Manganese Recycling

Manganese Recycling

Manganese Recycling is essential to iron and steel production in the United States. Demand in metallurgical applications accounts for most of the manganese consumed in the United States, with ironmaking and steelmaking alone consuming 82 pct. The importance of manganese is related to the functions it performs. Manganese controls oxygen and sulfur impurities in steel, increases the strength, toughness, hardness, and hardenability of steel, and inhibits formation of embrittling grain boundary carbides. Normally, manganese metal is a brittle and unworkable substance; however, when alloyed in steels and other metals, it acts to produce tougher, harder, and stronger alloys. No economic substitute for manganese in iron and steel has been found. Thus, a continued secure supply of manganese is vital to any defense effort as well as to maintenance and growth of the U.S. economy.

The United States currently is dependent on foreign supplies of manganese, imported as ore, ferroalloy, or metal. The largest supplier of U.S. demand is the Republic of South Africa, followed by France, Australia, Gabon, Mexico, and Brazil (table 1). Most production of manganese is expected to continue to come from the Republic of South Africa, where the largest reserves by far are located.

World resources of manganese are ample for the foreseeable future, as are the resources of chromium, cobalt, and the platinum-group metals (PGM). However, past political and economic events have raised concern about the uninterrupted availability and reliability of supplies of these commodities. For this reason, these metals are considered strategic and critical materials. The risks of future disruptions of supply were considered high around the time of the 1978 Katangese rebellion in Zaire. The price of cobalt rose from $11/kg ($5/lb) in 1977 to $51/kg ($23/lb) in 1979. Even though some of this price increase was due to sharply increased demand, the rapid changes in the cobalt market generated significant concern about future disruptions to the supply of cobalt, and also chromium, manganese, and PGM. This concern led to studies on the strategic importance, availability, and supply vulnerability of a number of commodities, including manganese. Most of these studies either are now out of date or do not supply information on losses of the strategic and critical commodities due to waste disposal, downgrading, and/or export. The lack of knowledge on these unknown losses makes conservation efforts difficult.

Industry officials in the production, manufacturing, and recycling of strategic and critical commodities are reluctant to discuss the quantities of materials that go to disposal, downgrading, and export. This information is often considered to be proprietary in nature. Even when data are available, there is confusion between disposition of materials and recycling. For example, in a survey of seven scrap recyclers, the following estimates were obtained for disposition of scrap from the superalloy industry:

manganese-consumption-recycling

These estimates are typical of the data on processing, manufacturing, disposal, downgrading, and recycling of strategic and critical materials. Therein lies the difficulty in determining the amounts of critical and strategic commodities that are discarded, downgraded, or exported. This study was conducted to ascertain how the United States is using and losing its strategic and critical materials.

In 1980, the USBM reported the results of contract studies by Inco Research and Development Center, Suffern, NY, and Arthur D. Little, Inc., Cambridge, MA, to assess the domestic availability of chromium in scrap metal and the amount of scrap being recycled. These reports contain data up to 1976 and 1978, respectively; no updates of these studies were conducted following their publication. In 1976 and 1981, the National Materials Advisory Board (NMAB) conducted studies on the consumption of manganese, its strategic importance, and reserves and resources of the world.

In May 1985, the U.S. Congress, Office of Technology Assessment (OTA), produced a study entitled “Strategic Materials: Technologies To Reduce U.S. Import Vulnerability”. Included in the study was a set of recommendations to the USBM to conduct a survey of recycling-related activities. OTA recommended a scrap recycling study to update the chromium scrap metal information contained in two USBM publications, as well as to expand the scope of the previous studies to include information on scrap generated by the cobalt, manganese, and PGM industries, and to include the wastes generated by all the various industrial and Department of Defense (DOD) users of these four commodities.

Acting on this recommendation, in 1987 the USBM initiated a study of the four commodities. The main objective of this study was to produce a commodity-oriented structural model that would trace flow, recycling, and final disposition of the four identified commodities. The model then could be updated in subsequent years. A second objective of the study was to provide, in an understandable manner, an overview of the commodity flow. This overview would serve as a tool for the Congress and for industry associations to help in the study of that commodity’s vulnerability to political and availability factors outside the control of the United States. Another objective of the study was to highlight significant commodity loss areas where further research was required.

A hierarchical model was developed for the commodity cobalt. The model is generic and can be applied to other strategic and critical commodities. The model was applied to cobalt, chromium, and PGM. To meet the stated objectives of this study, the model also was applied to manganese, with slight modification.

