Part 1 of 2 for Doug's Wild Goose Chase sponsored by Thor's Wild Guessing
The World's Only Commercial Technology That Utilizes Immobilized Ligands
for Heavy Metal Removal From Water
MGI uses columns filled with Octolig to treat waste streams that
contain regulated heavy metals.
Column diameters are from 12 inches to 42 inches. Each of the largest
columns may handle up to 25 GPM of direct feed. If more water needs to
be treated, any number of columns may be operated in parallel to achieve
the flow requirements.
Precipitation and filtration may be used prior to the Octolig MRP
treatment when high concentrations of heavy metals are present.
Carbon filters or absorbents may be used as a preliminary step for
optimal performance, when organic compound impurities, such as oils and
greases, are present.
Octolig is immobilized by chemically bonding a ligand to a silane that
has been chemically bonded to silica gel. Metal removal and retention is
a result of chelation by the ligand; therefore, Octolig acts as a
host to the heavy metals.
Octolig is extremely insoluble and is stable in aqueous solutions in
the pH range of 0.5 to 10.5 and in the temperature range of 0 C to +80 C.
Extremely high selectivities for heavy metals make Octolig very
efficient at removing metals from water.
Octoligretains ions or metal complexes. Before it is loaded with heavy
metals, Octolig has the appearance of fine white sand. When the system
is loaded with heavy metals, the column changes to the color of the
heavy metals it has retained
Mine Drainage Applications
An ideal metal removal treatment sequence for mine drainage water is a
settling pond followed by treatment with an Octolig MRP (Metal Removal
Plant). Lime is added to the incoming drainage water to increase the pH
to an optimum pH for Octolig treatment. At the increased pH, high
concentrations of heavy metals may produce some heavy metal
precipitation in the settling pond.
After the addition of lime to the mine drainage water, the heavy metal
concentrations remaining in the drainage water usually are greater than
the permitted limits. Passing the settling pond's overflow through the
Octolig MRP consistently reduces the heavy metal concentrations to a
fraction of a part per million.
Octolig MRP system requires little maintenance and has low operating
costs, which make it ideal for an economical metal removal treatment
system for mines.
Leadville Drain
A large scale pilot plant was operated at the drainage tunnel near
Leadville, Colorado. The primary contaminating metals in the drainage
were copper and zinc. During the pilot test, a 100,000 gallon quantity
of contaminated mine drainage water was Octolig MRP treated. The
average influent and effluent concentrations were:
MetalUntreated WaterOctolig Treated WaterCu12.5 ppm.29 ppmZn7.2 ppm.50
ppm
This plant-scale pilot test proves that Octolig treatment reduces heavy
metal concentrations to concentrations of parts per billion.
The Berkeley Pit
A large pilot plant test was conducted at the Berkeley Pit in Montana.
The Berkeley Pit is an open pit that contains highly toxic water,
especially toxic to wildlife. The main poisonous heavy metal is copper,
but numerous other heavy metals are present. The pit water is quite
acidic. Therefore, the pH of the pit water was raised to a pH of 8.3 to
ensure optimum performance of the Octolig MRP. Most of the heavy metals
precipitated and were settled out of solution. In the clear overflow,
some of the heavy metal concentrations were still above the permitted
limits. Octolig MRP treatment removed most of the remaining metals. The
results were:
Untreated InfluentOctolig Treated EffluentpH2.58.3Al341 ppm< 0.3 ppmCd
2.6 ppm< 0.03 ppmCu208 ppm< 0.1 ppmFe908 ppm< 0.1 ppmMn248 ppm < 0.05
ppmNi1.3 ppm< 0.1 ppmZn703 ppm0.1 ppm
The pilot plant test demonstrated that the Octolig MRP treatment
reduced heavy metal concentrations to parts per billion.
