Options for Reducing Green Sand Wastefrom Foundry Operations

1988 Summer Intern Project

by Lisa Monsour

I 1 1

LJ LZI LZ> LZ L~ Cr1 ç.L~ L2 CJ U C ‘L~~i L-~ LJ E-~P. L2 Ui Ui

The chief intent of this document is to provide information toenable the reader to understand the scope and findings of thisproject; not to provide a polished report. The information inthe report was obtained by the intern student. Major assistancein writing this report was provided by the MnTAP staff.

It should be noted that the accuracy of the data, evaluation ofequipment and conclusions or recommendations are not intended toreflect the judgement of MnTAP, the participating intern company,or equipment vendors. References to specific equipment orchemicals do not represent an endorsement by MnTAP.

NOTE: A company pursuing waste reduction for a similar processis advised to evaluate all the relevant options and equipment fortheir systems.

r r N N

PROJECT SUMMARY

This project focused on reducing the sand waste from a greensand foundry.

In conducting a waste survey at the company, several areaswere identified where waste sand is currently generated.Currently the company ships approximately 1,080 tons of sand off—site yearly. An estimated 45* or 490 tons of that is green sand,the largest single sand wastestream.

Areas identified which are contributing to the green sandwaste included: mixing and testing, molding, shake out, and silostorage The nature of the process made it very difficult toassess losses which could be attributed to any one area.

The following are examples of some of the observations:

— In the mixing area, evaluation of the final mixed sand isprimarily based on a “feel” test of the mixed sand. Asthis is very subjective, some batches of mixed sand arethen rejected when they cannot be used in the moldingprocess.

— In the molding area and shake—out area, if castings areput into the shake—out system too rapidly, the system cannot handle the sand successfully. A large amount ofreusable sand falls into the holding area below theshake—out system.

— In this silo where sand is held for reuse, a percentageof the sand adheres to the walls because of residualmoisture content. This sand then cannot be recirculatedto the molding area.

The suggestions for changes to reduce green sand waste includedoperation and equipment changes in all parts of the process.This is consistent with recommendations of the American FoundrySociety that all areas of the process must be addressed in asatisfactory green sand reclamation system.

Suggested changes included:

— a more comprehensive testing program to minimize sandlosses due to unusable batches of molded sand

— modifying the shake-out area so that the system does notbecome overloaded resulting in sand loss

— modifying the storage area to minimize sand accumulationon the walls of the silo (the storage area).

At the conclusion of the project, no changes had yet beenmade at the company. The report outlines suggestions for changein each of the process areas, and also provides information aboutkinds of equipment that may be useful for specific parts of theprocess.

Table of Contents

Page Number

I II Iatroduct~ry Information .• I

III Project Focus a.ndFoundry Overview 2

IV Process Description - Casting with Green Sand 2

V Waste Survey Information ¶4

VI Options for Reduction of Waste Sand Ii

VII Evaluation of Sand Waste Reduction Potential in Process Operation .. 17

VIII Other Options Reviewed 19

Bibliography 20

Appeiidices

Appendix I Glossary 22

Appendix 2 Sand and Clay Sources . 23

Appendix 3 AFS Function Requirements 24

Appendix 4 Process Equipment and In-House Changes .. 25

Appendix 5 Sand Characterization and Silo Utilization .. 33

1~ I r 1

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¶ I

Lisa M. Monsour. a senIor chemical engineering student at the University ofMinnesota. Expected graduation date is June1989.

11. Company Profile

Employees: There are a total of sixty-four employees, forty-five yorkday shift and seven work night shift during the summer. During the summerNSP gives the company lower rates for off peak electricity usage; consequentlythe number of employees/operating hours vary (there is a night shift and earlyafternoon shift). Both aluminum and brass and bronze are poured during theday and at night only one metal is poured.

Products: The company produces brass, bronze and aluminum castings. Theproducts include golf balls, faucets, and fire-hydrant nozzle rings.

SIC: 3362 Brass Foundry: Brass. Copper, BronzeAluminum Foundry: Aluminum

Operatio flS:The molding section:

Hunter automated molding machine , two manual moldingmachines , and a sand mixer.

The core room section;ten core machines

The melting section:furnaces and two melters.

The sand removal section:shakeout system , blaster (to remove small particles of sand)

The finishing section:eleven grinders

The company shuts down yearly in the summer for maintenance and clean up.This includes putting new parts in the machines and replacing conveyer belts.Sometimes the company may also shut down in the winter for maintenance.

1

Ill. Project Focus and Foundry Overview

The focus of this project was to reduce the green sand waste by

improving the process efficiency and improving the reuse of the sand. While

afl the sand-using processes generate waste sand, the green sand process

generates the largest volume.

The foundry uses three sand processes: green sand, air-set (chemically bonded

used for fine finishings on castings), and core sand. Molds are made from air set sand

or green sand. Cores and shells have a different chemical binder than air set. The

following chart shows the percent of the total sand used for each process

% white sand % brown sand

Green sand 26-30 90Air-set Sand 70-80 0Coresand 0 10

Total 100 100

Figure 1 provides an overview of the plant layout and also the work flow.

Areas where mixing, shakeout, mold pouring, and finishing occur are

identified

IV. Process Description for Casting with Green Sand

A. Overall Description

The sand is called green because only natural binders are used to form

the mulls (molds - see glossary for foundry terms). After the metal is pouredinto the mulls, the sand turns black. Once the sand is mixed. it is pneumatically

sent to the molding machines to form mufis. After the casting are poured, the

molds are then transported to the shake-out system. Part of the sand is

pneumatically moved to a silo to be later mixed with new sand for reuse. Part of

the clay burns out (calcination) causing a portion of the sand to become

For purposes of this report brown sand referes to silica sand ~ 135 and whIte sandrefers to silica sand 75

2

unusable. Consequently, this sand has to be sent to a special landfill because it

cannot be used as clean fill, although it is not a hazardous.vaste.