Description of Flow Model

As stated in the introduction, the manganese flow model is based on the generic flow model developed for the commodities cobalt, chromium, and PGM, with some minor modifications. Development of the model was an iterative process; thus, the manganese model is the most comprehensive version of the commodity flow model.

The flow model shown here is a “snapshot” of a dynamically changing industry. This particular snapshot was taken in late 1992 using the data available at that time. Subsequent new information could, and in a few instances, does change the data displayed. However, only the data available at the time of the original writing are shown. Others could and should use the newest available data when updating this flow model.

Definitions

Apparent consumption.—Production plus net trade plus stock changes. (Note that neither reported nor apparent consumption is actual consumption. However, apparent consumption is very close to actual consumption.) A more detailed definition and calculation of apparent consumption is in the appendix.

Production.—Domestic mine production plus recycle.

Net trade.—Imports minus exports.

Stock change.—Beginning minus ending stocks.

Consumption—Apparent consumption, except where it is listed as reported consumption.

Reported consumption.—Those data reported to the USBM in response to the Bureau’s industry consumption survey questionnaires. In addition, estimated data from nonrespondents is often included in USBM reported consumption tables.

Home scrap.—Scrap generated during processing that is internally recycled within the generating company and that can be considered as being endlessly recirculated. It is some times referred to as “run-around scrap.” It is not counted as part of consumption.

Obsolete scrap.—Scrap generated by users and recyclers when used products are overhauled or when the product has reached the end of its productive life cycle.

Prompt scrap—Also called prompt industrial scrap or new scrap; consists of solids, turnings, grindings, sludges, and liquors generated during the manufacturing process when the primary product is fabricated into a finished product.

Run-around scrap.—Home scrap.

Losses.—Materials such as fume, spilled contaminated metal, scale, metal trapped in slag, material removed in pickling, plating wastes, grinding, etc.

Downgraded scrap—Scrap that is used for lower grade alloy, such as superalloy scrap used for stainless steel or alloy steel scrap used for cast iron.

Recovery—The practice of acquiring metals from obsolete material for recycle into new products.

Recovery loss.—Those obsolete materials that arc never collected for recycling. An example is obsolete material used as landfill.

Recycle—The process of collecting, cleaning, assaying, and sorting materials for reuse in industry.

Recycling loss.—Those losses that occur in the recycling process. For example: A major loss area is downgraded scrap material that gets recycled to lower quality metals, particularly where the metal in question is not required for the new alloy but is acceptable in the new alloy products.

Manganese ferroalloy and metal.—Ferromanganese plus silicomanganese plus manganese metal.

Manganese ferroalloy.—Ferromanganese plus silicomanganese.

Ferromanganese.—High-, medium-, plus low-carbon ferromanganese.

Ferroalloys.—All ferroalloys including ferrochromium, ferrochromium-silicon, ferromanganese, ferrosilicon, ferronickel, ferroboron, ferrovanadium, ferrotitanium, ferrotungsten, etc.

General Configuration

A typical manganese flow model is shown in figure 1. The appendix discusses the mathematical relationships in the model and gives the details of its application to the data for 1990. The percentage data come from calculated and estimated values shown in the appendix in table A-35. The supplies of new manganese come from imports of manganese ore, manganese ferroalloys, manganese chemicals, and metal, which are augmented by secondary production (scrap). In any given year, fractions of these materials go to exports, stocks, domestic processing, and manufacturing. Prompt scrap also augments the input of new manganese and scrap. During processing, about 14 pct of input reports as home scrap and is internally recycled. About 50 pct of input reports to processing losses, about 4 pct reports to downgraded material, and about 51 pct reports to manufacturing. Note that home scrap is not counted, as it is endlessly recycled, and counting it would be double counting. However, it is part of the recycling of the commodity. The processed material then goes to product manufacturing. During manufacturing, a small amount of manganese (about 5.5 pct) reports as losses and some reports as downgraded material (about 5 pct). The remainder goes to final products. Prompt scrap amounts to about 5.5 pct, of which 0.4 pct goes to export and the remainder to processing. After a normal use life, each product that is not in a dissipative end use becomes obsolete scrap and waste. The estimated amount recycled, based on literature data, was about 11.9 pct (81,800 st). Most of this recycled material is recycled for its iron content, but not for its manganese content.

manganese-consumption typical flow model

Properties of Flow Model

The flow model described in IC 9252 and IC 9303 is generic in nature and, thus, can be used for a wide variety of commodities with only minor modifications. The model is easily updated and generally understood by the public, and it highlights areas where recycling research is needed. The model is hierarchical, with three levels: the entire manganese industry, the individual industry level, and the individual plant level. The data in this report cover the entire manganese industry and the individual industry level.

