance in discarded slurry, be discharged in environment and must pollute, therefore must effectively process before discarded slurry discharge.External in the research to process for treating waste sludge resulted technology comparatively early, wherein utilize discarded slurry electroconductibility feature to there has also been some researchs to process mud.In the nineties in 20th century, M.B.Kostic .R.Radakovic .S.Radovanovic and .R.Tomasevic-Canovic have made the experiment changing ground loop resistance with wilkinite and discarded slurry, deposit the effect having in case and can reduce loop resistance for mud there being electrode.

The research of China to the treatment technology of discarded slurry starts from the nineties in last century, has had some be familiar with to discarded slurry harm environment, and the treatment agent starting to find some environmental sounds with carry out discarded slurry architectural study.Some technology obtained from these researchs, mainly contain solidification treatment, dewatering and recovery, burning disposal, backfill process, recirculation use, inject safe formation etc.

In order to decontamination, recycling, Chinese scholars and relevant practitioner have carried out extensive work, also achieve remarkable effect, primary abatement method can be summarized as solidification treatment, injects safe formation, backfill the treatment processs such as process, dewatering and recovery, burning disposal, recirculation use, breakdown of emulsion method, mechanical dehydration method, microbiological treatment, MTC (Mud To Cement) technology now.Wherein breakdown of emulsion method, mechanical dehydration method, microbial method and MTC technology are four kinds of newer processing methodes.Nowadays, domestic development and application reduces the relevant device of water content, mainly contains solid-liquid separation dehydration device and waste disposal plant, as plate and frame(type)filter press, considers belt filter press, horizontal spiral centrifuge.

Which kind for the treatment of technology all has certain scope of application and limitation, the character of discarded slurry that therefore will produce according to each scene on treatment process is selected and the feature such as geography, weather, environment at on-the-spot place carry out the most rational optimized choice, simultaneously in order to the pollution problem of more effective improvement discarded slurry, both source and process control had been need to strengthen, again Development & Multipurpose use new technology.

Summary of the invention

The object of the present invention is to provide a kind of method to enable to process the discarded slurry that cast-in place pile produces fast and efficiently, reduce the processing cost of discarded slurry, make the process of building site discarded slurry more scientific and effective.

In order to this object, the technical solution used in the present invention is as follows:

A kind of cast-in place pile discarded slurry mud-water separation method, is characterized in that: utilize flocculation agent alum to carry out brokenly glue process to discarded slurry; Alum add-on is 0.80% ~ 1.0% of quality of mud fluid; After discharging supernatant liquid, electrodes in mud, forms potential difference; Discarded slurry is dewatered; Finally make handled slime water rate lower than 70%.

When also having Na-CMC or Na in discarded slurry ₂cO ₃, also need the amount adding alum to be n in addition ₃, Na-CMC n ₁and Na ₂cO ₃n ₂the mol ratio of reacting in aqueous with alum is respectively n ₁: n ₃=3:1, n ₂: n ₃=3:2.

Further, described electrode anode material adopts the metallic substance such as iron, aluminium or zinc.

Further described electrode anode material adopts the materials such as copper, carbon or graphite.

Mainly form with discarded slurry and tentatively break glue and be treated to basis, utilize the electric behavior of discarded slurry, fast processing is carried out to the waste mud that cast-in place pile produces.

After discarded slurry adds alum, be swift in response, the fine colloid in system sticks grain coalescent precipitation under the effect of flocculation agent (alum).There is demixing phenomenon in whole discarded slurry system, upper strata is clear liquid, and lower floor is the beds of precipitation.As far as possible thoroughly being separated to realize mud solid-liquid, first supernatant liquid being discharged, then electric dehydration process is carried out to remaining mud sediment layer.

The beds of precipitation water ratio of discharging water is still higher, belongs to the category of mud.Bottom waste drilling mud, arrange electrode, between electrode, pass to low-voltage DC, between electrode, there is potential difference.According to Stern double ionic-layer theory, under DC Electric Field, the electric charge of gegenion can move along the direction of extra electric field, thus liquid also can be driven to move together, and solid layer can move together along with glutinous grain.Finally, arrive the effect of solid-liquid separation, beds of precipitation water ratio significantly reduces.

Compared with prior art, tool has the following advantages and high-lighting effect in the present invention:

(1) economic benefits are good.Use flocculation agent (alum) price cheap, power consumption is few.Whole mud-water separation process comparatively discarded slurry outward transport expense saves 20%.

(2) energy-conserving and environment-protective.Move processed discarded slurry by flocculation electro, avoid the outer problem of environmental pollution abandoned mud and cause.

(3) easy to operate and safe.Adopt low-voltage DC, automatic operation after arrangement of electrodes completes, without the need to artificial operation on duty.

Accompanying drawing explanation

Fig. 1 is the double ionic-layer theory on clay surface;

Fig. 2 is the Stern double ionic-layer theory of colloidal particle;

Fig. 3 is simple electric osmose dewatering system schematic diagram.

Accompanying drawing illustrates: the electrode that 1-base angle is laid; 2-solid-liquid divides aspect; 3-glass electrode groove; 4-power lead; The glass stick of 5-fixed electorde.

