Document BRZykexJmoQ5ppxMX4G799r2m

December 30, I96A To: J. A. ilcI ley I From: R. A. Oicich >' ;w ' ~; I Subject: Report cn Oust Control at Libby Operation I PLAINTIFF'S j EXHw (1 WRG-435 iil: ' The Reich Rotary drill is a source of high dust concentration. Prior to the purchase or ci:o rotary drill, it v:as possible for the operator of the Joy Drilimohile to stand clear or the dust created by the pneuinatic hairocr. This is r.ot posable with the Reich drlil. The Reich drill was originally equipped with cn;y a centrifugal fan, collection hood anc cyclone. This system was inadequate and a liquid dust control system was installed end is new in use. A controlled quantity of water is usee during drilling tc- sup press the dust. During the freezing weather season7 Diesel fuel is substi tuted for the v.*c:er and works equally as well. The system is adequate. , The Euclid trucks pulverize the top surface of the main haul roads into a fine layer of dust during the approximately b months of dry weather. For a nus'bcr of years the road were sprinkled with water on cn almost continuous basis. However, with temperatures of 35 plus degrees and humidities cf 15 to 2C, the results were not adequate. During the past two years, io. 5 oil has been used ar.d has given good dust control. One to two applications have been sufficient. Seme Pentapriice has been successfully used with more permThaeneanct tureasl udlitgsg. ingThaendoilloasydsintegm isgivneos parodbelqeuma.te cThoentmroalt.erial Is relatively coarse and also is slightly damp or moist.: * The Transfer Point is in the same category as the shovel loading material is handled and there is no problem. The^uxi; i ary equipment such as patrols, dozers_tc. have much les'>od time than the Euclids so there is much less exposure and what control is adequate for the Euclids and drivers is more so for the auxiliary equipment operators. MJJLL: The dust problem In the mill is entirely concentrated in the Dry Mill. The rat 11 feed bins and the wet mill are no problem. The sources of dust in the dry mill are roll crushers, hammer ml!Is, screens, elevators and belt conveyors. There are 12 roll crushers, 6 hammer mills, 5^ screens, 17 elevators and 36 points of conveyor loading ar.d dischargi There arc U fans and their cyclones operating on dust collection systems The dryer exhaust fans are independent units. The ventilation fsr.s are exhausting cnproxirs.itoly RfiOO CFH. <*FM. lfj.COQ CFH and L'0,000 CFH respectively. Prior to January 20, 156b, an 13,000 CFi unit was operating on the system now connected to the hO.OOO CFH unit. 1 J. A. Kelley -2- December 30, 1964 All operating units or equipment in the Dry Kill are connected to ventilation systems. All belt discharges are hooded and concocted and ail chutes are covered. The installed duct systems are for the most part wel1-designed and balanced within the individual systems. However, in no instance has there actualiy been a surplus of fan capacity so that an increase of air flow throughout each individual system as a whole could be made. This situation has also been aggravated to a small degree by the various remodeling of the ore cir cuits curing the past. The activation of the 8,000 CFM fan system was the results of circuit revision. Another factor contributing to the inefficiency of the system has been the loss of air effectiveness by leaks in flexible connections, holes in eievator casings, open hand holes in chutes, etc. The following program for dust control in the Dry Kill is now under way and will have priority until all hazard is eliminated. 1. On January 20," 1364, the 18,000 CFM fan was replaced by a 4-0,000 CFM fan. The areas served by the connected system have shewn a very marked improvement end substan tiated that for the most part the system design is adequate if fan capacity is available. The cyclone for this system lias not been changed and some capacity is being lest. Also, the cyclone cannot settle the collected material at an excessive amount of dust and larger particles ere being discharged from the fan outlet which addos to the air pollution within the general shop and service area. % new cyclone arrangement has been designed and detailed. Installation has been scheduled to begin cn February 15* 1965, and completed by March 1, 1965. This will fully utilize the fan capacity and settle all materials within the ability of a cyclone. Estimated cost is $15,COO. 2. During tfie past year, a program or repair and maintenance cn all air ducts, chutes, casings, etc. has been in effect. Maintenance men have been directly assigned to this duty. This program is showing results not only in Letter use of existing air but also in the reduction of material spills and leaks each of which contribute to dust as well as sweeper chores. Still more emphasis is in effect cn this phase. All Cry Mill personnel have always been issuc'd approved respiraters and Instructed to wear them at ai1 tires. Compliance and enforcement cf this rule has r.ot been 1CC%, but is new being rigiciy enforced a tor supplies ore in stock and available at ;cuse. J. A. Kelley -3- December 30, 1964 4. Any dust in the nil! atmosphere will end does result in some build-up of dust on rafters, purlins, gutter boxes, sills, etc. This is true even with dust concentrations well below the allowable standards. If this dust is allowed to accumulate beyond a point, the vibrations of ,the mill cause the dust to shake back into the mill atmosphere and add to the concentration caused by the machines. The "sweepdown" of the mill buildings, etc. has not been done at adequate intervals and has added to the problem. A monthly ''sweepdown" interval is now in effect. 5. A dust count apparatus identical with that used by the State Board of Health is on hand. Supervisory personnel have been trained and checked out in the use of the equipment by the State Engineer. A complete schedule of dust concentration within the Dry Kill every month is now in effect. This will give a measure of progress and con trol after allowable concentrations are achieved. 6. The 18,000 CFM fan which was replaced by the 40,000 CFM fan is not now being used. It has been tentatively ear marked for replacing one of the smaller ventilation vans. The fan is presently in a very awkward location and mill space is at a premium. Although Engineering has made some primary layouts, no actual i ns ta 1iaticn has been scheduled. 