Assumptions in Model

In the development of the model, a number of assumptions had to be made. These are as follows:

  1. Where data were found, the percentages reporting in each category were used. Where no current data were available, data from NMAB 406 were used and assumed to be still applicable.
  2. The use lives of various products vary over a wide range, NMAB estimated the life spans of a number of products. Its estimation for the life spans of superalloys, stainless and heat-resistant (SHR) steels, full alloy steels, high-strength low-alloy (HSLA) steels, tool steels, and unspecified steels was 5 years. For other alloys (based on aluminum food-handling products and manganese bronze ship parts), life span was estimated to be 10 years. The life spans of carbon steels and cast irons are based on the current life cycles of automobiles and light trucks because of those industries high consumption of these materials. Currently, the life cycle of a motor vehicle is estimated to be about 10 years. The life span of miscellaneous and unspecified materials is assumed to be 5 years, based on the most frequent life spans of metal products. Chemical and battery products are nearly all used in dissipative end uses and are not recycled.
  3. Thus, it is assumed that obsolete scrap available for recycle in 1990 would come from 1980 consumption of carbon steels, cast irons, and other alloys, and from 1985 consumption of superalloys, SHR steels, full alloy steels, HSLA steels, tool steels, unspecified steels, and miscellaneous and unspecified metal products.
  4. Unless otherwise stated, all manganese quantities are short tons of contained manganese. All values reported are the best estimates possible with currently available data.

Manganese Industry

Most manganese is consumed by the iron and steel industries in the United States. The metallurgical industry consumes about 88 pct; the chemical and battery industries, about 12 pct. The major overall end use is for carbon steels, which account for about 70 pct of metallurgical consumption or about 61 pct of total apparent consumption of manganese.

In 1990, the United States imported 100 pet of any new manganese consumed. There has been a trend in manganese-producing countries to vertically integrate their manganese industry by developing their own manganese ferroalloy production facilities. This has led to a significant change in the percentages of manganese imported as manganese ore versus manganese imported as ferroalloys. Ore imports have fallen from 79 pct of imports in 1969 to 25 pct in 1990, whereas manganese ferroalloy imports have risen from 21 pct in 1969 to 75 pct in 1990. This trend of producer nations toward their own production of manganese ferroalloys and metal has contributed to a decline in U.S. ferroalloy production.

The breakdown of manganese consumption in U.S. industries in 1990 is shown in tables 2 and 3, and an overview of the U.S. manganese industry is shown in figure 2.

In 1990, the input to manganese-consuming industries included domestic production of 1,000 st of contained manganese, manganese ore containing 169,000 st of manganese, ferroalloys and metal containing 505,000 st of manganese, shipment of stockpile excesses of 22,000 st of manganese, and industry stocks containing 324,000 st of manganese. Total input equals 1,021,000 st of contained manganese. Of this amount, 60,000 st was exported as ore, manganese ferroalloys, and metal. Another 266,000 st of contained manganese reported back to industry stocks, leaving 58,000 st for consumption from industry stocks. Materials containing 634,214 st of manganese went directly to the manganese-consuming industries, and ore containing 60,786 st of manganese was sent to U.S. ferroalloy producers. During manganese ferroalloy processing, 6,786 st of manganese contained in slag and particulates reported as losses, while 54,000 st of manganese reported to manganese-consuming industries as ferroalloy.

The metallurgical industries consumed materials containing 602,212 st of manganese. The manganese chemical industries consumed material (mostly ore) containing 40,000 st of manganese, and the battery industry consumed ore containing 46,000 st of manganese.

manganese-consumption supply demand relationships

The only significant current domestic supply of manganese is recycled scrap. However, processing iron and steel scrap for recovery of manganese is insignificant. Steels are recycled primarily for their iron content. A furnace charge for steels may consist of as much as 53 pct prompt and purchased steel scrap, while cast iron furnace charges may contain 94 pct scrap. Other alloys containing manganese maybe recycled, but not specifically for their manganese content. (An example is aluminum beverage cans, which are recycled for their aluminum content.) Manganese chemicals and batteries generally are consumed in dissipative end uses and, thus, are not recycled.