B. Complete Description of Individual Parts of Process [Figure II.

Mixing: The sand from the storage silo is mixed with “new” sand. clay

and water at the muller (sand mixer). The muller has a beater and a rotary arm

to blend the batch of sand. The clay binds the sand and the water increases the

binding property. The ‘new” sand is “white” sand which is silica sand of 70

grain fineness and Thrown’ sand which is silica sand of 135 grain fineness. Two

types of clay are added. The first is southern bentonite which is

Montmorillonite, Class 1B21 containing calcium ions. This clay gives higher

green compression; i.e. that property which holds sand grains together after

compaction (molding) to facilitate handling prior to pouring and also promotes

good collapsibility at the shakeout.2 The second is western bentonite which is

Montmorillonite Class IA containing sodium ions~3. This clay gives the mold its

hot strength; i.e. that property which holds the sand grains together during

pouring and solidification.”Testing at the Muller: After the muller mixes the sand, a ‘squeeze’ test is

performed. Depending on the “feel” more additives may be added or it is then

sent to the molding machines. A squeeze test is a subjective test. The muller

takes a handful of sand, squeezes it, and observes compaction and the amount of

moisture. Once it appears to be Ol~, the mixed sand is sent to a hopper under the

muller from which it is pneumatically sent to the molding machines.

Once a day, a methylene blue test is used to check the amount of clay in

the mixture by reading the adsorbance level of the sand sample. This test is

only performed on samples taken at the Hunters. the automatic molding

machines. There are no sand tests performed on the sand used in the manual

molding process.

IJ. Germ Sylvia. Cast MetalsTechnologv. (Reading, Massachusetts: Addisonn-WesleyPublishing Company, 1972), p.732 Application of Additives to Clay-Bonded Sand Systems p25

3Sylvia,p.734The Aoolicatioa of Additives to Clay-Bonded Sand Systems p.21

3

Figure One — PlantLayoutand Work Row

A~r Set

lump crushing process

tric Furnace Area

I I

u[’_Core Room Area

Raw Materj~ Storage

~1~D

C~een Sand Area

Melting

~1d H.~nd1ingAutomaticTiold Machines

I

~‘1o1dirf.~ M.~ohines

L~

a st I n q

Shakeout S!Jstem

Loading Dock

___ c~ ~

\\ ~ _______

‘.::=~~-~ ~# Whirley bird refers to the

__________ Finishing

-~ departments

\f~=~j \r~-=~i

4

Molding Process: Two molding machines are manually operated, one a

squeezer and the other a rotalifter, sharing a common sand hopper. The

manual molding machines are used for larger castings. The squeezer differs

from the rotalifter in that it is used for light weight castings5. Because themanual molding operations take longer, more water is added to the sand.

Usually the squeezer forms molds for one metal and the rotalifter forms molds

for a different metal ( ie. the squeezer makes aluminum castings and the

rotalifter makes brass castings).

Sand is also sent to two automatic molding machines called Hunters. One

automatic molding machine processes mulls for aluminum while the other for

brass. The mulls from the Hunters are sent. to an automatic mold holding

machine where the metal is poured. At night only one machine processes

mulls for the type of metal to be cast.

Once the molding is finished, the mulls from the manual molding

machines are conveyed to the shakeout system by pallet roller conveyers. The

mulls from the Hunters are sent to the shakeout system by automatic conveyer

belts.

Final Sand PaUi: The shakeout system is a conveying unit vhich

vibrates and breaks off the sand from the casting. Once the castings are

separated from the sand, the sand is further broken apart by a ‘~whirlybird. (a

lump crushing process which is a spiked grinder). This sand is then screened

through a 5 foot diameter 1/4 inch screen to separate out the cores/metals and

then pneumatically sent up to the silo where the sand which can be reused is

stored. As needed, the sand in the silo is then returned to a hopper above the

muller from which it can easily be incorporated into new batches of sand.

Weekly, the workers remove the shakeout sand which accumulates

under the conveyer belts and the shakeout system. This sand is sent to a landfill.The Differences Between Brass and Aluminum Sand Mixtures: Red Brass,

which is molded at the hottest temperature (2350°F), requires southern and

western bentonite clays to be added because it is molded at a hotter temperature

and the mufls need a stronger bond. Also since the metal is hotter greater

permeability of the sand is needed for the heat to escape. When pouring Red

5Clyde A. Sanders. Foundry Sand Practice (Skokie, llhinoiss:The American ColloidCompany, 1973) p.73

5

Brass the recycled sand becomes hotter. Therefore more water is added in

mixing the sand to cool it than if aluminum is to be poured into the sand mufis.When making mulls for brass castings (typically 1400 pound batches),

green sand is mixed with brown sand and white sand, with a small amount of

southern bentonite (depending on the green strength) and western bentonite

added to the inuller( the sand mixer).

Aluminum, however, is cast at I4OtYF. When recycled sand is used,

aluminum casts require mulls without the additional clays since there is

sufficient clay in the recycled sand. Occasionally, wood flour will be added to

mul.Is holding molten aluminum to allow the casting to expand without

collapsing the mull. The wood flour functions as a cushion to control the

expansion of the sand by burning out at elevated temperatures. 6

Therefore, as shakeout is not segregated for aluminum versus brass

moldings, its composition varies. For reuse, it should be noted that it would be

beneficial if sand was more homogeneous.

C. Description of How Process Fits into ComDanv’s Total Activities:

The molding machines form a “cope” and “drag” from patterns made of

wood or metal (Figure Two), The cope is the top part of the mull and the drag is

the bottom of the mold. These patterns are designed with gates and risers for

feeding the molten metal into the casting cavity. The riser compensates for the

internal contraction of the casting during solidification by maintaining a

stream of molten metal to the casting as it cools and contracts. It is much larger

than the casting and consequently cools slower.7 Depending on the casting, a

core or shell will be inserted inside the mull to make a cavity. A shell differs

from a core in that it has a hollow middle and requires a different chemical

binder. After the castings are formed, the remaining sand is removed and then

the castings are sent to the finishing department. The knock-out system

removes sand and remaining core butts by vibrating the casting, The

wheelabrater removes the remaining baked on sand by a shot blast method.

6 Sylvia, pp.78, 797Sylvia, pp,316, 325

6

Fk~ureT~

Cope end Draq of Mull with Gates end Risers

~~

Sand 1~~4c~

J Thi~,~Fr~-~Wt’j

tii~J )1t~~.ri-R~1r1~ ffi~Tf’~ft

~3 re ens and

Metal Casting

Core for viods in casting

Taper or padded section

Ri~er~ are the additional pieces of metal tofeed molten metal~ into the ca~ti nq~

Core

7

Finally, the gates and risers are cut off. If desired, the castings can be

smoothed with grinders.

V WasteSurveyflata

A. Products used in process; About 01% southern and western bentonite clay,

1% white sand and brown sand are added to each 1400 pound hatch of green sand

mixed from recycled sand. The monthly amount of brown sand and benLonite

purchased is 12.5 tons. During the past year. white sand purchases varied from

50 tons to 100 tons per month. The companies the products were purchased fromare given in Appendix 2.

