Tons Of Iron Ore Research Articles

Geology and geochemistry of the high-grade Zankan magnetite ore, Western Kunlun Mountains, NW China

Over the past decade, several magnetite-rich iron deposits have been discovered in the Taxkorgan region of the western Kunlun Mountains of northwestern China. These include the Zankan, Jiertieke, Laobing, Yelike, and Taaxi iron deposits. Prospective iron ore reserves are estimated at over 1 billion tons, with an average magnetite grade of 28% (Feng et al., 2018). The largest of the deposits, the Zankan Iron Deposit (ZID), is estimated to contain 628 million tons of iron ore, with at least 10% of the ores being high-grade (TFe > 50 wt%). However, the geological processes by which the high-grade ores in the ZID were formed remains poorly constrained. In this study, we combine whole rock and ore geochemistry data, oxygen and sulfur stable isotopes, and uranium-lead and hafnium isotopes from zircons to elucidate the plausible mechanisms underpinning the formation of the ZID ores. Based on mineralogy, we define two ore types. Type 1 is essentially comprised of quartz and magnetite, interlayered with schist, and it retains the sedimentary fabrics of the precursor iron-rich sediments which were an iron formation (IF). Type 2 formed by the intrusion of a dacite-porphyry into the IF which led to magnetite remobilization and recrystallization as manifest in magnetite-ferro actinolite veining. Rare earth element (REE) characteristics of the high-grade ores differs from those of the precursor IF, with chondrite normalized REE patterns showing enrichment of LREE and significant negative europium anomalies close to those of the dacite-porphyry. The oxygen and sulfur isotopic composition of magnetite and pyrite in the high-grade ores suggests a further meteoric influence on the ZID with silica enrichment driven by leaching of the precursor IF from elsewhere in the sequence. Circulation of the ore forming fluid is attributable to the development of faults and fracture zones that resulted from the intrusion of the dacite-porphyry. Laser ablation uranium-lead analyses of zircons from the dacite-porphyry yield two groups with ages of 551.25 ± 3.32 Ma and 497.82 ± 3.81 Ma, representing captured detrital zircons and the intrusive age of dacite porphyry, respectively. Given the intimate geological relationship between the dacite-porphyry and T2 ore, we suggest that the high-grade ores are formed after 497.82 Ma. Collectively our field observations and geochemical data reveal the detailed alteration processes that led to the development of the high-grade iron ores in the ZID, identifying distinctive features that may help to guide future exploration for additional high-grade ore deposits in the Taxkorgan region.

Textures and chemical compositions of the Narm iron oxide-apatite deposit in Kuh-e-Sarhangi District (Central Iran): Insights into the magmatic-hydrothermal mineralization

The Narm deposit is located in the Kuh-e-Sarhangi district which is a main part of the most significant Iranian iron mineralization belt, the Kashmar-Kerman Tectonic Zone (KKTZ) in Central Iran. The Narm deposit comprises an estimated total of ∼ 135000 tons of iron ore with an average grade of ∼ 55% Fe and is hosted in Early Cambrian volcano sedimentary rocks of the Rizu formation. Ore occurrences in this deposit consist of lens-shaped magnetite ore bodies, magnetite-apatite-actinolite veins and locally rare brecciated dolomite with magnetite clasts. Magnetite, pyrite, chalcopyrite and specularite associated with apatite, actinolite, biotite and carbonate minerals form the primary main mineral assemblage which is accompanied by hematite and goethite as the secondary minerals. Magnetite as the most current mineral of Narm deposit reveal the magmatic to hydrothermal evolution of mineralization. Magmatic magnetite minerals (Mag I) are dark-gray inclusion-rich magnetite spatially correlated with high temperature Ca-Fe alteration. The brighter inclusion-free hydrothermal magnetite groups (Mag II and Mag III) form during the temperature decreasing of the mineralizing fluid. According to the magnetite chemistry examination, most magnetite fall into the field for magnetite from iron-oxide apatite (IOA) deposits. Apatite minerals with F/Cl > 2, belong geochemically to the fluorapatite type. In addition to the primary dolomite, there are some hydrothermal Fe-rich dolomites and Mn bearing ones, indicating the hydrothermal fluid playing the important role for Fe-rich mineralization. In respect to fluid evolution, fluid inclusion analysis of calcite and apatite minerals form the magnetite paragenesis assemblage represent homogenization temperature range for fluid between 325 and 557℃. The salinity of fluid varied from 7.7 to 11.6 wt% NaCl equivalent and a cooling trend with the dominant chlorine complex as an agent for deposition of the Fe-rich ores. The geochemical characteristics of the δ18Ofluid values of magnetite (from + 6.1 to + 10.4‰) and δ18Ofluid values of actinolite (from + 7.7 to + 12.5‰) represent the magmatic-hydrothermal (δ18Ofluid > + 0.9 ‰) formation process. The iron rich Al-clinochlore composition from the alteration zone indicates a temperature range between 250 and 330℃ which points to a temperature reduction of hydrothermal fluids in this mineralizing zone. The integrated geochemical data from this investigation, including mineral chemistry, microthermometry of fluid inclusions and oxygen isotope data all reveal a magmatic-hydrothermal genesis for this deposit.