Carbon Steels

Carbon steels are consumed in the manufacture of automobiles, appliances, structural steels, and a wide variety of other products. During 1990, the carbon steel industry consumed 422,085 st of manganese, mostly in the form of manganese ferroalloys. The flow model for manganese in carbon steels is shown in figure 3. An additional 17,398 st of manganese in prompt scrap and 56,880 st of manganese in home scrap also were consumed during processing. Material containing 247,996 st of manganese reported to processing losses (slags, dusts, etc.). Other materials containing 21,222 st of manganese were downgraded to lesser materials. The remaining material, containing 170,265 st of manganese, reported to product manufacturing.

During manufacturing, material containing 17,398 st of manganese was recycled to processing as prompt scrap, material containing 26,617 st of manganese was downgraded to lesser metals, and material containing 26,617 st of manganese reported to manufacturing losses (dusts, contaminated metal, grindings, etc.). Carbon steel final products contained 99,633 st of manganese.

Because carbon steel products are heavily used in automobiles and appliances and these products are estimated to have a 10-year life cycle, it is assumed that carbon steels have a 10-year life cycle. Material containing 687,434 st of manganese from 1980 carbon steel industry consumption was potentially available for recycling. While considerable amounts of this material were recycled to various steel melts as part of the scrap charges to the furnaces, essentially none was recycled specifically for its manganese content. During 1980 production, 525,124 st of manganese reported to losses and downgraded material. Material containing 162,310 st of manganese was available for recovery. Unknown and unrecovered losses amounted to 113,508 st of contained manganese. Feed to recycling contained 48,802 st of manganese. During recycling, material containing 4,880 st of manganese was lost. Scrap containing 43,922 st of manganese was recycled in 1990.

manganese-consumption overview

manganese-consumption carbon steels flow model

Stainless And Heat-Resistant Steels

SHR steels are used in many environments where resistance to corrosion or heat is required. They are also employed in end uses as varied as kitchen sinks or other sinks, counter tops, etc.; decorative components of automobiles and marine vessels; and jet engine parts. The flow model for SHR steels is shown in figure 4. The total feed to SHR steels includes obsolete scrap containing 2,400 st of manganese, prompt scrap containing 950 st of manganese, home scrap containing 3,107 st of manganese, and new material containing 20,659 st of manganese. During processing, in addition to home scrap, material containing 13,548 st of manganese reported to processing losses, while material containing 1,159 st of manganese reported to downgraded scrap, and material containing 9,302 st of manganese went as feed to manufacturing.

During manufacturing, material containing 1,447 st of manganese reported to downgraded scrap, material containing 145 st of manganese reported to manufacturing losses, and material containing 950 st of manganese returned to processing as prompt scrap. The final products contained 6,760 st of manganese.

Obsolete scrap for 1990 consumption of manganese in SHR steels came from 1985 production of these materials. From 1985 apparent consumption of manganese in SHR steels, material containing 18,694 st of manganese potentially would be available for recycle. Available data indicate that SHR steels containing 1,773 st of manganese were exported in 1990. Production losses contained 13,213 st of manganese. This left scrap containing 3,708 st of manganese available for recovery, Of this amount, scrap containing 1,041 st of manganese was lost to unknown and unrecovered losses. The remaining scrap, containing 2,667 st of manganese, was processed for recycling. During recycling, material containing 267 st of manganese reported to recycling losses, and scrap containing 2,400 st of manganese reported to 1.990 SHR steel consumption.

Full Alloy Steels

Full alloy steels are employed in many end uses where the special alloying constituents provide the necessary strength for the intended applications. These alloys are most frequently used as structural steels in applications such as bridges and buildings. The flow model for full

manganese-consumption stainless and heat-resistant steels flow model

alloy steels is shown in figure 5. New manganese material feed to processing contained 55,538 st of manganese. Obsolete scrap containing 6,450 st of manganese was also consumed. Additional feed to processing was home scrap containing 8,354 st of manganese and prompt scrap containing 2,555 st of manganese. During processing, loss material containing 36,421 st of manganese and downgraded material containing 3,117 st of manganese were generated. Processing material feed to manufacturing contained 25,005 st of manganese.

During manufacturing, in addition to prompt scrap, loss materials containing 3,907 st of manganese and downgraded material containing 3,907 st of manganese were produced. Final products contained 14,635 st of manganese.