Projected Costs of a Full Scale Berkeley Pit Treatment:
For this application, it is estimated that 3 million gallons must be
treated every day to maintain the pit water at a constant level. The
projected figures for Octolig treatment of 3 million gallons per day
are:
MetalsPounds Removed Each DayAl8500 poundsCu5200 poundsFe27,200 poundsMn
6200 poundsZn17,000 pounds
The total precipitate would be 163,000 pounds per day, dry basis.
The cost per year for lime: $ 3,200,000Total operation cost per year:$
4,600,000Octolig MRP Treatment System investment cost:$6,300,000
Summitville
At the Summitville mine near Del Norte, Colorado, an on-site pilot plant
was operated on the drainage water from the cyanide destruction process
(CDP). The CDP was for the destruction of the cyanide in the leach pit
water. In the normal operation of the CDP, hydrogen peroxide was added
to the basic solution, then the precipitated heavy metals were filtered
out. At a pH of 10.3, the CDP effluent was passed through the Octolig
MRP. The concentrations of the heavy metals were:
Untreated InfluentOctoligTreatedAl1200 ppm.18 ppmCd.6 ppm< .001 ppmCu
100 ppm< .013 ppmFe 1250 ppm< .006 ppmMn120 ppm.048 ppmNi4 ppmN/DZn80
ppm< .001 ppm
In conjunction with simple pH adjustment and consequent precipitation,
the Octolig MRP treatment reduced heavy metal concentrations to the
parts per billion range.
A Colorado Gold Mine
An Octolig MRP is currently being installed at a gold mine located in
the mountains west of Denver, Colorado. Although, the mine is a gold
mine, the primary contaminating metal in the mine drainage water is
zinc. The mine discharges 4 million gallons of mine drainage water per
year. Lime is added crudely to the mine drainage water as it flows into
a 33 ft. by 40 ft. by 3 ft. deep settling pond. The overflow from the
settling pond will be pumped continuously through the Octolig MRP.
During the pilot test, the Octolig MRP treated water contained 0.2 to
0.6 ppm of zinc. Operating costs of this installation are less than $
.70 per 1000 gallons of drainage water.
Electroplating Applications
The Octolig MRP System
The Octolig Metal Removal Plant is very simple to operate, and few
controls are needed. The Octolig MRP may be installed next to the
plating line or up to 100 yards away. When the pH of the waste stream is
above 5.5, the Octolig MRP may handle the live rinse water directly
with no added chemicals. Otherwise, a few grams of caustic soda or
sodium carbonate may be added during a shift to raise the pH of the
system.
In an electroplating facility, the most effective, efficient, and
economical way to employ Octolig treatment of live-rinse water is to
use a separate Octolig MRP column on each individual plating line. On
each line, either two drag-out tanks or spray-rinse-plating-items twice
is employed. Many times, a 95-98% portion of the Octolig treated live
rinse water may be returned to the live rinse tank for reuse. See the
following flow chart as an example.
Drag-Out Tanks and Octolig Treatment
When using the Octolig MRP, another ideal operation method for the
plater is to use two drag-out tanks in a series followed by a live-rinse
tank. A volume of water equal to four to six times the original drag-out
volume from the plating tank is returned to the plating tank. Water from
the live-rinse tank is treated by the Octolig MRP and the Octolig
treated water is recycled back to the live-rinse tank. Each day, a small
portion of the live-rinse water is discharged to the sewer and a major
portion is recycled.
Spray-Rinsing and Octolig Treatment
Spray-rinsing is another option if the plating facility is limited on
space.
In an ideal spray-rinsing method, the plater drains the plated items
over the plating tank for fifteen to thirty seconds; then the items are
spray-rinsed twice with deionized water. After each spray rinse, the
plated items are allowed to drain for fifteen to thirty seconds,
followed by a rinse in a live-rinse tank. Water from the live-rinse tank
is treated by the Octolig MRP. After the Octolig treatment, a major
portion of the live-rinse water is recycled to the live-rinse tank and a
very small portion is discharged to the sewer.