Employing geochemistry and geochronology to unravel genesis and tectonic setting of iron oxide-apatite deposits of the Bafq-Saghand metallogenic belt, Central Iran

The Bafq-Saghand metallogenic belt is located in the central part of the Kerman–Kashmar tectonic zone and contains 39 individual occurrences of iron oxide-apatite ± REE mineralizations. These mineral concentrations, e.g., Chadormalu, Choghart, Sechahun, and Esfordi, comprise a total of ~ 1500 million tons of iron ore with an average grade of ~ 55% Fe. In terms of origin, time, and geodynamic setting, several modes of formation have been suggested for these ore deposits, including magmatic, hydrothermal, and banded iron formation scenarios. In the present study, the tectonic setting and metallogeny of iron oxide-apatites of the Bafq-Saghand belt are investigated utilizing trace element geochemistry, age dating, and oxygen isotope analyses. The geochemical characteristics of apatite and magnetite and the δ18O values of magnetite (from − 0.1 to + 2.2 ‰) indicate a dominantly magmatic-hydrothermal (δ18O > + 0.9 ‰) formation process, although primary magmatic mineralizations were locally leached and hydrothermally redeposited (e.g., samples with δ18O < + 0.9 ‰). The Cambrian volcano-sedimentary host rocks to the mineralization is intruded by calc-alkaline tonalite, trondhjemite, granodioritic, dioritic, and granitic rocks that formed in association with subduction of the Proto-Tethys Ocean under the Gondwana supercontinent in the Neoproterozoic to Early Cambrian (525–547 Ma). Additionally, a later geodynamic episode produced intrusions of alkaline syenite and monzosyenite bodies during a continental rifting event. We provide new geochronological constraints for these younger alkaline igneous rocks that document a temporal range from 421 to 447 Ma for their intrusion. In combination with the previously reported overlapping ages of the older calc-alkaline magma bodies (525–547 Ma) with the volcano-sedimentary host rock (528 Ma) and the iron oxide mineralization (510–539 Ma), we can now exclude continental rifting as a geodynamic processes that is linked to ore formation in the region. Our results corroborate that the Bafq iron ore mineralization formed during subduction of the Proto-Tethys Ocean under the Gondwana supercontinent in a near surface continental margin setting.

Technical and Financial Assessment of Hematite (Iron Ore) Extraction from Iron Deposits of Pokhari Area, Nawalparasi

Iron and Steels is one of the top three major imports of Nepal. Based on the fact that Nepal has large amount of mineral resources, it is important to explore and exploit them rationally. This research paper is carried out to estimate the iron ore reserve of the iron ore deposits of Pokhari in Nawalparasi which was recently discovered by Department of Mines and Geology (DMG), Nepal. In this research work, the technical and financial assessment of hematite (iron ore) extraction of iron deposits of Pokhari, taking an area of one square kilo meter, has been carried out. The tonnage of iron ore and the overburden (which is quartzite and slate in this case) were estimated considering the mining process to be open cast mining using vertical cross-section method. The depth of hematite zone is taken as 100 m. The iron ore to over-burden (waste) ratio was 1:3.36. The financial analysis was done on the basis of extraction of 3600 metric tons of iron ore per day and 8,64,000 metric tons annually. The return on investment (ROI) is 34%. Thus, the research work indicates that the extraction of large amount of iron ore of Pokhari area is economical and it is a beneficial project.