7,. The dust concentrate readings have been taken on an Average sample. That is, an entire floor of the mill has been taken as an area from which a samples has been taken. Therefore;, some areas or a floor or fleers which have been considerably improved are stiil being contaminated from areas that are extremely difficult to correct and actual progress tends to be hidden by a rev; extreme -areas. One of these difficult areas is directly beneath the roll crusher installations.. The roll crushers which are the only actual concentrating machines in the Dry Kill (the banner mills are delaminating and size re duction machines on concentrates) are extremely difficult to hood and vent. The decision to replace them with a wet process will decrease the period of time of their con tributing to the dust problem. A wet process will also decrease the contributions of the hammer mills. The wet process program is. now underway. 8. There are no definite plans ver additional ce-dusting of concentrates in Ihe mill concentrate bins, At this time, there are several ideas v.Vitch require test ing but have not been definitely scheduled. J. A. Kelley -4- December 30, 1954 The skipping operation is not a dust-free operation, but is not a hazardous operation. If the cars ware loaded by hand, it wculd be. However, the remote control loading and operator house give adequate protection at this time. The operator is equipped with a respirator in case of the need to enter a dusty atmosphere. Ho change is contemplated at this time. HAUL I MG; * The dumping of the skip cars into the lower ore bins creates dust as does any handling of vermiculite concentrates. No personnel is involved in the dumping operation. The only exposure is whilechanging chutes curing which time no skipping is c'cr.e ar.d the area is naturally ventilated. Loading of the Kenworth truck beneath the lower ore bins is a dusty operation in a somewhat confined space. The drivers are respirator-equipped and after opening the loading gate do not need to remain at that point but can move a few feet to a clean location. The truck will not overflow, it takes approx imately 5 minutes to load the truck. Total leading time is about 1 hour per day. The ventilation problem is immense and other than a rigid enforcement of respirator wearing, no change is scheduled. The haul road to the river loading bins becomes very dusty during the dry season. Again water was formerly used but the situation has been adequately controlled by the use of oil as inthe case of the mine haul roads. The dumping of the Kenworth truck into either the river loading heppers or the horizontal storage creates dust in considerable quantities because the vermiculite has been handled through the skip system, lower ore bins and Kenworth truck loading. Each handling has been cumulative. However, actual dumping is in the open so exposure is reduced to a lew level. STORAGE; ^ The unloading of the horizontal storage bins requires the use of the Cat 955 loader-dozer. This is a dusty operation. The dust entrained into the atmos phere is kept to a minimum by careful operation of the machine. However, the operator is exposed and is respirator-equipped. The operator compliance with respirator wearing can be termed 1C0%. There is no practical answer other than careful use of a respirator. The ioad-out gates were equipped with hoods duct system and fan in 1955. The sHo-type storage bins (six 1250 ton) were built during the period March 1959"December 1961. Tire load-in elevator, the lead-out gates, belt discharge, load-out elevator and the discharge onto the river belt are equipped with a ventilation system and dust control is excellent, l/hen the silo-type storage bins (feur 1250 ton) for !Jo. 2 ore were built in 1953, the ventilation system was extended to include the discharge cates, belts, etc. A larger fan was installed capable of handling both systems. J. A. Kelley -5- December 30, 1964 Yne dust control at the storage silos and their respective load-out equip ment Is good and is adequate. Although there is no ventilation system on the screw and belt conveyor galleys across the top of the bins, there is no personnel exposure because bin changes etc. are made during downtime. LOAD!KG; Although the dust control of the actual loading of the river belt frcn the hoppers or storage bins is adequate, the result is dust containment rather than dust removal from the ere. In 1962 a system consisting of fan, cyclone and dust holding bin was in stalled at the discharge terminal cf the river belt. The ducts are con nected to the discharge hopper, sampler and loading chutes. The purpose of this installation was not only to contain the dust created by the loading into cars but also to actually remove the dust from the ore. Complete removal of dust'from the ore during car loading will give better products and eliminate the unloading problem at the plants-. The dedusting installation at trie loading terminal was only partly successful. The high loading rate ($0 to 100 TPi-l) and minimum headroom presents a very difficult aeration problem and much of the oust remains trapped within the ore stream. From 3C0 to 300 pounds of dust per can can be removed. Some extremely thin flakes of vermicuiite are always present in the removed dust. The vermiculite is excessive at the o00>7 rate so an average of about 300 to 400# per car is normal. There is additional air capacity available and two flexible exhaust ducts for use in both hopper cars and box cars have been tentatively designed. These wil1 be installed as soon as they are completely designed and the weather permits. There is some personnel exposure and respirators are furnished. It is not necessary to wear the respirator all the time--probably 5 minutes per horn--and compliance is very good. The downtown storage and loading facilities are comparable to the river storage and loading. All truck dumping is into open hoppers which reduces the hazard. Except for the truck leading, all leading is bagged. The bogging equipment is ventilated. EXPAND IHG PLAHT; The expanding plant including the special verxite equipment is no better or no worse than any normal commercial plant. Complete dust control will be designed into any new installation. LABORATORY; The regular mill testers do not wear respirators in the laboratory. They are respirator-equipped and are required to wear them when pickup concentrate samples in the cry mill, uigicl enforcement of this rule is in effect. J. f\. Kelley -6- Decemfcsr 30, 1964 The nine testers (testing bin checks, blest hole samples, prospect hole samples) v.'ear respirators v.hilo preparing dried samples by hammer milling, attrition milling and roll crushing. These rr.aohir.es are also ventilated. In addition to the dust concentration sampling outlined for the dry mill, a systematic monthly check will be made on other areas in order that the degree of exposure can be determined and control steps taken. RA51eich/jbg (/?, &