B. Production Criteria; Casting samples are sent to the customer. If the

customer likes them, the company ships the order to them, but if the castings

are defective they have to be remelted. After the castings are made, they are

individually counted and inspected. The castings can have the following defects

from bad sand properties:

1) A buckle is a defect on a casting surface, appearing as an

indentation resulting from an expansion scab.

2) A scab is a blemish on a casting caused by eruption of gas from the

mold face.

3) A sag is a defect which appears as an increase or decrease in metal

section due to sinking of sand in the cope (decreased section) or

sagging in the core (increased section).

Some other defects not caused by bad sand properties include;

1) A shift is a casting defect resulting from a mismatch of cope anddrag.

2) The metal can age or not be melted at the correct temperature.

C. Production Levels; The company produces from 300 to 10,000 castings of

brass and 175 to 21,100 castings of aluminum a day. The production level

depends on the size of the part to be cast and the workday. A mull can form

more than one casting depending on the size of the part.

8

Production is limited mainly by the muller and the furnaces. The muller

mixes 1400 pounds of sand every 2 minutes if it is mixing automatically; manual

mixing takes longer. The automatic molding machines can produce 120 mulls

per hour maximum, but on average they produce 60 mulls per hour (where a

mull is 180 pound with dimensIons of 14” by 19” and a 4” cope / 5” drag). The

rotalifter makes about 7 mulls for each metal batch (a metal batch consists of

2.000 pounds of brass which takes 45 minutes to melt in the induction furnaces,

and 600 pounds for aluminum which takes 45 minutes to melt in the gas fed

furnaces).

D, Waste Stream Related to Green Sand Molding Ooerations

The area underneath the Muller and next to the hoppers contains mostly

burnt clays and fines. Accumulated fines are vacuumed out. The area

underneath the conveying system which is dug out weekly contains some fines,

but the majority isgreen sand from the mulls. This material is reusable.

Samples of waste sand from the mixing and conveying system were taken as

well as new sand. Pictures of the sand grains are shown in Photo 1. Appendix S

provides information obtained in characterizing the sand coming from the

mixer and that from the silo.

I. Waste description

The clay burns out more when brass is poured then when aluminum ispoured. Calcining is the process where the clay is burned off at temperatures

equal to or greater than 10002F or lost through a mechanical process. It should

be noted that once the temperature of green sand rises above 1200°F. the

deterioration of its properties also increases, especially that of compression.

Also if the sand has less than a 3% clay in water content, calcining occurs at an

increased rate above 1000°F.

As the sand is continuously recycled it also becomes smaller due to the

frictional forces and becomes more spherical instead of angular. Angular sand

is more desirable for green sand casting since there is more packing space for

clay. This also improves its molding ability in manual molding machines.

9

New Brown Sand [1

4

• -

Photo 1~

1

-Cai

New White Sand

I]I

Sand From Conveying System 10 Fines Found by Whiny Bird

If excess water is added in the muller, the castings become deformed due

to water evaporation. To prevent this, molders may discard hoppers if sand theybelieve contain too much moisture. It should be noted that the evaluation of the

molder is subjective, which may mean good sand is dumped.

2. Total Non-Hazardous Annual Waste Sand

Poor Richards picks up the company’s waste weekly. This waste not only

contains greensand, but also contains air-set sand, cores and other foundry

debris. The green sand represents approximately 45% of the total waste sand.

3. Current Management for Wastes~The night shift digs the sand out of the pits located underneath the

conveyer system and shakeout weekly. They also remove the sand underneath

the muller every two to three weeks. During shut down in the summer, the roof

is swept of fines. Waste collection from different areas is depicted in Figure 3.

VI. Ootions for Reduction of Waste Sand

A. Overview

The American Foundry Society’s Technical Committee has developed a

summary of function requirements for a sand reclamation system. Appendix 3

provides their function requirements. This committee’s recommendation is that

the whole process must be addressed if a company is aiming to successfully

reclaim green sand.

Reclaiming green sand in a small aluminum and/or brass foundry

requires different considerations than a reclamation system for a chemically

bonded sand system or for reclaiming green sand from a small ferrous (steel)

foundry. In a brass and aluminum green sand process. there is a lot of active

clay left after shakeout which adheres to sand that is continuously reused. In

ferrous foundaries less active clay is left due to calcination. Therefore, an

attrition system is required to remove the inactive clays for reuse in the ferrous

process. In chemically bonded sand the binders must also be removed to be able

11

~ure Three Areas Ger*raUn Green Sand Waste

Large Hopper = 3500 Lbs.Smal 1_Hopper = 1 400 Lbs.

1 2/3 Large Hoppers

1 Large Hopper

Molding Machines

• .

• • ~—. ....

• • ‘~“::~

~ST~kê~~~dergro&ind)

~ : : :•-- •

‘i~rbr1y8ird -

MeltingFloorArea

RoofS ~. S •S % ‘~‘.‘.~, , f_ _ _ — , — , —

S. ‘~ S.~S. S. S. S. S. S. S., _ _ ,, , _ _ , , , _

S. ~• •S~~ % ~• •5 ••~ S~— .. _ ,_ ,_.,( , — _ ,%%S.~.S.J hsS.S.%/ .•#/ .~ 1// , , , , ,

sS.%~S.% AS.S.S.S.~~__,,__ .•___/_

S.\%S.~S.S. %\\%~~~_ _ _ , ,_ _ _ / _ , , — _

•. S. S..S. %S.% ‘5’.’,’ S. ‘S•.? ~‘ .‘ .‘ /‘4 ..C — .‘‘ ‘. “ ‘ ‘. •‘~~ ~ i’i r. ‘~ •.

..• — , _—~, , ~, — / /S. %% S. S •. ‘~ •~ %

sand from silo and baghouse

A drg gear accumulates 3 Larqe Hopper3A ~~‘et ~e~r eccumul~te~ 4—5 Large Hopper3.

‘S.’

‘‘5’

Auto Molding Machines

Mo] dHandling

Co n~ eye rs

Shakeout

2 Large HoppersEmptied~ times a ~weqk

LargeAccumulations

Small HoppersEmptied 1 —2times a year

5 Small HoppersEmptied ‘~‘eekly

1 Large HopperEmptiede’ier’j year

12

to reuse It. The goals in reclaiming green sand are:I. To remove calcined clay and still retain’ the maximum amount

of live clay left in the sand.