Petrography and mineral chemistry of the Varena Iron Ore deposit, southeastern Lithuania: implications for the evolution of carbonate and silicate rocks and ore mineralization

The large Varena Iron Ore deposit of southeast Lithuania lies beneath 200–400 m thick sedimentary cover in the East European Craton. Several drilling projects have revealed that it contains ca. 70–200 million tons of iron ore. A metasomatic origin has been proposed by several investigators, with an igneous (mafic, ultramafic carbonatitic) origin also considered. Detailed micropetrography on a variety of ore-bearing and skarnitised samples through backscattered electron imaging, along with mineral chemical analysis and monazite dating by electron microprobe, provide support for a metasomatic origin. High-grade temperature (ca. 700–750° C) skarns containing forsterite, enstatite, spinel and diopside were formed preferentially in carbonate-rich rocks and were subsequently overprinted by amphibole-bearing (tremolite, actinolite, anthophyllite and hornblende) skarns. A low-temperature hydrous influx and changing redox conditions not only caused the serpentinization of the earlier skarns, but also deposited a considerable amount of iron ore in the form of magnetite. Iron was derived from various sources and was accompanied by sulphide, apatite, REE and other mineralizations. The ca. 1.78 Ga monazite grew during the regional metamorphism, while ca. 1.54 Ga is attributed to the last mineralization phases.

Contested Landscapes Of Displacement: Oliver Iron and Minnesota's Hibbing District

This paper explores the ways that communities, the iron industry, and the state responded to iron mining development in Minnesota's Mesabi Range. The Mesabi Range in northern Minnesota was the most productive iron range in the United States from 1895 to today, producing more than 3.8 billion tons of iron ore. The removal of all of this iron produced tremendous changes to the landscape, which communities in the Mesabi Range had to negotiate.

Materials Flows Analysis on the Beneficiation and Roasting Processes of a Typical Rare Earth Mineral

The aim of this paper is to explore material flow analysis, study the resource consumption and environmental impact of the production preparation process of typical rare earth materials. The results showed that in the beneficiation processes, producing one ton of rare earth concentrates (Rare Earth Oxide, REO50%) will also produces 27 tons of iron ore and 21 tons of tailings. The recovery of rare earths is only 16.8%. In roasting processes, roasting one ton (REO50%) of rare earth concentrates will emits 150 ~ 200Kg sulfuric acid mist, 500 ~ 600Kg sulfur dioxide, 30 ~ 40Kg fluoride, 30 ~ 50Kg smoke and1t (containing thorium) radioactive slag, and 1.2 tons of concentrated sulfuric acid should be used. The lower recoveries and large-scale of concentrated sulfuric acid used in roasting processes in rare earth industry are the main reasons lead to high pollution and high emissions.

Polysaccharide Depressants for the Reverse Flotation of Iron Ore

Review of reverse flotation of iron ore is presented with a focus on the polysaccharide depressants used and the corresponding adsorption phenomena. Iron oxide minerals have a special affinity for starch and other polysaccharides, and this special property facilitates their depression during the reverse cationic flotation of silica with ether amines in Brazil (Peres and Correa, in Miner Eng 9:12 [1]). Adsorption of polysaccharides at the hematite surface is explained by the acid/base interaction model in which hydroxyl groups at the hematite surface interact with polysaccharide molecules. Of course adsorption of modified or unmodified starch makes the surface of iron oxide minerals, such as hematite, hydrophilic. In Brazil more than 250 M tons of iron ore concentrate production per annum is achieved using polysaccharides in the reverse flotation process to remove silica gangue. For example, in 1996 40,000 metric tons of corn starch were consumed in Brazil, out of which 80 % was used for iron ore concentration. Reverse flotation technology has not been commercialized for the concentration of iron ores from India and Australia which contain aluminum gangue minerals such as kaolinite. In this regard, improved flotation chemistries need to be developed for such ores.