Excess Water From Drag-Out and/or Spray-Rinsing
Using the drag-out tank sequence or the spray-rinse method, more water
is returned to the plating tanks than is dragged out. If the plating
tank is kept above room temperature and uncovered, usually the excess
water is evaporated away. If the plating tank is kept below 40 C, the
excess water is evaporated away by pumping a small stream into an open
tank that has an electric immersion heater. Using gravity flow, the
concentrated solution is returned to the plating tank.
Precipitation Pretreatment and Octolig Treatment
When the plated items are taken directly from the plating tank to the
live-rinse tank, the concentration of the heavy metals in the live-rinse
water may be 250 ppm. Generally, an electroplater compensates for that
by using more water and the concentration of the heavy metals is in the
range of 40 ppm. Typically, an electroplater may use 8 GPM of fresh live
rinse water. If 8 GPM of rinse water that contains 40 ppm of heavy
metals were passed through a single 24 inch diameter Octolig column,
the Octolig would have to be regenerated after three eight hour shifts.
Therefore, precipitation pretreatment is recommended prior to the
treatment with the Octolig MRP.
Batch-precipitation treatment is preferred over continuous-flow
precipitation. When using continuous flow, 37% of the initial influent
still remains in the tank after the volume of one tank of fresh water
has flowed into a live-rinse tank. Continuous-flow precipitation occurs
with any system that uses a continuous flow sequence of pH adjustment,
mixing, clarification, and filtration. After batch precipitation, the
filtered filtrate is passed through the Octolig MRP. With this method,
the Octolig MRP may operate for longer periods of time, in some cases,
as long as 120 eight hour shifts.
Electroplater in Nebraska
An Octolig MRP has been installed in a plating shop in Nebraska. The
plating shop has two plating lines; a nickel line and a chromium line.
Currently, the plating shop uses 2800 GPD of recycled Octolig treated
water on the nickel plating line and only 10 GPD of fresh water. The
concentration of the nickel in the plating tank is 100,000 ppm. The
nickel plating line drag-out is 1.75 GPD and 7 GPD of spray-rinse water
and/or dead-tank rinse water is returned to the plating tank. An average
concentration of nickel in the untreated live rinse water going into the
Octolig MRP is 4.1 ppm. Even after several months of operation, the
average concentration of the Octolig treated water is 1.6 ppm. Only a
10 GPD volume of Octolig treated water is discharged to the sewer.
Without the combination of Octolig treatment and the spray-rinse
operation, a drag-out volume of 1.75 GPD with a nickel concentration of
100,000 ppm would lose and waste 662 grams of nickel each day. With the
Octolig treatment, 96% of that nickel is returned to the plating tank.
Each day, a 26.5 gram quantity of nickel is retained in the Octolig
MRP. Only a 10 GPD volume of Octolig treated rinse water is discharged
to the sewer. The 10 gallons contains a maximum of 1.6 ppm of nickel.
The 10 gallon discharge contains 0.061 grams of nickel, an amount that
is about the size of a small fraction of an aspirin tablet.
With Octolig MRP treatment, 99.99% of the total daily nickel is
retained in the plating line or recovered in the Octolig MRP. This
means that less than 1/100 of 1% of the daily nickel is discharged to
the sewer.
A Colorado Plating Shop
The Octolig MRP has been installed in a Colorado plating shop. The
numerous plating lines have copper, nickel, zinc, and chromium present.
Rinse waters from separate plating lines are passed through an existing
precipitation system.
The precipitation process does not reduce the heavy metal concentrations
to below the required limits consistently, so the solution from the
precipitation process is passed through the Octolig MRP to further
reduce the heavy metal concentrations.
Untreated Water Octolig Treated WaterCr0.30 ppmN/DCu0.80 ppm0.21 ppmNi
0.60 ppm0.04 ppmZn4.20 ppm0.07 ppm
The Octolig treated water is recycled and used as wash water. By using
Octolig MRP treatment, this plating shop has reduced its fresh water
usage from 18,000 GPD to 8000 GPD. The 8000 GPD are reused for
pre-plating washes.