Potentially available material for recycling was provided by 1985 apparent consumption of manganese for full alloy steels. This material contained 51,200 st of manganese. Production losses contained 39,111 st of manganese, leaving material containing 12,089 st of manganese for recovery. Unknown and unrecovered material containing 4,922 st of manganese was lost. Recovered material containing 7,167 st of manganese reported to recycling. Recycling loss material contained 717 st of manganese, while scrap containing 6,450 st of manganese was recycled.

High-Strength Low-Alloy Steels

These alloys originally were developed for the Alaska Pipeline, where environmental conditions required unusually high strength materials. These steels are now used extensively as structural steels in automobiles, buildings, and bridges, as well as having some uses where the properties of these steels protect against atmospheric corrosion. The flow model for HSLA steels is shown in figure 6. Feed to processing included new material containing 35,053 st of manganese, obsolete scrap containing 4,071 st of manganese, prompt scrap containing 1,613 st of manganese, and home scrap containing 5,272 st of manganese. During processing, loss material containing 22,987 st of manganese and downgraded material containing 1,967 st of manganese were generated. The remaining material, containing 15,782 st of manganese, went as feed to manufacturing.

During manufacturing, prompt scrap containing 1,613 st of manganese, loss material containing 2,466 st of manganese, and downgraded material containing 2,466 st of manganese were produced. Final products contained 9,238 st of manganese.

manganese-consumption high-strength low-alloys steels

From 1985 apparent consumption of manganese in HSLA steels, material containing 43,291 st of manganese was potentially available for recycling. Production losses contained 33,069 st of manganese. Unknown and unrecovered loss material contained 5,699 st of manganese. During recycling, material containing 452 st of manganese was lost. The remaining material was recycled obsolete scrap that contained 4,071 st of manganese. Total losses in HSLA steels in 1990 were estimated to contain 36,037 st of manganese.

Tool Steels

Tool steels are designed for cutting, forming, or otherwise shaping a material The flow model for tool steels is shown in figure 7. New material containing 299 st of manganese, obsolete scrap containing 35 st of manganese, prompt scrap containing 14 st of manganese, and home scrap containing 45 st of manganese were the feed to processing. Loss material containing 196 st of manganese and downgraded scrap containing 17 st of manganese were produced during processing. Processed material containing 135 st of manganese was sent as feed to manufacturing.

During manufacturing, prompt scrap containing 14 st of manganese, downgraded scrap containing 21 st of manganese, and loss material containing 21 st of manganese were produced. The final products contained 79 st of manganese.

Material containing 440 st of manganese from 1985 apparent consumption of manganese in tool steels was potentially available for recovery and recycling. Production losses in 1985 contained 336 st of manganese. Unknown and unrecovered loss material contained 65 st of manganese. Of the material sent to recycling (39 st of contained manganese), recycling losses contained 4 st of manganese. Obsolete scrap recycled in 1990 for tool steels contained 35 st of manganese.

Unspecified Steels

This category includes, as a minor component, steels for which the surveyed companies did not specify the type(s) of steel, and steel categories for which the data had to be combined to avoid revealing company proprietary data, including high-, medium-, and low-carbon ferromanganese in electric steels; medium- and low-carbon ferromanganese in SHR steels; silicomanganese in electric and tool steels;

manganese-consumption tool steels

and manganese metal in carbon steels, HSLA steels, and electric steels. For these steels, the “all steels” flow model shown in figure 8 was used.

Material feed to processing included 3,061 st of contained manganese in new manganese, 356 st of manganese in obsolete steel scrap, 141 st of manganese in prompt scrap, and 460 st of manganese in home scrap. During processing, loss material containing 2,008 st of manganese and downgraded scrap containing 172 st of manganese were generated. Processed steel containing 1,378 st of manganese was sent to manufacturing.

During manufacturing, downgraded scrap containing 215 st of manganese and loss material containing 215 st of manganese were generated. The final products contained 807 st of manganese.

Material consumed in 1985 was potentially available for recycling and contained 1,442 st of manganese. During production in 1985, losses amounted to 1,102 st of contained manganese. Unknown and unrecovered losses were small and were added to recycling losses. Recycling loss material contained 34 st of manganese. Obsolete scrap containing 306 st of manganese was recycled. The amount of recycled obsolete scrap from 1985 production of unspecified steels was less than the amount of material estimated to be recycled in this end use. Thus, obsolete scrap from other end uses (possibly downgraded scrap) containing 50 st of manganese also was recycled to this end use in 1990.