After the Storm: Ojibwe Treaty Rights Twenty-Five Years after the Voigt Decision

After the Storm:Ojibwe Treaty Rights Twenty-Five Years after the Voigt Decision Patty Loew (bio) and James Thannum (bio) In April 2009, when Ojibwe tribal members Neil and Chris Peterson traveled to Trout Lake to spear walleye pike in a centuries-old tribal tradition, the boat landing was quiet.1 There were no rock-throwing crowds, no gauntlets of angry demonstrators to walk, and no television reporters to dodge. No one attempted to swamp their boat. Absent were signs that read "Save a Fish, Spear an Indian." Twenty-five years ago, when Ojibwe spearfishers, like the Peterson brothers, attempted to harvest their walleyes, northern Wisconsin boat landings were battlegrounds of chaos and violence. The struggle involved the exercise of hunting, fishing, and gathering rights reserved in three mid-nineteenth-century land cession treaties the Ojibwe negotiated with the federal government. In 1974 the Ojibwe initiated a successful lawsuit against the state of Wisconsin, arguing that the state had systematically suppressed those rights throughout the twentieth century. However, when the modern Ojibwe walleye harvest began in 1985, angry mobs attempted to prevent tribal spearers from exercising their treaty rights in what one tribal member described as a "war-like, siege-like occupation."2 It became clear to the Ojibwe that opposition to their court-affirmed treaty rights was not limited to the recent actions of treaty opponents in northern Wisconsin. It was part of an ongoing nationwide struggle typified by the "fish-ins" of the 1960s, when Indian nations in the Northwest reaffirmed their treaty fishing rights along the Columbia River. As in the Northwest, antitreaty groups in Wisconsin, Michigan, and Minnesota failed to understand that when tribes ceded land and retained off-reservation harvesting rights on those lands and waters, they had established [End Page 161] contractual obligations with the United States. This failure to acknowledge that the age of a contract does not impact its validity laid the foundation for ongoing conflict throughout the Great Lakes region in the coming decades. In 1999 the struggle culminated in the US Supreme Court's affirmation of Ojibwe treaty rights in its historic Minnesota v. Mille Lacs decision, a judgment legal observers described as a clear victory for proponents of Indian sovereignty. This article examines the socioeconomic, political, and cultural factors that contributed to the spearfishing crisis twenty-five years ago and the state of relations between Native and non-Native residents in the ceded territory today. It focuses on Wisconsin, where the most virulent protests occurred. Because most residents learned about the controversy through newspaper and television news accounts, the article pays special attention to media coverage of the boat landing struggles. It argues that the relative calm that exists today is attributable to increased public awareness about treaty rights and sovereignty, largely due to education efforts and better reporting by the media. It also argues that the contributions of the Ojibwe bands themselves over the past twenty-five years to maintain and improve the natural resources within the ceded territory has also had a positive effect. Today, few would describe Wisconsin as the "Mississippi of the North," as the national media did twenty-five years ago.3 The boat landings are silent. The walleye resource has remained stable. Tourism has not collapsed, as treaty opponents had predicted, and nearly all counties within the ceded territory have seen growth rates in per capita income that far exceed that of the state as a whole.4 Concepts like "treaty rights" and "Indian sovereignty" no longer elicit feelings of panic. Although some tribal members suggest that the bigotry that fueled the violent protests twenty-five years ago still lurks under the surface, most agree that overt racism is gone. The Treaties The contemporary struggles had their roots in four treaties signed in 1836, 1837, 1842, and 1854 in which the Ojibwe ceded millions of acres in the Great Lakes region. Historian David Wrone estimated that the treaties brought to the United States about 170 billion board feet of timber, 150 billion tons of iron ore, and 15,000 lakes as well as rivers, ports, and [End Page 162] power sites.5 In exchange, the Ojibwe insisted upon the right to hunt, fish...

Implementing a Production Schedule at LKAB's Kiruna Mine

LKAB's Kiruna Mine, located in northern Sweden, produces about 24 million tons of iron ore yearly using an underground mining method known as sublevel caving. To efficiently run the mills that process the iron ore, the mine must deliver planned quantities of three ore types. We used mixed-integer programming to schedule Kiruna's operations, specifically, which production blocks to mine and when to mine them to minimize deviations from monthly planned production quantities while adhering to operational restrictions. These production schedules save costs compared to schedules produced manually by meeting desired production quantities more closely and reducing employee time spent on preparing schedules.

Implementing a Production Schedule at LKAB?s Kiruna Mine

LKAB's Kiruna Mine, located in northern Sweden, produces about 24 million tons of iron ore yearly using an underground mining method known as sublevel caving. To efficiently run the mills that proc...

A Large Scale Application of Slon Magnetic Separator in Meishan Iron Ore Mine

Meishan Iron Mine processes 4 million tons of iron ore and produces about 2.6 million tons of iron concentrate annually. Because of a relatively high content of phosphorus, the iron concentrate does not meet the market requirements. In recent years, 18 SLon‐ 1500 magnetic separators have been applied to reduce phosphorus to upgrade the concentrate quality. This paper describes research, test work and industrial application of SLon magnetic separator in the mine.