2~ To fully particulate the sand.

3. To provide a sand which exhibits a consistent temperature.4. To remove all remaining agglomerates or particles of a non-

silica nature( magnetic and non-magnetic)8

To recycle or reclaim green sand the whole system must be looked at.

This includes: 1) the muller2) mold pouring and cooling zones 3) shakeout 4)

return belts and elevators 5) screens, bins, hoppers and prepared sand delivery

6) molding machines9

One piece of equipment will not solve the problem. The whole process

from the mixer, pneumatic systems, molding machines, conveyor belts,

inventory procedure, and sand testing procedures needs to be looked at. By

making each part of the process more efficient, a higher green sand

percentage can be reused. It should be noted that a ferrous foundry on the west

coast has put in a reclamation system which recovers 98% of the greensand.

B. Areas for reductions at the foundry.

Process areas are identified for changes to reduce the waste sand there.

It should be noted that Appendix 4 provides an expanded source of information

regarding available equipment or ideas for equipment or process change. Insome cases, sand losses would be effected in more than one area.

Areas with suggestions for change at the foundry are identified below.

1. SandMixingandTesting

Area:

1) The mufler mixes according to a feel test which does not test the sand

properties. Often too much water is added, resulting in bad castings and

lumpy sand.

8AFS Transactions p. 14 “Combined Cooling, Reclamation, and Particulation forImproved Green Sand Performance’ Jerry V. Kucharczyk. Dieter S. Leidel p 2109AFS Committee Report: “Sand System Functions-Requirements and Specifications.’ AFSTransactions pp 209-216. (1980) 13

2) Daily sand testing is performed only on samples taken from one of

the Hunters. Only one testing is taken per day while sand is beingcontinuously mixed throughout the day. This often results in poor sand

mixes which then means defective molds are poured.

3) Also, the muller receives the results hours alter the sand has been

delivered. This may result in more bad batches of sand beingmixed since

the muller is not given information in time to adjust the mixing process.

4) The sand properties during the time of delivery and use may also

change while it is held in the molding areas storage hoppers. This has a

greater chance of occurring on extremely hot days.

Solution:

1) A more accurate testing.procedure is needed.There is a sand monitor

connected to the muller. The tester does not operate correctly as it was

not installed correctly. The sampling device hits the beater when it

takes a sample. This system also does not function properly as the sand is

not homogenous. The tester would take various readings of the sand by

light sensors. Its use was discontInued since it caused too much water to

be added to the mixes.

2) A more comprehensive testing program would reduce the number of

bad sand mixes produced.

3) A faster turn around time on the testing results would assist the

muller in adjusting the sand mixing to ensure good batches.

4) More closely mixing the batches with the time-frame for use willhelp prevent a change in the sand properties as mixed sand waits to be

used.

2. Automatic Molding Area

Area:

Overloading of the conveying system results when a bad batch of sand

(either too wet or dry to be used) is batched dumped. Since the

conveying belts can not handle the load all at once some sand falls into

the trenchs underneath the conveying system and ultimately ends up in

the waste sent to the Landfill.

14

Solution:

1) Devise a mechanism to control the feed rate from the hopper onto theconveyor belt.

3. Conveying BeltsArea:

I) Sand is also lost from the conveying system due to worn belts which

cannot hold as much sand because their width has been reduced.

Currently, belts are changed about every two months.

Solution:

1) A maintenance program should be established such that belts are

replaced when there is any noticeable charge in belt width

4. Pouring

Area:

1) The poured metal inactivates the clay closest to the metal. Also the

brass and aluminum are poured at different temperatures the clay burns

out at different rates. This means the shakeout sand’s clay content,

moisture content and temperature vary.

2) The size of the castings will also cause the sand properties to vary

since the burn out rate is dependent on the metal to sand ratio. For

example, a large casting will have a higher calcination rate than a small

casting since the metal comes in contact with a higher percentage of the

surface.

Solutions:

1) Schedule similiar sized castings to be poured at the same time so the

calcination rates on all the used sand is similar.

2) Improve the mixing of the used sand so that it exhibits more

homogenous properties prior to sending it back to the muller.

3) Add a reclamation system which would provide a hornogenous return

sand in that it would remove the inactive clays, cool the sand and dry it.

15

I

5. ShakeoutArea

The present shakeout system leaves large lumps and small pieces of core

in the return sand. This is due to two factors:

1) The system becomes overloaded when the castings from the manual

molding area are placed on the shakeout system. Generally, because of

the time constraints, they are placed into the system at the same time

instead of one mull every few minutes. This type of overloading alsocauses the hopper which feeds sand from the screen to the silo to be

blown openn. The hopper is limited to 15 cubic feet.

2) In addition, the area where these castings.are fed into the shakeout

system is close to the screen. Since these castings are generally the

larger ones, there is less time to shakeout the sand and cool it.

Consequently. the lumps go past the screen, reaching the silo along with

wire, metal and core pieces.

Solutions:

• 1) Place the casts from the manual molding area onto the shakeouut at a

uniform rate.

2) Extend the length of the shakeout area prior to the shakeout screen

for the large castings

3) Improve the lump crushing efficiency of the whirlybird.

6. SiloArea:

1) Lumps in the return sand system hold in excess moisture and

temperature. The silo is constructed with brick walls which allow the

moist, warm sand to condense on to them. This means the return sand is

used on a first in, first out basis in which the sand grains break down

faster. The silo’s walls are scraped on a yearly basis but this only

alleviates the problem slightly. More efficient use of the return sand

will reduce the amount of new sand needed and the volume of waste sand

generated.

16

2) During the projects an effort was made to determine wall buildup

versus free sand ratios in the silo. The buildup observed was on one foot

one side of the silo and three feet on the other side of the silo. With this

kind of build up, only 52% of the sand is available for use, while the

remaining 47% builds up on the silo surface. (Calculations used to

determine these percentages are shown in Appendix 5)

Solutions:

1) Divide the silo into smaller bins and insulate them. This was found to

work in another foundry.

2) Use a mechanical system to remove the accumulations on the wall on

a continuous basis.

3) Use an epoxy coating or sealant to prevent the sand from sticking.4) Use of a reclaimer or sand cooler to treat the sand prior to storage.Lists of the types and contacts for this equipment can be found in

Appendix 4.