Cast Irons

Cast irons are used in a variety of applications. Some of the major end uses are as engine blocks, some types of gears, and large pieces of many different types of machinery. The flow model for cast irons is shown in figure 9, New feed material containing 2,559 st of manganese went to processing. Obsolete scrap containing 13,467 st of manganese, prompt scrap containing 8,978 st of manganese, and home scrap containing 17,645 st of manganese were also part of the feed to processing. During processing, material containing 10,662 st of manganese reported to processing losses. Material containing 14,341 st of manganese was feed to manufacturing.

During manufacturing, material containing 224 st of manganese reported as manufacturing losses, and prompt scrap containing 8,978 st of manganese was produced and recycled back to processing. Final products contained 5,139 st of manganese.

manganese-consumption unspecified steels flow model

Typically, today’s automobiles last an average of 10 years. Because automobile engine parts are the heaviest users of cast irons, a life span of 10 years is assumed. Thus, potentially available obsolete scrap for 1990 production would come from 1980 apparent consumption of manganese in cast irons. Thus, obsolete scrap containing 26,492 st of manganese potentially would be available for consumption in 1990. This material is not recycled for its manganese content, but for its iron content. Production losses in 1980 contained 17,995 st of manganese. The remaining products would then become obsolete scrap in 1990. Scrap containing 8,497 st of manganese was available for recovery in 1990. The major loss of material would be in a recycling loss of 10 pct, or 850 st of manganese. This would leave recyclable material containing 7,647 st of manganese. An additional portion of manganese-bearing scrap containing 5,820 st of manganese from other end uses (possibly as downgraded steel scrap) is added to give 13,467 st of manganese in recycled obsolete scrap.

Superalloys

Superalloys are metals that have very high strengths and that are resistant to corrosion and high temperatures.

Because of their high values (up to $31/kg or $14/lb), much emphasis is placed on recycling these materials. Typical uses are in jet aircraft engine components, both moving and stationary parts. A number of these alloys are also used for applications in highly corrosive environments. Typically, superalloys are nickel- and cobalt-based alloys, but there are also some iron-based superalloys. The flow model for manganese in superalloys is shown in figure 10. Processing feed materials included new material containing 198 st of manganese, 41 st of manganese in obsolete scrap, 81 st of manganese in prompt scrap, and 224 st of manganese in home scrap. During processing, material containing 4 st of manganese reported as processing losses, and material containing 7 st of manganese reported to downgraded scrap. Processed metal feed to manufacturing contained 308 st of manganese.

During manufacturing, material containing 26 st of manganese reported to manufacturing losses, and scrap containing 33 st of manganese reported to downgraded scrap. Prompt scrap containing 111 st of manganese also was produced. Part of this prompt scrap, containing 30 st of manganese, was exported. The remaining prompt scrap, containing 81 st of manganese, was recycled to processing. Final products contained 139 st of manganese.

manganese-consumption cast irons flow model

Material from 1985 apparent consumption of manganese in superalloys contained 414 st of manganese and is potentially available for recycling. Production losses in 1985 claimed 173 st of contained manganese. During recovery, scrap containing 195 st of manganese reported to unknown and unrecovered losses. Of the obsolete scrap going on to processing, material containing 5 st of manganese reported to recycling losses, and scrap containing 41 st of manganese was recycled. Thus, scrap and waste containing about 373 st of manganese, as well as chromium, cobalt, and nickel, are lost to efficient recycle. This would amount to about 1½ times the 1990 apparent consumption of manganese in superalloys.

Data shown by Papp give an estimated breakdown of the various scrap and loss components in the flow model for superalloys for 1990 (table 4). Note that the prompt scrap that was exported contained mostly grindings and turnings (69 pct), which frequently are not suitable for recycle back to vacuum-melted superalloys because of possible contamination. All 30 st of manganese in the exported prompt scrap is lost to domestic production of superalloys, which contain chromium, cobalt, and manganese—strategic and critical materials. Total losses of superalloys to wastes, downgraded scrap, and export (405 st contained manganese) amounted to about double the 1990 apparent consumption of manganese in superalloys.

Other Alloys

Materials in this industry are aluminum alloys, copper alloys, nickel alloys, and various other alloys, in the majority of which manganese is present as a minor component. These materials are used in a wide variety of
applications: aluminum alloys for beverage containers and marine, automobile, and aircraft parts; copper alloys for switches, circuit breakers, continuous casting molds, heat exchanger tubes and pipe; nickel alloy for seawater corrosion resistance; and miscellaneous other products, depending on the alloy in question.