Iron Ore and Steel: A Case Study of the Economic Causes and Consequences of Vertical Integration

FUEL, water, and iron ore are the most important inputs used in the production of pig iron; pig iron is the most important input used in the production of steel. Because of the high transportation costs, before I830 American pig iron producers found it most profitable to locate where these three inputs existed in conjunction.1 At this time successful pig iron firms were small, sold their product in narrow geographical markets, and produced for their own use most of the necessary raw material inputs. After i 830, as anthracite coal became an economical fuel, as huge geographically concentrated deposits of iron ore were discovered and developed in areas far away from the nation's major population centers, and as the nation's internal transportation improved, sharply increased scale economies arose in the production of both of pig iron's principal mineral inputs. At the same time, the scale economics of pig iron production were increasing at a much slower rate. Thus, most successful pig iron producers began to realize diminishing profits in the production of both iron ore and fuel. Hence, they began to find that it was more profitable to buy both mineral inputs in the market. This realization led to a trend toward less backward integration by pig iron producers (and their successors, the crude steel producers) that continued unabated until the mid-I8gos. Between I896 and I900 more than two-thirds of the total iron ore consumed in the United States came from mines located in the Lake Superior region. In I896 more than one hundred companies were located in this region, and they produced 9,669,000 tons of iron ore. Twenty-six of these companies produced at least Ioo,ooo tons of iron ore and five produced more than 400,000 tons. The combined output of the five largest firms totalled 3,I30,000 tons and the largest (the Minnesota Iron Ore Company) produced almost goo,ooo tons. Only one of these five companies (the Oliver Iron Mining Company) was owned by a steel producer.2 The total iron ore output of the Lake Superior region soared to

Prospecção hidrobiológica da Baía de Sepetiba

Côr das águas de Sepetiba; as pròpriamente marítimas, pela Escala de Forel e as outras côres aparentes totais feitas por comparação com escalas de SÉGUY e com o Dicionário de Côres de MAERZ &amp; PAUL, 1950. Côr Forel nº6 mostrava no litoral cirrípedes como a Tetraclita squamosa, nas rochas; Águas com a cianofícea planctônica Trichodesmium erythraeum tinham côr de "fôlha de bananeira" ou alpine green. O verde esmeralda mais intenso no local 7, com plancto maciço da diatomácea Coscinodiscus; a parte central da Baía com 150 [quilometros quadrados], cheia de larvas de camarão Penaeus schmidti, águas de cõr de ferrugem nas superfícies das águas; os estuários côr caramelo, isabellinus e bistre. Êste levantamento preliminar serve para comparações futuras, pois a Baía de Sepetiba ainda não é poluída. Futuramente haverá um pôrto de minérios com 3.000.000 de toneladas anuais, cais do pôrto, siderúrgicas e outras indústrias que a poluirão. Várias cõres de águas poluídas da Baía de Guanabara, como águas negras, águas côr de asfalto e outras escurecidas não foram encontradas em Sepetiba. Também não foram encntradas "águas vermelhas" com plancto predominante de dinoflagelados do que já vimos na Baía de Guanabara seguidos de mortandadas de peixes. A fig. 3 mostra as curvas de transparência, e a relação entre côr e transparência é dada para as côres totais aparentes. Foi marcado o coeficiente de extinção da luz K, pelo cálculo a partir do Disco de Secchi. Havendo poluições todos êsses dados que apresentamos deverão ser alterados.