Vu. Evaluation of Sand Waste Reduction Potential in Process Operation

While all of the areas above need to be addressed, Table I is provided as a

mechanism for the foundry to use in evaluating priorities for change. It should

be noted that all rankings in the table are subjective. This table summarizes theestimated effect of change on the wastestream volume, the relatIve cost of

implementation and the ease of implementing the option.

17

Table 1

r!W3stestre3m Volume

* Ranking provided by Lisa Monsour. intern student, based on

observation, information collected from people in the plant, as will as eople

outside but familiar with foundry operations.** Ranked high because of sapce limitations at the company

Peiative(~st E~seo~ mplernent~t~on~nd Testing Low Low Me~iium

Mr~er Im~rovemerit r1e~jium M€~jium—Higfl Medium—Hrnr~( ~.e. probes.)

~ E~tch Dumpint~ Prcci~dures tledwm Low Medium

~ Production Schedule Medium Low Medwm

~ ~n3k.eour High t1’3diurn-Hi~ri

~ Fines Remov& Medium—High High *High

~ 3ilo Medium Medium—H~h Medium—High

18

Viii. Other OptIons RevIewed

The following equipment was investigated this summer whileobserving the production proccess in hopes of improving the system. These

possihiities where not further researched because it was found that the

equipment would not improve the processes at the foundry.

A. Vacuums

Another way to pick up fines is to vacuum the fines. While observing

one of the workers vacuuming it was seen that the vacuum would plug up and

he would have to climb up and bang on the tubes to unclog the sand

(Therefores, shoveling the sand from the pits appears to be easier.)

B. Screw Conveyors

While watching the shoveling of sand from the pits, an attempt to come

up with an easier way to remove the sand was tried. The suggestion of screw

conveyors was made. This was checked. While talking to a salesman, it was

found that the conveyors would not be useful. The pits are now shoveled onto

the conveyors and the sand removed in the shakeout area. With a screw

conveyor, a bin would have to be lowered down into the pits and the workers

would still have to shovel the sand into the bins. The screw conveyor would

then bring the sand from the pits and feed the sand into a hopper.

19

BiblIogr.phy

*AFS Committee Report “Sand System Functions - RequIrements and Specifications,”4/3’ Tnin~ictAwspp 209- 216, (1980)

AFS Publication, Sand Reclamation, Des Plaines, Illinois, 1986

American Foundrymen’s Society. Ed. Industrial Engineering in the Foundry, DesPlaines, Illinois: AFS Inc. 1963, 1974.

American Foundryrnen’s Society.Ed. Mold and Core Test Handbook, Des Plaines, Illinois:AFS Inc. 1980.

*Braiower P.M., and Burditt MI. “Is the Profit Line the Bottom Line in SandReclamation?’. Modern Casting Vol. 78 No. 5, (May 1988) pp. 27-35.

Dietert, H.W. “A Sand Control Program that Saves Lives”, AFS Transaction 1974, pp.74-86.

Dietert H.W. Processing Molding Sand. Des Plaines Illinois: AFS 1954.

Good, George, ET AL. and AFS Sand Reclamation & Reuse CommIttee. Sand ReclamationDes Plaines, Illinois: American Foundrymen’s Society, Inc., 1987.

‘Kucharczyk. Jerry, Leidel, D.S., “Combined Cooling. Reclamation, and Particulation forImproved Green Sand Performance”, APSTransaction..c ppl3-2O (1988)

Lawson, D. S. Leidel: “Reclaimed Shakeout, Sand as New Sand Substitute in Green SandMolding Lines,” AfSTraasaciion., pp 1-6 (1984)

Northwest Olivine Company. Olivine Asiregra*e in the Non-Ferrous Foundry. NonFerrous Foundry’s Society, October 1960.

Rowley, Mervin T., Casting CooDer Base Alloys. Des Plaines IllinoIs: AFS, 1984.

Sanders, Clyde A. Foundry Sand Practice. Skokie, Illinois: American Colloid Company,1960, 1973.

20

Sylvia. J. Germ. Cast Metals Technology. Reading. Massachusetts: Addison-WesleyPublishing Company, 1972.

References that were found to be particularly helpful during the project

21

Appendix 1

GLOSSARY

Air-set(No Bake)- Molding sand made ‘with silica sand of 75 grain fineness and achemical binder( phenol or oil)

casting- for this project castings are brass, aluminum, or cuppercope- the top part of the mullcore- an insert placed in the mull to form a cavityCore sand- sand forming a core made with 135 silica sand and an oil binderdrag- the bottom part of the mulldross- Metal oxides, etc., on or in a metal or alloyGreen sand- molding sand made ‘with silica sand of 75 and 135 grain fineness and

western and southern bentonite claysknock-out- vibrator for castings to remove core butts and more sandmull- the mold formed from the sand mixture

uller- sand mixer for greensandpattern- a wood or metal form that has the desin of a particular casting for the sandriddle- Hand or power operated device for removing large particles of sand or foreignmaterial from boundry sand.rotalifter-a manual molding machine for mulls not put on Hunter automated molding

machines V

sand typesOlivine- Sharply angular with high thermal compacity and in lowertemperature ranges a high thermal conductivity. This sand gives asmoother finish.

Silica- Fusion point of greensand is 3250’ F and the fusion for clay is2400’ - 2500’F10

Zircon- High refractory value, conductivity, and density, with a lowexpansion level. The expansion is less than one-third of silica sand. Themelting point is 4000’ F.11

slag- nonmetallic covering on molten metal as the result of the combining ofimpurities contained in the original charge. such as ash from the fuel, and any silicaand clay eroded from the refractory lining. Except in bottom pour ladles, it is skimmedoff prior to pouring the metal.sqeezer- a manual molding machine for mulls not put on Hunter automated molding

machines

vhoelabrstor- machine which shoots lead shot onto casting to remove final sand oncasting V

t0Clyde A. Sanders, foundry Sand Practice American Cofloid Co., Skokie, Illionois pp. V

63.661CIyde A. Sanders, Foundry Sand Practice American Colloid Co., Skokie, lllioñois pp.