The flow model for other alloys is shown in Figure 11. Processing feed consisted of new materials containing 17,638 st of manganese, prompt scrap containing 4,380 st of manganese, home scrap containing 5,328 st of manganese, and obsolete scrap containing 8,648 st of manganese. During processing, material containing 4,501 st of manganese reported to processing losses, and the remaining materials, containing 26,171 st of manganese, reported as feed for manufacturing.

manganese-consumption superalloys flow model

manganese-consumption superalloy scrap

During manufacturing, prompt scrap containing 4,380 st of manganese and manufacturing loss material containing 410 st of manganese were produced. The remaining material was in final products containing 21,381 st of manganese.

These products are assumed to have a 10-year use life. Thus, the 1980 apparent consumption of manganese in other alloys was potentially available for recycling and contained 26,286 st of manganese. However, this material is not known to be recycled solely for its manganese content, but is recycled rather for its base metal content.

During production, material containing 4,911 st of manganese was lost. Unknown and unrecovered losses accounted for an additional 11,766 st of contained manganese. During recycling, additional material containing 961 st of manganese was lost, leaving recycled obsolete scrap containing 8,648 st of manganese for new production.

Miscellaneous and Unspecified Materials

This category encompasses small metallurgical end uses of manganese, including the consumption of an unknown quantity of material, in which high-carbon ferromanganese is used to produce superalloys, and medium- and low- carbon ferromanganese and silicomanganese are used to produce other alloys. (The amount of these materials in those end uses is withheld to avoid disclosing company proprietary data.) The flow model for this category of material is a metallurgical model because most of the materials in this group are metals (figure 12). Processing feed included new material containing 7,245 st of manganese, obsolete scrap containing 2,409 st of manganese, prompt scrap containing 1,612 st of manganese, and home scrap containing 1,959 st of manganese. During processing, material containing 1,659 st of manganese reported to processing losses, and material containing 474 st of manganese reported to downgraded scrap. Processing material feed to manufacturing contained 9,133 st of manganese.

During manufacturing, material containing 1,612 st of manganese reported as prompt scrap, material containing 1,438 st of manganese reported to downgraded scrap, and material containing 142 st of manganese reported to manufacturing losses. The final products contained 5,941 st of manganese.

Material from 1985 apparent consumption of manganese in miscellaneous and unspecified materials potentially available for recycle contained 12,210 st of manganese. Production loss material contained 4,696 st of manganese. Unknown and unrecovered losses accounted for 4,837 st of contained manganese, and recycling losses accounted for an additional 268 st of contained manganese. Obsolete scrap recycled contained 2,409 st of manganese.

Chemicals

Manganese chemicals are used for oxidation, water treatment, and a number of other purposes. The flow model for manganese chemicals is shown in figure 13. Chemical processing consumed new material containing 40,000 st of manganese in 1990. During processing, material containing 1,200 st of manganese reported to

manganese-consumption other alloys flow model

manganese-consumption chemicals flow model

processing losses. The remaining material reported to chemical manufacturing and contained 38,800 st of manganese. During manufacturing of manganese chemicals, material containing 1,940 st of manganese reported to manufacturing losses. The final chemical products contained 36,860 st of manganese.

Manganese chemicals, like most chemicals, are employed in dissipative end uses. Thus, the manganese content is not readily available for recycle.

Batteries

Manganese has long been used in zinc-carbon dry cell batteries. New manganese, ultimately in the form of manganese dioxide containing 46,000 st of manganese, was consumed by the battery industry in 1990. The flow model for manganese in batteries is shown in figure 14. During processing of the material, 1,380 st of contained manganese reported as processing losses. Processed material containing 44,620 st of manganese went as feed to manufacturing. During manufacturing, material containing 2,231 st of manganese reported as manufacturing losses, and material containing 42,389 st of manganese reported in the final products. No economical method for recycling the manganese in batteries has been found to date.

Overall Manganese Industry

This is a composite flow model summed from the values in all manganese industry flow models described above. The flow model is shown in figure 15. Processing feed consists of new manganese material containing 606,413 st of manganese, recycled obsolete scrap containing 81,799 st of manganese, prompt scrap containing 37,722 st of manganese, and home scrap containing 99,274 st of manganese. Material reporting to processing losses contained 342,562 st of manganese, and material reporting to processing downgraded scrap contained 28,135 st of manganese. The remaining material, containing 355,240 st of manganese, reported as processing feed to manufacturing.