Productivity, Labor Demand and Cost in a Continuous Production Facility

IN Hicksian theory, the short-run demand for labor and marginal cost of a single output firm are derived from the marginal physical product curve. Marginal productivity analysis will be proved inapplicable to a steel mill department and the marginal cost and demand for labor will be derived from a local union contract, the standard crew agreement. The term 'firm' in traditional theory was clearly not meant to apply to a multi-process, multi-product steel plant. Its basic production facilities include fifty iron and steel furnaces and 500 coke ovens which must be operated continuously during the planning period. Semi-continuous, partially adaptable, processes include fifteen rolling mills and processing lines for transforming steel ingots into hundreds of different types of structural beams, plate, cold rolled and galvanized sheets and tin plate. The steel plants' raw material inputs include six million tons of iron ore, three million tons of scrap and two-thirds as much water as the city of Chicago. Overhead capital may include iOO miles of railroad tracks and 900 cars. This description should be sufficient to establish that output is the joint product of many separate production units or departments. The total and marginal products do not exist because, as Eiteman' showed, a marginal change in the output of the firm is the sum of coordinated and often non-proportional changes in the output of the departments which are the fundamental cost and production units, like the theoretical 'firm'. Departments are given current output goals every ten days which they must meet in order to synchronize their output with other departments. Overall plans are established for three months. Some firms issue labor constraints on the number of workers permitted at each level of output but state that these are seldom binding. The department is supposed to minimize cost. If it succeeds in reducing it below its historical level, management and even the workers may receive a bonus for doing so. The minimization of cost and tcchnical

SOME CHANGES IN DOMESTIC IRON MINING AS A RESULT OF PELLETIZATION1

ABSTRACT The purpose of this study is to assess the effects that pelletization has had on the iron ore production patterns in the United States between 1950 and 1965. To achieve this, the output of usable tons of iron ore, on a county basis, was mapped in order to describe and analyze the pattern of iron mining over the fifteen-year-period. It was found that pelletization engendered significant geographic and economic change in the domestic iron mining industry. The Lake Superior Region continued as the major domestic producer, followed in order by the Western Region, the Northeastern Region, the Central and Gulf Region, and the Southeastern Region. The importance of many mining districts either decreased (Southeastern Region) or increased (Western, Central, and Gulf regions) subsequent to the development of pelletization. Imports of foreign ore continued to affect some districts, but where pelletization was fully operative, imports had little effect. A major finding of the study was that in regions where...

Irrigation in the Rhodesian Lowveld

Despite the political problems of the last six years with the break up of fede? ration, the unila er declaration independence, and the application of sanctions, Rhodesia's economy has shown a remarkable resilience and has not suffered as badly as many economists had predicted. This is due in part to the country's diversified economic basis and help received from South Africa, Portugal and elsewhere. Rhodesia is comparatively well endowed with a large variety of minerals, whose export value in 1964 was nearly ?27 million, consisting of gold worth ?7-2 million, asbestos ?6*8 million, copper ?4-1 million, coal ?3-4 million, chromite ?2-2 million, tin ? -65 million, iron ore ? -58 million, and other minerals. Reserves of coal and iron ore are large with a production of over 3 million tons of coal and a million tons of iron ore in 1964. Hydroelectricity generated from Kariba will be able to supply all of Rhodesia's power needs for years to come. Industrial development has been rapid since 1938 when net output was worth ?2*3 million, compared to a net output worth ?22 million in 1963, while numbers employed have also increased from 17,500 to 82,400 during the period 1938-63. Manufacturing is now the largest single sector in the Rhodesian economy with 18 per cent of the gross domestic product, compared to commercial agriculture with 15 per cent of the G.D.P. However, commercial agriculture was the largest employer of African labour with 44 per cent of a total African labour force of 622,000. Rhodesian agriculture is divided into two distinct sectors, the cash and the subsis? tence sectors. The commercial sector is market-orientated and consists largely of Euro? pean farmers operating on a large scale, while the subsistence sector consists almost entirely of African peasant cultivators operating on a small scale and with little (market emphasis. Over 90 per cent of the African working population are engaged in farm? ing, and there are nearly half a million African subsistence farmers compared to only 6200 farms in the commercial sector, most of them owned by Europeans, but includ? ing an increasing number of Africans. Agriculture is, therefore, of paramount importance to the Rhodesian economy and will continue to play a major role for many years to come. However, despite the apparent vigour of the economy there are some disquieting features. The contribution of subsistence agriculture to the national economy is small as yet, with only 67 per cent of the G.D.P. in 1964, and most African farmers are inefficient with a low standard of living. Determined efforts are being made by the Rhodesian government to improve agricultural productivity by such means as cooperative marketing schemes, the African Master Farmers' Scheme, soil conservation programme, pasture management, the upgrading of cattle and the introduction of new and better varieties of crops. The African population is expanding at a rate of 3 xz per cent per annum, having in? creased from about half a million in 1901 to 3 lz million in 1961. Increasing numbers of Africans are migrating to Bulawayo and Salisbury, and the latter city, which had only 33,000 people in 1933, increased rapidly to over 300,000 by 1966. A major reason for this urban drift is the effect of the widening gap between urban and rural earnings. According to Professor Arthur Lewis another important reason is the in? fluence of accelerated schooling causing African primary school leavers to flock to the towns to seek work, as suitable employment is not available in the country (Lewis,