66-67

22

SAND AND CLAY SOURCES

Trade Name Chemical Source Supplier Transporter Amount Frequency Cost StorageMake—up Purchased of Purchase

“White Sand Free Silica Connetiout Unimin Transportation Bay 25-27 tons weekly $1 0.4/ton siloOranusil (Crystalline) 258 Elm Street outside of foundry

* 75 Silica Sand (Quartz) New Canaan

Conn. 06840

“Brown S.nd Free Silica Badger Mining 25 tons ery 2 month:$48.30/ton siloGranusli (Crystalline) P.O. Box 97 outside of foundry

~ 135 Silica Sand (Quartz) FairwaterWis. 53931

Southern Jlontmorillonit Alabama American Colloid Co. Carpenter Brothers 1 .4 tons every month on palletsBentonite Class 18 MissIssippi 1500W. ShureDrtte (100 lb bags) by muller

Arlington He~htsIll. 60004

Western ?lontmorillonit Wyoming — Carpenter Brothers 1 .2 tons about everyBentonite Class 1 A South Dakota (1 00 lb bags)other month

Montana

r r r [

AFS FUNCTION REQUIREMENTS OF GREEN SAND RECLAMATION SYSTEM

Function Requirements

1) Shakeout

Shakeouts are sized to carry the anticipated peak load in sand~1 and castings and usually are a compromise. The compromise is

between the energy, time and impact required to effect completeseparation of sand from casting, and minimization of castingdamage and energy requirements. Requirements of the casting

~ should be paramount. Weshould notsavetimeinseparatingthesand from the casting by damaging the casting with violence orin compromising casting quality by adulteration of the sand.

Control observations are required before shakeout and- 1 consist of mold identity, weight and type of cores and weight of

metal poured. Compensation for the thermal load or weight ofmetal poured can begin at the shakeout.

2) Reblending

All the fractions of sand that result from producing and shakingout a mold should be gathered and blended together withrequired new sand and bond additions. These fractions arecalcined sand, dried, loose sand, dried lumps, spill sand, corebutts and core breakdown sand. In addition are the fines drawnoff in dust collection.

The reblend quantity should be a weight multiple of the moldsproduced and mixer batch size: ten(l0) molds or five (5) mixer

batches. Sufficient water should be added it required to preventloss of fines to dusting.

3) Cooling

Cooling should be close to ambient temperature. A practicallower limit of temperature should be selected. The maximumtemperature permissible is set by sand properties (compactability) at 43C (IIOF). In cold climates, sheltering or insulation ofbins may be required to prevent vapor transfer to bin walls andsubsequent clogging of bins.

4) Rubble Removal

[ron spills, core butts, wires or anything that is not granular free-flowing must be removed from the return sand and eitherdiscarded or reprocessed.

5) Discard and Replacement of Sand

The dilution requirement of 300 pourtds of sand replacemenc(toinclude disintegrated cores) for each ton of iron cast may be asafe overstatement: it may also be costly in that it generates bothreplacement and disposal costs. Reblending of sand and newsand additions based on the net of core disintegration and tonscast in a given amount of system sand are a requirement for sandstability and economy.

6) Replacement of Clay

As with sand, a replacement rate of clay to reblended sand mustbe based on clay deterioration and the sum of core disintegration and new sand additions according to tons cast in a givenamount of sand. A conventional quantity is 54 pounds per toncast or 27 kg per tonne cast. With adequate control andreblending. additions of sand and clay may be adjusteddownward.

7) Stabilization of Return Sand Moisture

The moisture levej is not absolute but depends on sandcomposition, so the stabilization should be in terms ofcompactability. The minimum compactability to prevent loss offines to controlled dust collection appears to be in the range of22 to 23. Return sand moisture should be stabilized to be aminimum compactabilicv of 24 and maximum of 30 to be free-flowing.

8) Storage in Free-Flowing Bins

All scorage bins should be designed to be first-in, first-out and todischarge at a fixed controlled rate.

9) Precise Metering of Sand to Mixer

The weight of sand added to the mixer must be closelycontrolled so that the addition of water can be programmed.The sand weight tolerancerequiremeat is ± 2.0%.

10) Precise Water Additions to the Mixer

The preprogrammed water additions should be controlled to±0.1% water addition, and the compactability controlled to.±2.5%.

11) Precise Input of Energy Over Time to the Mixer; i.e..Mixing

The mixing cycle must satisfy sand grain contact-frequencyrequirements and the mixer output must satisfy molding raterequirements. The mixers must be sized with power to satisfymaximum molding tates. The system must be designed so thatthe mixer operates constantly at a predetermined schedule. Inorder to do this, the output must be adjustable to correspond tothe molding rate and there must be prepared sand surge storagebetween the mixer and molding machine so that sporadicinterruption of the molding rate will not affect mixer operationsand control. Energy requirements can vary with mixer designand sand requirements. The variations for a given mixer andsand composition should not exceed ± 6%.

12) Delivery to the Molding Station

Sand delivery to the molding station should be consistent withboth the molding rate and mixing rate which must be equal.Consequently, this delivery rate must be adjustable withinlimits. The supply hopper must be designed to prevent pre.compaction of molding sand by impact from dropping. Thesupply hopper must also be designed to deliver a predeterminedweight of sand to the flask prefill hopper with a variation byweight of no more than 3.0%.

There is an overall requirement that functional controls andenvironmental controls for such as dust suppression and orcollection be mutually reinforcing and must never be opposed.Ventilation must be designed to be noncondensing under alloperating conditions and fines must be recaptured for reincorporation. The fines must be sampled and qualified beforereincorporation.

Sand Control System

The twelve essential functions are combined into a unifiedsystem together with several secondary functions or sub-processes as shown in a sand system sequential flow diagram.Fig. I. The system will be under the control of a microprocessorwhich will gather real time data on the mechanical, electrical,physical and thermal state of the system. This data is to bereported to sand system management and to maintenancemanagement. The processor will internally compare the systemstates to standard state and identify both variances andmalfunctions.

The subprocesses of normaiization will reduce variances toless than 20% of the current mean at 99% confidence: Theconditioning subprocesses will bring system means to within10% of target means. Final programmed adjustments will be towithin tolerance requirements.

R.S. Lee, “SAND SYSTEM FUNCTIONS: REQUIREMENTS AND SPECIFICATIONS,” AFS TRANSACTIONS,~ 91’~_~1~ (1OQn~

AppendAz 4

Process Equipent and In-House Changes

Note: All information regarding vendor equipment in this appendix was takendirectly from the vendor literature. In some cases, quotes are included fromvendor literature.

Shakeout

A. Lump Crushing Process1 )Molder’s Friend

Method of operation: Is a piece of equipment whichs uses amechanical aerator to mix and fluff the sand. The unit could be placedafter the whiny bird but before the screen to reduce the lumps and coolthe sand.

Contact: “The Molders Friend, Inc.”BergmeierDallas City. 111. 62330(217) 852-3525

Other: The Molder’s Friend was considered before this project startedThis is a relatively inexpensive piece of equipment which can be leasedwith the option to buy.

