P. R. Morey

Botanically what is raw cotton dust

The objective of this study was to determine the specific botanical ingredients present in respirable raw cotton dust. Significant differences in content of gross leaflike (bractcontaining) trash were found between several grade divisions of raw cottons. For example, higher grades of raw cotton (strict low middling = SLM) contained less leaflike trash than lower grade cottons (low middling = LM). The potential for production of fine particulate from botanical trash materials plus lint and linters was determined in the laboratory by an abrasive milling test. Bract and wood fragments were the most friable of all plant materials found in raw cottons whereas seed meat, lint, linters and seed coat were the least friable. Respirable (10 less than 10 micrometers) raw cotton dusts associated with the processing of middling, SLM and LM raw cottons were predicted to contain the following % weight composition of specific vegetable ingredients: leaflike = 70--72%, stem = 13--18%, bark = 3--8%, exocarp-mesocarp = 3.6%, endocarp = 1--2% and seed = 0.5--2%. Bract is the most abundant component in respirable raw cotton dust.

Variation in trash composition in raw cottons

Raw cotton from 4 machine picked varieties and 2 machine stripped varieties is examined by stereomicroscope and bright-field microscopy for presence of plant trash(bract, leaf, stem, seed, boll, and weed fragments-size range 841-2000mum) that gives rise to cotton dust during yarn manufacturing operations. Bract was found to be the major trash component in all raw cottons examined. Cotton leaf and non-cotton weed materials were also major trash components in most raw cottons.

Botanical trash present in cotton before and after saw-type lint cleaning

The % by weight content of leaf-like, stem, boll, seed, and weed materials sifted (3360 mum greater than particle size greater than or equal to 595 mum) from visible wastes of the Shirley Analyzer was determined for a lint sample taken after ginning but before cleaning and for a second lint sample taken after one stage of saw-type cleaning. The % by weight content for bract and leaf increased with decreasing trash particle size. The content of cotton seed coat fragments decreased with reduction in trash particle size. Approximately 1/4 of the botanical wastes consisted of weed materials, including grass particles. Lint cleaning was ineffective in reducing the % by weight content of leaf-like trash. Some selective removal of stem trash occurred as a function of lint cleaning.

Gram-Negative Bacterial Content and Fiber Properties of Raw Cotton:

The content of gram-negative bacteria was determined for 109 samples of the 1978 crop of American upland raw cotton derived from seven grade divisions and five visual color groups. The populations of gram-negative bacteria entrained in these raw cottons varied from 1.5 X 1010 to 1.5 X 1014 for standard bale size (217.7 kg) lots. Raw cotton fiber parameters, including upper-half-mean length, length uniformity, strength, micronaire, maturity, and fineness, were all significantly and inversely correlated with the content of entrained gram-negative bacteria. The yellowness of raw cottons as measured by the cotton colorimeter was significantly and positively correlated with bacterial content. About half of the variability of gram-negative bacterial content in raw cotton samples of the 1978 American upland crop can be accounted for by variation in micronaire (r2 = 0.504).

Endotoxin Content and Fiber Properties of Raw Cotton

The content of endotoxin was determined for 255 samples of 1979 crop, American upland raw cotton derived from seven grade divisions and five color groups. A bale of raw cotton from the better white grades contained less than one gram ofendotoxin, whereas tinged and yellow stained cottons were found to have five or more grams of this microbial material. Fiber yellowness was significantly and positively correlated with endotoxin content of representative raw cottons from the Southwest. By con trast, the endotoxin content of representative cottons from all other major geo graphical regions was significantly and inversely correlated with fiber maturity. For the 1979 crop there was an absence of significant differences in endotoxin levels among representative sample groups from five major U.S.A. growing regions.

Botanical trash analysis of raw materials used in the cotton garnetting industry

The botanical nature of the trash in raw materials and batting from 5 cotton garnetting plants was compared with that present in raw cottons utilized by cotton yarn manufacturers. Linters processed by garnetters contained less (0.11%) leaflike (cotton bract, cotton leaf, and weed leaf) trash than that found in raw cottons (0.45–1.79%). The amount of leaflike trash present in soft cotton mill wastes used by garnetters was equal to or greater than that found in raw cottons. Milling tests showed that leaflike fragments removed from raw cottons were more friable than similar botanical material removed from garnetting raw materials including gin motes and soft cotton mill wastes. The amount of seed trash (mostly seed coat fragments) in linters, soft cotton mill wastes, and gin motes was greater than in raw cotton. The low prevalence of byssinosis that has been reported for nontextile cotton industries such as garnetting and waste recycling (willowing mills) might be explained, in part, (A) by the low content o...

Plant trash in linters and willowed picker: materials used in the cotton garnetting industry

First cut linters and willowed picker, used in cotton garnetting, were examined for content of cotton bract an other plant trash. Bract was found to be a minimal contaminant of the trash of first cut linters. A significant amount of bract (about 9% of the trash) was present in willowed picker. Cotton seed hulls, a valuable oil mill by product, contained an insignificant amount of bract trash.

Bract and leaf in the process stream in cottonseed oil mills

The objective of this study was to determine the amount of bract, leaf and other trash materials present in the process stream in cottonseed oil mills. The combined percent by weight of bract and leaf present in seed received from gins, seed exiting the cleaners, seed exiting the second-cut delin-ters and seed hulls from the huller/separators was 0.114, 0.033, 0.003 and 0.0%, respectively. The amount of bract and leaf in cottonseed received by the oil mill is about one order of magnitude less than that found in raw cotton utilized by the textile industry. In cottonseed oil mills large amounts of seed fragments are generated de novo and added to the process stream during saw delintering. Low levels of bract and leaf in the cottonseed process stream may account for the reported low prevalence of byssinosis found in the industry.

Use of a fluorescent tracer technique to study the botanical trash composition of cotton dust

Fluorescently dyed leaf trash of known particle size distribution (XN=66 µm) was prepared and blended into raw cotton which was subsequently processed in a model cardroom. The XN of the added leaf tracer collected in undercard and Pneumafil filter wastes was reduced to 64 and 54 µm, respectively. The XN of vertically elutriated leaf tracer was somewhat less (3.8 µm) than the XN (4.4 µm) of a small number of potentially respirable particles present in the raw leaf tracer. The fluorescent tracer technique, as applied to carding, offers a direct means of comparing the friability of the different botanical trash components found in raw cotton.

Evaluation of a fluorescent dust tracer technique in cotton ginning

A technique employing a fluorescent tracer for following the break-up and dispersion of cotton trash has been developed. Senescent cotton leaves were treated with a fluorescent dye, pulverized to match the same particle size distribution as naturally occurring leaf in raw seed cotton and uniformly incorporated into the seed cotton mass prior to processing in a saw-type micro-gin. A control lot was similarly processed, excluding any dye. Airborne samples collected from the major fugitive dust emission points by standard techniques, macro trash samples collected from four locations, and the final condensed lint product clearly show that the use of such tracers is not only feasible but highly useful in determining the locations where respirable dust is emitted. From the fraction of labelled tracer material found at any site, the relative amounts of both total and respirable dust emissions of that plant component can be estimated from the known masses of dyed material added to a given mass of seed cotton. Estimates of the relative severity of fugitive dust emissions from various processing steps in a cotton gin are presented based on vertical elutriator, high volume and multistage cascade impactor sampler data.