ON SOME ACHIEVEMENTS OF GEOLOGICAL SURVEYING AND PROSPECTING IN THE CHINESE PEOPLE'S REPUBLIC

Oil and gas prospecting in China has located promising shows in Tertiary deposits of the Ts'aidam valley of southern China, the Kansu corridor, the Chungar trough of northwest China, and in Mesozoic deposits of the Turf ang valley in Sikang. The iron content of Precambrian quartzite ores in northern China averages 47 percent in 1957, 19 million tons of iron ore were mined in China. Reports on recent product and prospects for future development are included for manganese, tin, tungsten, copper, bauxite, mercury, antimony, molybdenum, nickel, cobalt, chromites, titanium, vanadium, gold, rare earths, uranium, boron, phosphorites, apatites, quartz, diamond, and asbestos P. Ya. Antropov M. Russell

Entering the first year of the seven-year plan

Entering the first year of the seven-year plan

Iron Ores from Overseas

AS DOMESTIC SUPPLIES of iron ore suitable for feeding directly to furnaces dwindled, it was quite natural for U. S. makers of steel to turn to Canada for sources that could augment domestic deposits. But our foreign explorations did not stop with Canada. We also looked farther afield and today are importing a somewhat larger volume of ores from countries overseas than from our neighbor to the north. Ten years ago these imports amounted to only 1,650,000 tons, which came primarily from Chile. Last year the United States imported approximately 17 million gross tons of iron ore, exclusive of Canadian sources. This is a ten-fold increase in a single decade. Over half of the 1956 tonnage from overseas came from Venezuela, with lesser tonnages from Peru, Chile, Brazil, Liberia, Sweden and other countries. With the exception of Sweden, the major growth in iron ore production in these foreign countries has been brought about through United States private technical aid and capital investment. In the years ahead we can look for further increases in our volume of overseas imports. While our relative reliance on other countries will probably not increase as rapidly as our ore dependence upon Canada, American companies are continuing to explore for good, workable deposits in a number of foreign lands. Many considerations had to be weighed when a choice presented itself between beneficiation of low grade domestic ore, or going to Canada, or moving farther afield. Let us consider briefly the factors that normally influence a decision to undertake mining in a distant land. Being a geologist, I place the quantity and quality of ore, either proved or potential, at the top of the list. More often than not it is an undeveloped or partially developed prospect that is being weighed. Granted that the geology is favorable, risk money must be spent to determine whether the prospect can be proved up to become a mine. But even before proving up a deposit, there are pertinent matters to be weighed. An ore body may look huge and it may be rich, but if other features stand in the way of profitable operation, there is no benefit in drilling or tunneling or sinking test shafts to establish a firm ore reserve. Transportation facilities needed to move large tonnages of the ore to our shores are of prime importance. Here at home, when a ton of Mesabi ore reaches a furnace at Youngstown, Ohio, the rail and lake movement and the handling between the mine and furnace make up 43 percent of the delivered cost. Where vastly greater distances are involved, shipping costs are an even greater part of the total. If transportation were less of a problem, we would doubtless be using far more of the high grade Brazilian ore in the United States today. At the foreign sources developed by American steel and mining companies in recent years, there has been a great contrast in the new installations needed to get the ore aboard ocean carriers. At the port of Monrovia, Liberia Mining Company had only to install stockpiling and loading equipment. At San Juan harbor in Peru, Marcona Mining Company found a good natural harbor and had no great difficulty constructing a dock with conveyors to load the ships. At the other extreme, Orinoco Mining Company dredged many miles of channel in the Venezuelan River and had to install a huge floating dock to compensate for the seasonal rise and fall of more than forty feet in the river's level. One hundred and twenty miles of new rail lines span the gap between this dock and the mine at Cerro Bolivar. Marcona moves its ore from mine to port in 50-ton trailer trucks over 17 miles of asphalt-paved road. The Liberian development and Bethlehem's mine in Venezuela each called for railroads about 40 miles in length. These examples illustrate the variety of transportation problems that occur in foreign ore developments. No two are alike; and whenever an American consumer or miner looks at a foreign deposit, a sound plan for getting the ore here and corresponding cost estimates must be developed.