2) Hartley Series 2800 Metal Separator SystemMethod of operation: This system reduces sand lumps to fine grains. Theshakeout sand goes into a bin. The sand is then fed into the separatorwhere the sand is screened through a 10 mesh screen. This systemprevents riddling.

Contact: Home Brookfiend WisconsinHartley Engineered Control SystemsRichard P. RoheGeneral ManagerHolly RoadNeenah, Wisconsin 54956

Hill and Griffith-Hartley Engineered Control Systems.Don ShroederRegion SalesmandCincinnati. Ohio 45204(513) 921-10

Approximate cost: This system costs approximately $28000.

25

3)RoflerMethod of Operation This system would break up the lumps after thewiny bird. It would consist of a series of rollers in which the sand wouldbe crushed between the individual blades. A design is beinginvestigated by the foundry staff.

4) Whiny BirdMethod of Operation: Improvements in the lump current crushingprocess can be achieved be adding a second whiny bird in series withthe existing unit or adding more spikes to the existing unit.

BShakeoutSystems1) Didion Rotary Sand Casting Seoarator

Method of Operation: Poured molds are delivered into the intake end oftherotary drum. As the molds tumble through the drum, the sand isseparated ffom the casting, crushed to grain size, and dissipated throughapertures in the lining to the outer chamber, where it is conveyed to thesand discharge point. The cleaned castings travel to the castingdischarge end of the cleaning room.The tumbling action in the DIDION crushes sand lumps, removes corebutts, and empties sand pockets. The apertures in the patented lining actas a rotary screen to prevent tramp metal, core buus, and other foreignmaterial from entering the sand system. Moreover, the sand ishomogenized and uniform in temperature, since cooler sand from moldsentering the DIDION is constantly mixed with hotter sand as it passesthrough the lining into the sand chamber. This alloys for better sandcontrol at the muller.’

Contact; Didion Manufacturing CompanyP.O.Box177Patmos CourtSt. Peters, Missouri 63376(314)928-1940

Approximate Cost: The unit including a 1/4°’ screen would beapproximately $30,000.

Other: The Didion system would cool and separate the sand. It could beused in place of the current shakeout system. This system may beinvestigated futher in the future.

2) Vibra-MiJI VMCMethod of Operation; A low volume air flow, diffused into the mAilthrough slots in the breaker teeth, maintains cooling of sand grains aslump breaking takes place. Efficient heat removal is obtained bycombining air turbulence with sand tumbling action. Warmed air isvented to an overhead exhaust hood. Cooled sand moves through sizingscreens to separate tramp material and °‘fines,’ and is discharged fromthe Vibra-Mill with original grain size distribution and correspondingreduction in L.O.I.

26

Contact: General Kinematics CorporationLake Zurich RoadBarrington. IL 60010(312) 381-2240

C. Comparison of systems

Unit Size CostDidion medium yes expensive 314’-l/4’Hartley inediwn expensive 10 meshVMC too large grainsizeMolders Friend ok reasonable

Sand Testing

A. Process FunctionAutomatic testing equipment could control the sand mixes so that overly moistsand would not get into the system. This would improve the consisitency of thesand batches and produce better castings.

B. New Equipment1) Hartley Series 18-PC

Sand Controller for Batch MixersMethod of Operation: Probes mounted in the batch hopper send signalsforreturn sand moisture and temperature to the analog section of theprogrammable controller. These signals are instantaneously integratedcomputing the amount of water required. The controller then counts thenumber of pulses from a pulse transmitting water valve and shutsthe valve off at the correct amount of water, Changes in analog sectionvalues can be easily made should different compactability may berequried.”

2) Hartley Series 2300-Sand MonitorAutomatic Compactability TesterMethod of Operation: ‘This unit takes continuous compactability readingand “talks” to the analog section of the programmable controller. Whencompactability deviates from a specified range, the values in the analogsection of the programmable controller are automatically changed tobring compactability back into range”

3) Eirich Rotocontrol RO 200Method of Operation: ‘Typically installed over the prepared sand beltconveyor, the Rotocontrol monitors three properties of the preparedsand (namely:compactability. shear strenght, and compressivestrength). It can take up to 4 samples per minute. While it is currentlyused as a monitoring device, the rotocontrol unit can play a mostimportant 8 part in the future foundry by making possible ongoingfeed-bake control.”

4) Eirich SandinasterMethod of Operation: “Process control software package will futherenhance the modernization of a foundry operation.’

27

5) Eirich Moisture CompensatorMethod of Operation: “Temperature-compensated probe which isdesigned for mounting on the dust hood of the sand mixer. The unitworks on the dielectric constant principle, submerging into thehomogenized dry sand mass during the dry mixing phase. The measuredvalue can be used by the control system to calculate the required amountof water addition.”

C. New Equipment ContactsEirich Machines Inc.Applications EngineeringP.O. Box 1064Uniontown, PA 15401(416) 832-2241

Hartley Controls Corporation2400 Holly RoadNeenah, W1549561-800-634-5714

D. Used EquipmentThe former Minneapolis Electric Steel Casting Company has a green sandreclamation system for sale (the current company. Steel Preps. assemblescranes.but no longer casts the parts).The four cell reclaimer could easily handle the sand capacity of the foundry butthe unit is twenty four years old. In addition, the relaimer is large (4 feet wide,15 feet high and 12 feet long). The unit may require too much room for SaintPaul Brass. The used unit is selling for $5400.

E. Used Equipment ContactsVern JohnsonSteel Preps5th Street N. E.Columbia Heights, MN(612) 731-2761

Coolers

A.Processes1) Pangborn

Method of Operation: This system is basically a heat transfer process.The introduction of air through a porous membrane causes thereclaimed sand to become fluid. In this state the sand passes over andaround a series of water-cooled heat exchange tubes. The sand-heatedwater then passes to an evaporative tower where the water temperatureis reduced and reused in the cooling system. The cooled sand is placedback into the system.

28

Contact: The Carborundum CompanyPan gborn DivisionBox 380Hagerstown, MD 21740(301)739-3500

2) Simpson-National EngineerinaMethod of operation: This unit’s operation is similiar to the Pan gbornsystem. This is another piece of used equipment that Steel Preps isinterested in selling. The unit is nineteen years old. The unit mayrequire too much space for the foundry (9-10 feet long, and 8-10 feetwide). The selling price of the unit is $6,500.

