Treatment filter cakes

The KDF Filter. The KDP filter (Pig. 23) (Amafilter, Holland) is based on the same principle as disk filters. It was developed for the treatment of mineral raw materials, like coal flotation concentrates or cement slurries, and can produce a filter cake of low moisture content at very high capacities, up... 

Rotary Kiln Incinerators. The rotary kiln has been used to incinerate a large variety of Hquid and soHd industrial wastes. Any Hquid capable of being atomized by steam or air can be incinerated, as well as heavy tars, sludges, pallets, and filter cakes. This abiUty to accept diverse feeds is the outstanding feature of the rotary kiln and, therefore, this type of incinerator is often selected by the chemical and waste treatment industries. 

CeUulosic fibers, powdered limestone, gHsonite, and asphalt are frequently added to both water and oH muds at levels of 10 to 25 kg/m (4—10 lb /bbl) when high differential pressures are encountered to control seepage losses to the formation. This treatment also is used to improve the quaHty of the mud filter cake to reduce the chance of differential pressure sticking. 

Elemental phosphoms from the electrothermal process is a distilled product of high purity and yields phosphoric acid pure enough for most industrial uses without any further treatment. The main impurity is ca 20—100 ppm arsenic present in the phosphoms as the element and in the phosphoric acid as arsenious acid. To remove the arsenic, the phosphoric acid destined for food, pharmaceutical, and some industrial-grade appHcations is treated with excess hydrogen sulfide, filtered, and blown with air to strip out excess H2S. This treatment generally reduces the arsenic content of the phosphoric acid to less than 0.5 ppm. The small amount of filter cake is disposed of in approved chemical landfills. 

Use of Surfa.cta.nts, Although the use of steam to improve dewatering is consistently beneficial, the effects of surfactants on residual moisture are highly inconsistent. Additions of anionic, nonionic, or sometimes cationic surfactants of a few hundredths weight percent of the slurry, 0.02—0.5 kg/1 of soHds (50), are as effective as viscosity reduction in removing water from a number of filter cakes, including froth-floated coal, metal sulfide concentrates, and fine iron ores (Table 2). A few studies have used both steam and a surfactant on coal and iron ore and found that the effects are additive, giving twice the moisture reduction of either treatment alone (44—46,49). 

Filtration. Diatomite is used as a filter aid for appHcations with difficult-to-filter soflds to improve permeabiUty of the filter cake, to prevent the blinding of filter elements, and where high clarity is required such as in the poHsh filtration of wine (qv) or beer (qv) before bottling. It is also used in sugar (qv) refining, water treatment, and in the production of fmit juices (qv) and industrial chemicals. 

Coal Slurries - Two component treatments prove to be effective on a commercial scale for coal slurry flocculation. The use of encapsulated floccuiant suspended in a counter charged floccuiant provides the robusmess of traditional dual component systems, but with additional performance advantages, which include reduction in filter cake moisture content and an increased throughput rate. Figure 5 illustrates the typical filter cake moisture content obtained by a conventional treatment system compared to the encapsulated treatment system using coal tailings as the substrate. 

Solid Solid Solid-liquid Sludge, wet solid Asbestos insulation heat treatment salts, pulverized fuel ash refuse Filter cake Sewage sludge... 

The filter-cake formed in this process, however, is highly dispersible to the produced fluid and thus is effectively removed by placing the well on production. No acid treatment or other removal techniques are required. The primary bridging agent in this fluid is a sized calcium carbonate with particle sizes capable of initiating bridging in pore diameters in excess of 100 p. 

To remove filter-cake, a physical method can be applied wherein a fluid is oscillated in the annulus prior to cementing [948,949]. The direction of flow of the fluid in the annulus is changed at least twice. The oscillatory flow of the fluid removes the drilling mud and the filter-cake from the annulus. After this oscillatory flow treatment, the cement slurry is pumped into the annulus. 

The quality of the KMn04 and CUSO4-5H2O varies with the supplier and affects the yield. Consequently, some hydroxy add, instead of the lactone, may be formed. In such a case, treatment with sodium metabisulfite solution followed by addification, converts any free acid retained on the filter cake into ladone. 

Equation 7 is based on a number of assumptions and may not apply in all cases, especially if the filter cake is compressible. A rigorous treatment of cake filtration has been given by Willis and Tosun (7). 

Rhenipal A sewage sludge treatment process. One of three proprietary additives is used be-fore dewatering. The resulting filter cake is smaller in volume, has less odor, and its heavy metals are insoluble. Offered by Rhenipal, UK, a joint venture between National Power and Dirk European. 

In Step 7, after the energetics hydrolysate from the continuously stirred tank hydrolysis operation has been pumped into a holding tank, acid is added to precipitate aluminum, and the hydrolysate is filtered through an automatic filter press to remove precipitated aluminum compounds. The liquid effluent goes to the dunnage hydropulper (Step 9). The filter cake from the press is sent to an electrically heated screw conveyor (Step 15) for 5X treatment. 

Disposal of solid wastes is a significant problem for the petrochemical industry. Waste solids include water treatment sludge, ashes, fly ash and incinerator residue, plastics, ferrous and nonferrous metals, catalysts, organic chemicals, inorganic chemicals, filter cakes, and viscous solids. 

In order to remove the suspended solids, the purge treatment system contains a clarifier to separate the suspended solids and a filter press or dewatering bins to concentrate the solids into a filter cake, which is cohesive and can be readily disposed. The scrubber purge enters the clarifier from a deaeration tank. The solids settle out in the clarifier and are removed from the clarifier in the underflow. The underflow from the clarifier is sent to a filter press or dewatering bins where the excess water is removed. The solids are sent to disposal while the water is returned to the clarifier. The effluent is then sent to the oxidation towers. 

Treatment produces lower volumes requiring disposal, and the solids filter cake formed may allow for disposal as nonhazardous waste. 

Thermal desorption is a technology that physically separates volatile and some semivolatile contaminants from contaminated media. In thermal desorption, heated air is used to volatilize contaminants at temperatures below those used for incineration. There are both in situ and ex situ applications of the technology. Ex situ treatments typically are used to remediate soil, sediments, sludges, and filter cakes. In situ applications of the technology use injected steam, thermal blankets, or heat supplied by electrodes to volatilize contaminants, which are then removed using extraction wells. 

The filter cake and the distillate must be treated with nitric acid to decompose the contaminates of iron carbonyl complexes. This treatment should be done very carefully in a well-ventilated hood, because carbon monoxide is evolved vigorously. 

A conventional wastewater treatment system with an average flow rate of 160,000 gpd produces effluent suitable for NPDES discharge. Metal hydroxide sludges are dewatered in a 15 cu. ft filter press producing more than one half ton of filter cake per day. The filter cake is further dewatered in a 7 cu. ft, batch-type sludge dryer. Based upon recommendations by their consultant, the firm also uses the sludge dryer to dehydrate nickel strip solutions. Two reverse osmosis systems are used for partial nickel recovery. Trivalent chromium is recovered by drag-out control and evaporation. 

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