During manufacturing, prompt scrap containing 37,752 st of manganese was produced. Superalloy prompt scrap containing 30 st of manganese was exported, and the remaining prompt scrap, containing 37,722 st of manganese, went to processing. In addition, manufacturing downgraded scrap containing 36,144 st of manganese and manufacturing loss material containing 38,344 st of manganese were produced. Final products contained 243,001 st of manganese.

Potentially available obsolete materials for recovery and recycle contained 953,903 st of manganese, an amount equal to about 1.4 times the 1990 apparent consumption of manganese. Of this potentially available material, material containing 1,773 st of manganese was exported. Production losses accounted for 646,481 st of manganese. Unknown and unrecovered losses contained 221,282 st of manganese, and recycling losses contained 8,438 st of manganese. Recycled obsolete scrap contained 81,799 st of manganese. This is about 8 pct of the material potentially available for recycle and accounts for 12 pct of 1990 apparent consumption. The low level of recycled manganese was because of the unfavorable economics of recovering manganese from steel slags, the principal destination of steelmaking process losses.

manganese-consumption batteries flow model

Summary

A commodity flow model was developed for the industries that consume manganese. Based on available data, the model follows manganese through its processing, manufacturing, and recycling operations, showing estimated values for material lost through these operations. The model was developed using certain estimates and assumptions and the best data available at the time. The model can be updated easily as new data become available. The multiplication factors will all change with time. New factors can replace older ones as data are acquired.

An industry flowchart was presented for each of the industries that consume manganese. The overall flow of the manganese commodity was also presented. The apparent consumption of manganese in 1990 was 695,000 st, which includes ferroalloy production losses. The estimated amounts of contained manganese consumed by the various industries are shown in table 2: the metallurgical industries- 609,000 st (about 88 pct of 1990 apparent consumption), the chemical industry—40,000 st (about 6 pct), and the battery industry-46,000 st (about 7 pct). Of the metallurgical industries consumption, approximately 69 pct went to carbon steels (about 61 pct of the total 1990 apparent consumption). The next three highest consumers of manganese were the full alloy steels industry—61,988 st (9 pct of total 1990 apparent consumption), the battery industry, and the chemical industry. All other metallurgical industries combined equaled 18 pct.

Based on the estimated life spans of the various products and the estimated amounts consumed in 1980 (10 years), 1985 (5 years), and 1990 (same year), there were potentially recyclable products containing 953,903 st of manganese (figure 15). Recycled obsolete scrap contained 81,799 st of manganese, or 12 pct of the 1990 apparent consumption of manganese. There currently is no means of accurately tracing how much manganese-bearing steel scrap is actually recycled to the same end use or another manganese-consuming end use.

The 10 highest loss areas for manganese in 1990 accounted for 88 pct of the total losses during processing, manufacturing, and recycling (table 5). The industry with the biggest loss was the carbon steel industry. Carbon steel processing losses, processing-downgraded scrap, manufacturing losses, manufacturing-downgraded scrap, unknown and unrecovered losses in recovery, and recycling losses amounted to an estimated 435,960 st of contained manganese and accounted for 72 pct of total manganese losses in 1990. Most other losses of 2 pct and more were in the iron and steel industries.

manganese-consumption loss materials

Conclusions

A manganese flow model has been developed, The mathematical relationships in the model are discussed in the appendix. The model estimates the distribution of 695,000 st of manganese consumed in the 12 manganese- consuming industries. Initially, 6,786 st of manganese was lost in domestic ferromanganese and metal production. The best available data estimate that about 445,185 st of manganese was lost during processing and manufacturing operations: 380,906 st to waste and 64,279 st to downgraded scrap. The 37,722 st of manganese in prompt scrap that was produced during manufacturing and the 99,274 st of manganese in home scrap that was generated during processing were efficiently recycled. Of the obsolete material potentially available for recycling, estimated with current available data, only the disposition of about 81,799 st of manganese to recycling can be followed. Obsolete materials containing 646,481 st of manganese reported to production losses. Obsolete material, mostly SHR steel scrap and superalloy scrap, containing 1,773 st of manganese was known to be exported. The remaining obsolete material, containing 221,282 st of manganese as unknown, unrecovered, use-life, or dissipative losses, cannot be traced with current data. There is a need to obtain data that trace where this material goes. Thus, it is recommended that the USBM make changes in its data-gathering survey sheets to obtain the missing information on a continuing basis. This would provide a continuously up-to-date flow model that can be supplied to those requiring the information in developing national policy regarding strategic and critical materials.