Contact: Vern JohnsonSteel Preps5th Street N.E.Columbia Heights, MN(612)781-2761

B. In-House IdeaThis idea would involve placings a mechanical aerator after the winy bird andraise the sand feed before entering the screen feeding air form their 300 Hpsupply to cool sand.

Air Classifiers

Most of the green sand is being thrown away because of a build up of fines and alack of storage space in the silo. An air classifier would pneumatically separatethe fines from the larger sand grains. Its operation is similiar to a dry cyclone.Air and sand particles are blown into the classifier where the partides passthrough a centrifugal force, Large particles leave through the bottom of theunit and are fed back into the sand system. The fines are collected in a dustcollector..

Contacts:Alpine American Mineral Processing Systems, Inc.Michigan Drive Edward H. WipfNatIck, MN 10760 . Sales Coordination Manager240 Arch St., P.O. Box M-312 York, PA 17405

(717) 843-8671Ashley Mechanical, Inc.(914)331-1652

29

C.E. Raymond MikroPulCombustIon Engineering, Inc. Hosokawa Micron Internation Inc.Kevin C. Jenson Carol LandesmanApplication Engineer Administrative ClerkLisle, Illinois 60532 10 Chatham Road.(312)971-250 Summit,NJ07901

(210) 273-6360

Fisher-Kiosterman StutevantP.O. Box 11190,StatIonH Boston, MA02122Louisville, Kentucky 40211 (617) 282-0776(502) 776-1505

PraterS. 55th CourtChicago, Illinois 60650Clayton StreetTelex: 28-4312

Reclaiers

A. Pneumatic UnitsI) Simoson Pro-Claim

Method of Operation: This reclaimer reduces sand lumps by mechanicalmeans. It has four cells which shoot sand pneumaticlly at a large metaltarget. This process causes the sand to impinge upon the target andother sand grains scrubbing off the binders. The process is repeatedfour times as it moves through the four cells. The fines are collected in adust collector. The clean sand is returned to the system. This unit wouldalso cool the sand.

Contact: National Engineering Company

1716 V. Hubbard St.P.O. Box 6369

Chicago, IL 60680

(312)782-6140

B. Mechanical1) Rotocondit.ioner III

Method of Operation:Sand is fed into the impellor area and mixed in the attrition zone. Thematerial then passes through the scrubbing zone which is basically apneumatic system. Again the fines are collected in a dust collector whilethe clean sand is returned to the process.

Contact: Pan gborn CompanyP.O. Box380

30

Hagerstovn, MD 21741(301)739-3300

C. Thermal1) Mini-Model 1224 Sand Reclaimer

Method of Operation This unit operats on the rotary kiln principle. Afterthe sand is calcinated in the burning unit it is processed in a rotary aircooling chamber, screened and classified.The fines are collected in a dustcollector while the clean sand is returned to the system.

Contact: Coreco (College Research Corporation)N116 W16800 Main St.PO.Boz577Germantown. WI 53022(414) 255-4700

2) Thermo-ClaimMethod of Operation: This unit also operates ona modified rotary kilntype principle. This unit would be placed in series with an attritionsystem.

Contact: Whirl-Air-Flow Corporation1515 Central Ave. NEMinneapolis, MN 35413(612) 781-3466

Air Filters

Information on air filters was found while investigating the possiblity ofmodifying the current pneumatic sand transportation system to remove thesand fines. This did not turn out to be a viable option. Since the contacts may beof some, use for dust control.or other projects they were included in this report.

American Air Filter1103 V. Burnsvifle PkwySuite 102Burnsville, MN 33337(612) 894-0097

General Resource Corp.201 Third St. SHopkins, MN 55343(612) 933-7474

()uickdraft Corp.1325 Perry Dr. SWP.O. Box 1353-Station CCanton, OH 44708(216) 477-4574

Anderson-Cran Co.P.O. Box 50817

Buhier-Miag, Inc.P.O. Box 94971100 Zenium LaneMinneapolis, MN 35440-9497(612) 345-1401

Monroe Environmental Corp.IlPortAve.Monroe, MI 48161(313) 242-3273

Walsh Manufacturing Corp.13825 Trisket.tRd.Cleveland, OH 44111(216)231-6400

Crown Auger Mfg., Inc.Hwys l2and 137

31

Fort Worth. TX 76105 Cokato, MN 55321Mpls. Number: (612) 332-0331 (612) 286-5581

Falcon Industries, LTD Process ContEol Systems106 South Main St. 3947 Meadowbrood Rd.P0. Box 447 Minneapolis, MN 55426Hector MN 55342-0447 1-800-328-0738(612) 848-6681

32

Appendix 5

Sand Characterization and Silo Utilization

Calculation of the Percentage of Sand Reused from the Silo.

The percent of sand reused from the silo was determined based on areacalculations. The values used for the calculations are as follows:

Silo Dimensions: Range of Sand Thickness: l’-3’Diameter 10’ Average Thickness: 2.25’Height 20’Size of Brick 8’ Note in formula BS = Brick Size

Formula:

Area of = PI(Radius Silo-0.5 BSY2 - PI(Radius Silo-0,5 Ave. Sand Acc.-0.5 BS)’2Sand Acc.

= PIt(8.66/2)~2-(8.66-2.25/2)~21= 26.63 ft’2

% Sand = Area of Silo - Area of Sand Accumulation on Silo WallsReused Area of Silo

P1(8.66/2)~2 — 26.63 ft’ZPl(8.66/2)2

= 53.2%

Characterization of Sand from Silo:Four sand samples were taken from the silo when it was emptied and the wallswere scraped. Samples 1 and 2 represent the loose sand as it initial came out ofthe silo. Samples 3 and 4 represent samples taken from material scraped off thesilo’s walls. The results are as follows:

SamøleParameter 1 2 3 4 Ideal

ResultsGEN 90.78 100.81 87.44 93.57Clay(%) 6.2 6.6 over 7.6 7.2 6.2-7.0

Green Compression 13 12 18 - 22Compaction(%) 10.5 10.02 53 55 500pt.Efficiency(%) 2.6 2.43 38.Mix Efficiency(%) 34 58%Moisture 7.7 5.8 2.8-3.2PermeabilIty 9 12 48 - 52

33

GIN = Grain Fineness Number which represents the average fineness of the sandgrains in a sand sample and can be of some use In comparing sands.

MB = Methylene Blue provides some measure of the active clay in a- sand sampleS It canalso provide some guidance in sand mixing.

34

r r r r i 1 1