Embodiment

Before cast-in place pile uses mud boring, the main component of mud generally comprises wilkinite (main component is montmorillonite), industrial alkali (Na ₂cO ₃, molar mass is 106g/mol), sodium matter carboxymethyl cellulose (Na-CMC, molar mass is 114.115g/mol) and tap water.Note unit volume quality of mud fluid is that mud volume is multiplied by mud balance, is designated as M _z.Wherein the quality of sodium matter carboxymethyl cellulose (Na-CMC) is m ₁, industrial alkali (Na ₂cO ₃) quality be m ₂.M ₁, m ₂equal mud total mass respectively and be multiplied by respective massfraction.Experimentally determine, Na-CMC and Na in discarded slurry ₂cO ₃content is unchanged.

For the discarded slurry that cast-in place pile produces, measure its parameter, comprising: the volume V of discarded slurry, proportion ρ ₀, the sand factor π of discarded slurry and the pH value of discarded slurry.

There is optimum add-on in the add-on of alum.When alum add-on is less, in mud-water separation process, final settlement is not obvious, when alum add-on is excessive, not remarkable to settlement influence, the excessive flocculation agent alum that adds can only the concentration of alum in increase system, breaks glue flocculation inoperative to discarded slurry in system.Experimentally study, breaking glue coagulation process alum optimal addn for pure clay slurrying cast-in place pile discarded slurry mud-water separation is 0.80% ~ 1.0% of quality of mud fluid.Quality of mud fluid is quality of mud fluid after desanding herein, and method of calculation are V ρ ₀(1-π).It is thorough that this add-on makes discarded slurry break glue flocculation sediment, and speed is maximum.In addition, along with adding of alum, the variation tendency of the pH value in system and the proportion variation tendency of supernatant liquid reduce along with the add-on increase of alum.When alum add-on is optimum add-on, pH value in system is 7 ~ 8, and the proportion of system clear liquid is at the middle and upper levels close to the proportion of pure water, and supernatant liquid is clear water substantially, because in cast-in place pile discarded slurry, pollutent is less, supernatant liquid meets the emission standard of country.

For adding Na-CMC and Na ₂cO ₃discarded slurry also should add alum (KAl (SO ₄) ₂12H ₂o, molar mass is 474.3247) with Na-CMC and Na ₂cO ₃reaction.Na-CMC and Na ₂cO ₃the mol ratio of reacting in aqueous with alum is respectively n ₁: n ₃=3:1, n ₂: n ₃=3:2.The extra add-on specifying alum is M _m:

$\begin{array}{c}{M}_m=(\frac{m_1}{114.115}\×\frac{n_3}{n_1}+\frac{m_2}{106}\×\frac{n_3}{n_2})\×474.3247\\ =(\frac{m_1}{342.345}+\frac{m_2}{159})\×474.3247\\ =1.3855m_1+2.9832m_2\end{array}$

What utilize electrical means to have the greatest impact to solid-liquid separation effect and beds of precipitation water content is space D between electrode, potential difference U between electrode, electromotive action time T.Experimental model simulation smaller sized shale pond, adopt the wide * of long * high=20cm*20cm*30cm glass jar.Experimental study shows, interelectrode distance D=11cm, between electrode during potential difference U=10V, and electronic shortest time in electrokinetic process, electronic time T=6h.In rig-site utilization process, because under different condition, certain change can occur mud physico-mechanical properties, this just causes between interelectrode distance D, electrode cannot determine reliably fixed relationship between potential difference U and electronic time T.Therefore will according to on-the-spot mud physico-mechanical properties and execution conditions in actual Specific construction process, before carrying out construction, concrete experiment is determined.Finally with reach to make within the time short as far as possible handled mud reach water ratio lower than 70% state.

Electrode materials is one of principal element affecting electric driving method mud solid-liquid separation effect and energy consumption, the impact of electrode materials be mainly manifested in electric dehydration efficiency, electrode corrosion and work-ing life 3 aspects.Show according to water content of soil after monitoring water displacement, energy consumption, effective electromotive force and solid-liquid separation, corrosion due to metal electrode under higher electromotive force is more serious and affect electric driving method solid-liquid separation effect, so Graphite Electrodes performance is better than other metal electrodes under higher electromotive force.But under lower electrical potential conditions, Graphite Electrodes performance is not as the metal electrode such as iron, copper.Along with the reduction of electromotive force, the difference of iron, graphite, copper and aluminium electrode pair solid-liquid separation effect can reduce gradually.In addition, owing to can there is electrochemical passivation as anode in copper electrode, this will significantly reduce the efficiency of solid-liquid separation, should avoid in engineering as far as possible.In Practical Project, for the electrical potential conditions adopted in concrete mud type and construction, best electrode materials should be selected.When determining, suggestion is conservative adopts iron electrode.

Claims (4)

1. a cast-in place pile discarded slurry mud-water separation method, is characterized in that: utilize flocculation agent alum to carry out brokenly glue process to discarded slurry; Alum add-on is 0.80% ~ 1.0% of quality of mud fluid; After discharging supernatant liquid, electrodes in mud, forms potential difference; Discarded slurry is dewatered; Finally make handled slime water rate lower than 70%.

2. method according to claim 1, is characterized in that: when also having Na-CMC or Na in discarded slurry ₂cO ₃, also need the amount adding alum to be n in addition ₃, Na-CMC n ₁and Na ₂cO ₃n ₂the mol ratio of reacting in aqueous with alum is respectively n ₁: n ₃=3:1, n ₂: n ₃=3:2.

3. method according to claim 1, is characterized in that: described electrode anode material adopts iron, aluminium or zinc.

4. method according to claim 1, is characterized in that: described electrode anode material adopts copper, carbon or graphite.