Octolig is an immobilized ligand that is chemically bound to a silane
that is chemically bound to silica gel. The ligand chelates heavy metals
as waste water is passed through the column. Octolig acts as a host
to the heavy metals. The heavy metals are retained on the Octolig in a
one-molecule-thick layer on the surface of the silica gel as a result of
chelation. Since all chelation reactions take place on the surface,
contact times between the heavy metals and the Octolig are not
critical.
Octolig is produced from a pH responsive ligand that retains heavy
metals from solutions in a pH range (between pH of 2 to 10) and releases
the heavy metals at high concentrations at a pH lower than 2.
Because of the unique chemistry of the Octolig, the immobilized ligand
complex is very insoluble, and is stable in pH ranges from 0.5 to 10.5
and at temperatures from 0C to over 80C.
Octolig has the capacity to retain ions or metal complexes. Before it
is loaded with heavy metals, Octolig has the appearance of fine white
sand. When the Octolig is loaded with heavy metals, the column changes
to the color of the heavy metals it has retained.
The appearance of the silica gel is deceiving. One kilogram (2.2 pounds)
of silica gel has a dry or wet volume of 2.2 liters (0.6 gallons). The
silica gel has millions of pores, the surface area of which is as much
as 700,000 square meters per kilogram.
When the ligands are bound to the silica gel, the heavy-metal-retention
capacity of the Octolig is as much as 1.0 mole per kilogram. In
industrial applications, the optimum loading capacities are from 0.2 to
0.6 moles per kilogram.
Octolig has enormous stability coefficients that are several
million-to-one to trillions-to-one. This is advantageous when other
common chelators, such as ammonia, are present in the waste stream.
The chelator with the largest stability coefficient has the greatest
affinity for the heavy metals that are present in the solution.
Enormous stability coefficients enable the Octolig to remove heavy
metals from waste streams, even when other common chelators are present
in the solution.
Octolig is selective only for heavy metals. Benign ions, such as
sodium, calcium, sulfate, chloride, etc., are not retained. The
chelation capacity of the Octolig is not reduced by the presence of
these benign ions.
Octolig is a pH-responsive immobilized ligand, not an ion exchange
resin. Because Octolig has large stability constants, Octolig
continues to remove heavy metals from waste streams, even when other
common chelators are present. Octolig has a higher affinity for heavy
metals than ion exchange resins; therefore, Octolig is more selective
for the heavy metals.Because it is selective for the heavy metals,
Octolig consistently removes heavy metals to concentrations of parts
per billion. Octolig has no affinity for benign alkali ions, such as
sodium, calcium, sulfates, chlorides, etc., and those ions are not
retained.All chelation reactions of Octolig take place on the surface
of the silica gel. This enables the Octolig columns to be regenerated
with only a small volume of acidic solution. Contact times are not
critical, unlike with ion exchange resins where contact time is needed
for the reaction to take place. Because chelation takes place on the
surface of the Octoligmolecule, Octolig does not experience fouling.
Octolig may be regenerated hundreds of times without losing its
capacity for heavy metals. Ion exchange resins start to break down after
numerous regenerations, and that lowers their capacity.
Octolig uses a pH-responsive ligand that retains heavy metals from low
concentration solutions in a pH range (between a pH of 2 to 10) and
releases the heavy metal at high concentrations at a lower pH (between a
pH of 0.5 and 1).For regeneration, only a small volume of dilute acid is
needed, followed by washes with water and then by a dilute basic
solution. Usually, the acid regeneration solution will contain a
concentration of heavy metals in the range of 2,000 to 4,000 ppm.The
very small amount of regenerant solution may be precipitated or
evaporated, with the precipitate or the evaporate being sent to a
smelter. Reclaiming is the cheapest way of disposing of heavy metals,
since it ends the disposal liability cost forever.Metre-General, Inc.
wants to help your company. Please fill out the information on the
following data sheet. With the requested information, MGI is able to
design an Octolig system for your specific needs. |
